Migrate to AssertJ in Kotlin tests

Closes gh-23475

spring-beans/src/test/kotlin/org/springframework/beans/KotlinBeanUtilsTests.kt

@@ -16,7 +16,7 @@
 
 package org.springframework.beans
 
-import org.junit.jupiter.api.Assertions.*
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 
 /**
@@ -31,47 +31,47 @@ class KotlinBeanUtilsTests {
 	fun `Instantiate immutable class`() {
 		val constructor = BeanUtils.findPrimaryConstructor(Foo::class.java)!!
 		val foo = BeanUtils.instantiateClass(constructor, "a", 3)
-		assertEquals("a", foo.param1)
-		assertEquals(3, foo.param2)
+		assertThat(foo.param1).isEqualTo("a")
+		assertThat(foo.param2).isEqualTo(3)
 	}
 
 	@Test
 	fun `Instantiate immutable class with optional parameter and all parameters specified`() {
 		val constructor = BeanUtils.findPrimaryConstructor(Bar::class.java)!!
 		val bar = BeanUtils.instantiateClass(constructor, "a", 8)
-		assertEquals("a", bar.param1)
-		assertEquals(8, bar.param2)
+		assertThat(bar.param1).isEqualTo("a")
+		assertThat(bar.param2).isEqualTo(8)
 	}
 
 	@Test
 	fun `Instantiate immutable class with optional parameter and only mandatory parameters specified by position`() {
 		val constructor = BeanUtils.findPrimaryConstructor(Bar::class.java)!!
 		val bar = BeanUtils.instantiateClass(constructor, "a")
-		assertEquals("a", bar.param1)
-		assertEquals(12, bar.param2)
+		assertThat(bar.param1).isEqualTo("a")
+		assertThat(bar.param2).isEqualTo(12)
 	}
 
 	@Test
 	fun `Instantiate immutable class with optional parameter specified with null value`() {
 		val constructor = BeanUtils.findPrimaryConstructor(Bar::class.java)!!
 		val bar = BeanUtils.instantiateClass(constructor, "a", null)
-		assertEquals("a", bar.param1)
-		assertEquals(12, bar.param2)
+		assertThat(bar.param1).isEqualTo("a")
+		assertThat(bar.param2).isEqualTo(12)
 	}
 
 	@Test  // gh-22531
 	fun `Instantiate immutable class with nullable parameter`() {
 		val constructor = BeanUtils.findPrimaryConstructor(Qux::class.java)!!
 		val bar = BeanUtils.instantiateClass(constructor, "a", null)
-		assertEquals("a", bar.param1)
-		assertNull(bar.param2)
+		assertThat(bar.param1).isEqualTo("a")
+		assertThat(bar.param2).isNull()
 	}
 
 	@Test  // SPR-15851
 	fun `Instantiate mutable class with declared constructor and default values for all parameters`() {
 		val baz = BeanUtils.instantiateClass(Baz::class.java.getDeclaredConstructor())
-		assertEquals("a", baz.param1)
-		assertEquals(12, baz.param2)
+		assertThat(baz.param1).isEqualTo("a")
+		assertThat(baz.param2).isEqualTo(12)
 	}
 
 	class Foo(val param1: String, val param2: Int)

spring-beans/src/test/kotlin/org/springframework/beans/factory/annotation/KotlinAutowiredTests.kt

@@ -16,16 +16,14 @@
 
 package org.springframework.beans.factory.annotation
 
+import org.assertj.core.api.Assertions.assertThat
+import org.assertj.core.api.Assertions.assertThatExceptionOfType
 import org.junit.jupiter.api.Test
-
+import org.springframework.beans.factory.BeanCreationException
 import org.springframework.beans.factory.support.DefaultListableBeanFactory
 import org.springframework.beans.factory.support.RootBeanDefinition
-import org.springframework.tests.sample.beans.TestBean
-
-import org.junit.jupiter.api.Assertions.*
-import org.junit.jupiter.api.fail
-import org.springframework.beans.factory.BeanCreationException
 import org.springframework.tests.sample.beans.Colour
+import org.springframework.tests.sample.beans.TestBean
 
 /**
  * Tests for Kotlin support with [Autowired].
@@ -48,9 +46,9 @@ class KotlinAutowiredTests {
 		bf.registerSingleton("testBean", tb)
 
 		val kb = bf.getBean("annotatedBean", KotlinBean::class.java)
-		assertSame(tb, kb.injectedFromConstructor)
-		assertSame(tb, kb.injectedFromMethod)
-		assertSame(tb, kb.injectedField)
+		assertThat(kb.injectedFromConstructor).isSameAs(tb)
+		assertThat(kb.injectedFromMethod).isSameAs(tb)
+		assertThat(kb.injectedField).isSameAs(tb)
 	}
 
 	@Test
@@ -64,9 +62,9 @@ class KotlinAutowiredTests {
 		bf.registerBeanDefinition("annotatedBean", bd)
 
 		val kb = bf.getBean("annotatedBean", KotlinBean::class.java)
-		assertNull(kb.injectedFromConstructor)
-		assertNull(kb.injectedFromMethod)
-		assertNull(kb.injectedField)
+		assertThat(kb.injectedFromConstructor).isNull()
+		assertThat(kb.injectedFromMethod).isNull()
+		assertThat(kb.injectedField).isNull()
 	}
 	
 	@Test  // SPR-15847
@@ -82,9 +80,9 @@ class KotlinAutowiredTests {
 		bf.registerSingleton("testBean", tb)
 
 		val kb = bf.getBean("bean", KotlinBeanWithMandatoryAndOptionalParameters::class.java)
-		assertSame(tb, kb.injectedFromConstructor)
-		assertEquals("foo", kb.optional)
-		assertEquals("bar", kb.initializedField)
+		assertThat(kb.injectedFromConstructor).isSameAs(tb)
+		assertThat(kb.optional).isEqualTo("foo")
+		assertThat(kb.initializedField).isEqualTo("bar")
 	}
 
 	@Test
@@ -98,9 +96,9 @@ class KotlinAutowiredTests {
 		bf.registerBeanDefinition("bean", bd)
 
 		val kb = bf.getBean("bean", KotlinBeanWithOptionalParameters::class.java)
-		assertNotNull(kb.optional1)
-		assertEquals("foo", kb.optional2)
-		assertEquals("bar", kb.initializedField)
+		assertThat(kb.optional1).isNotNull()
+		assertThat(kb.optional2).isEqualTo("foo")
+		assertThat(kb.initializedField).isEqualTo("bar")
 	}
 
 	@Test  // SPR-15847
@@ -116,8 +114,8 @@ class KotlinAutowiredTests {
 		bf.registerSingleton("testBean", tb)
 
 		val kb = bf.getBean("bean", KotlinBeanWithOptionalParameterAndExplicitConstructor::class.java)
-		assertSame(tb, kb.injectedFromConstructor)
-		assertEquals("foo", kb.optional)
+		assertThat(kb.injectedFromConstructor).isSameAs(tb)
+		assertThat(kb.optional).isEqualTo("foo")
 	}
 
 	@Test  // SPR-15847
@@ -135,9 +133,9 @@ class KotlinAutowiredTests {
 		bf.registerSingleton("colour", colour)
 
 		val kb = bf.getBean("bean", KotlinBeanWithAutowiredSecondaryConstructor::class.java)
-		assertSame(tb, kb.injectedFromConstructor)
-		assertEquals("bar", kb.optional)
-		assertSame(colour, kb.injectedFromSecondaryConstructor)
+		assertThat(kb.injectedFromConstructor).isSameAs(tb)
+		assertThat(kb.optional).isEqualTo("bar")
+		assertThat(kb.injectedFromSecondaryConstructor).isSameAs(colour)
 	}
 
 	@Test  // SPR-16012
@@ -151,7 +149,7 @@ class KotlinAutowiredTests {
 		bf.registerBeanDefinition("bean", bd)
 
 		val kb = bf.getBean("bean", KotlinBeanWithPrimaryAndDefaultConstructors::class.java)
-		assertNotNull(kb.testBean)
+		assertThat(kb.testBean).isNotNull()
 	}
 
 	@Test  // SPR-16012
@@ -167,7 +165,7 @@ class KotlinAutowiredTests {
 		bf.registerSingleton("testBean", tb)
 
 		val kb = bf.getBean("bean", KotlinBeanWithPrimaryAndDefaultConstructors::class.java)
-		assertEquals(tb, kb.testBean)
+		assertThat(kb.testBean).isEqualTo(tb)
 	}
 
 	@Test  // SPR-16289
@@ -197,13 +195,9 @@ class KotlinAutowiredTests {
 		bf.registerSingleton("testBean", tb)
 		val colour = Colour.BLUE
 		bf.registerSingleton("colour", colour)
-		
-		try {
+
+		assertThatExceptionOfType(BeanCreationException::class.java).isThrownBy {
 			bf.getBean("bean", KotlinBeanWithSecondaryConstructor::class.java)
-			fail("should have thrown a BeanCreationException")			
-		}
-		catch (e: BeanCreationException) {
-			// expected
 		}
 	}
 

spring-context/src/test/kotlin/org/springframework/context/annotation/AnnotationConfigApplicationContextExtensionsTests.kt

@@ -16,7 +16,7 @@
 
 package org.springframework.context.annotation
 
-import org.junit.jupiter.api.Assertions.assertNotNull
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.beans.factory.getBean
 import org.springframework.context.support.registerBean
@@ -34,9 +34,9 @@ class AnnotationConfigApplicationContextExtensionsTests {
 		val applicationContext = AnnotationConfigApplicationContext {
 			registerBean<Foo>()
 		}
+		assertThat(applicationContext).isNotNull()
 		applicationContext.refresh()
-		assertNotNull(applicationContext)
-		assertNotNull(applicationContext.getBean<Foo>())
+		applicationContext.getBean<Foo>()
 	}
 
 	class Foo

spring-context/src/test/kotlin/org/springframework/context/annotation/KotlinConfigurationClassTests.kt

@@ -16,8 +16,9 @@
 
 package org.springframework.context.annotation
 
-import org.junit.jupiter.api.Assertions.*
-import org.junit.jupiter.api.fail
+
+import org.assertj.core.api.Assertions.assertThat
+import org.assertj.core.api.Assertions.assertThatExceptionOfType
 import org.junit.jupiter.api.Test
 import org.springframework.beans.factory.getBean
 import org.springframework.beans.factory.parsing.BeanDefinitionParsingException
@@ -26,12 +27,8 @@ class KotlinConfigurationClassTests {
 
 	@Test
 	fun `Final configuration with default proxyBeanMethods value`() {
-		try {
+		assertThatExceptionOfType(BeanDefinitionParsingException::class.java).isThrownBy {
 			AnnotationConfigApplicationContext(FinalConfigurationWithProxy::class.java)
-			fail("should have thrown a BeanDefinitionParsingException")			
-		}
-		catch (e: BeanDefinitionParsingException) {
-			// expected
 		}
 	}
 
@@ -39,7 +36,7 @@ class KotlinConfigurationClassTests {
 	fun `Final configuration with proxyBeanMethods set to false`() {
 		val context = AnnotationConfigApplicationContext(FinalConfigurationWithoutProxy::class.java)
 		val foo = context.getBean<Foo>()
-		assertEquals(foo, context.getBean<Bar>().foo)
+		assertThat(context.getBean<Bar>().foo).isEqualTo(foo)
 	}
 
 

spring-context/src/test/kotlin/org/springframework/context/annotation/Spr16022Tests.kt

@@ -16,7 +16,7 @@
 
 package org.springframework.context.annotation
 
-import org.junit.jupiter.api.Assertions.assertEquals
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.beans.factory.BeanFactory
 import org.springframework.beans.factory.getBean
@@ -39,11 +39,11 @@ class Spr16022Tests {
 
 	private fun assert(context: BeanFactory) {
 		val bean1 = context.getBean<MultipleConstructorsTestBean>("bean1")
-		assertEquals(0, bean1.foo)
+		assertThat(bean1.foo).isEqualTo(0)
 		val bean2 = context.getBean<MultipleConstructorsTestBean>("bean2")
-		assertEquals(1, bean2.foo)
+		assertThat(bean2.foo).isEqualTo(1)
 		val bean3 = context.getBean<MultipleConstructorsTestBean>("bean3")
-		assertEquals(3, bean3.foo)
+		assertThat(bean3.foo).isEqualTo(3)
 
 	}
 

spring-context/src/test/kotlin/org/springframework/context/support/BeanDefinitionDslTests.kt

@@ -16,9 +16,8 @@
 
 package org.springframework.context.support
 
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertNotNull
-import org.junit.jupiter.api.Assertions.assertTrue
+import org.assertj.core.api.Assertions.assertThat
+import org.assertj.core.api.Assertions.assertThatExceptionOfType
 import org.junit.jupiter.api.fail
 import org.junit.jupiter.api.Test
 import org.springframework.beans.factory.NoSuchBeanDefinitionException
@@ -45,10 +44,10 @@ class BeanDefinitionDslTests {
 			refresh()
 		}
 		
-		assertNotNull(context.getBean<Foo>())
-		assertNotNull(context.getBean<Bar>("bar"))
-		assertTrue(context.isPrototype("bar"))
-		assertNotNull(context.getBean<Baz>())
+		context.getBean<Foo>()
+		context.getBean<Bar>("bar")
+		assertThat(context.isPrototype("bar")).isTrue()
+		context.getBean<Baz>()
 	}
 
 	@Test
@@ -72,13 +71,9 @@ class BeanDefinitionDslTests {
 			refresh()
 		}
 
-		assertNotNull(context.getBean<Foo>())
-		assertNotNull(context.getBean<Bar>("bar"))
-		try { 
-			context.getBean<Baz>()
-			fail("Expect NoSuchBeanDefinitionException to be thrown")
-		}
-		catch(ex: NoSuchBeanDefinitionException) { null }
+		context.getBean<Foo>()
+		context.getBean<Bar>("bar")
+		assertThatExceptionOfType(NoSuchBeanDefinitionException::class.java).isThrownBy { context.getBean<Baz>() }
 	}
 
 	@Test
@@ -100,14 +95,10 @@ class BeanDefinitionDslTests {
 			refresh()
 		}
 
-		assertNotNull(context.getBean<Foo>())
-		assertNotNull(context.getBean<Bar>("bar"))
-		assertEquals("foofoo", context.getBean<FooFoo>().name)
-		try {
-			context.getBean<Baz>()
-			fail("Expect NoSuchBeanDefinitionException to be thrown")
-		}
-		catch(ex: NoSuchBeanDefinitionException) { null }
+		context.getBean<Foo>()
+		context.getBean<Bar>("bar")
+		assertThat(context.getBean<FooFoo>().name).isEqualTo("foofoo")
+		assertThatExceptionOfType(NoSuchBeanDefinitionException::class.java).isThrownBy { context.getBean<Baz>() }
 	}
 
 	@Test  // SPR-16412
@@ -126,7 +117,7 @@ class BeanDefinitionDslTests {
 		}
 
 		for (i in 1..5) {
-			assertNotNull(context.getBean("string$i"))
+			context.getBean("string$i")
 		}
 	}
 
@@ -144,7 +135,7 @@ class BeanDefinitionDslTests {
 		}
 
 		val barbar = context.getBean<BarBar>()
-		assertEquals(2, barbar.foos.size)
+		assertThat(barbar.foos.size).isEqualTo(2)
 	}
 
 	@Test  // SPR-17292

spring-context/src/test/kotlin/org/springframework/context/support/GenericApplicationContextExtensionsTests.kt

@@ -16,7 +16,6 @@
 
 package org.springframework.context.support
 
-import org.junit.jupiter.api.Assertions.assertNotNull
 import org.junit.jupiter.api.Test
 import org.springframework.beans.factory.getBean
 
@@ -32,7 +31,7 @@ class GenericApplicationContextExtensionsTests {
 		val context = GenericApplicationContext()
 		context.registerBean<BeanA>()
 		context.refresh()
-		assertNotNull(context.getBean<BeanA>())
+		context.getBean<BeanA>()
 	}
 
 	@Test
@@ -40,7 +39,7 @@ class GenericApplicationContextExtensionsTests {
 		val context = GenericApplicationContext()
 		context.registerBean<BeanA>("a")
 		context.refresh()
-		assertNotNull(context.getBean("a"))
+		context.getBean("a")
 	}
 
 	@Test
@@ -48,7 +47,7 @@ class GenericApplicationContextExtensionsTests {
 		val context = GenericApplicationContext()
 		context.registerBean { BeanA() }
 		context.refresh()
-		assertNotNull(context.getBean<BeanA>())
+		context.getBean<BeanA>()
 	}
 
 	@Test
@@ -56,7 +55,7 @@ class GenericApplicationContextExtensionsTests {
 		val context = GenericApplicationContext()
 		context.registerBean("a") { BeanA() }
 		context.refresh()
-		assertNotNull(context.getBean("a"))
+		context.getBean("a")
 	}
 
 	@Test
@@ -65,8 +64,8 @@ class GenericApplicationContextExtensionsTests {
 		context.registerBean<BeanA>()
 		context.registerBean { BeanB(it.getBean<BeanA>()) }
 		context.refresh()
-		assertNotNull(context.getBean<BeanA>())
-		assertNotNull(context.getBean<BeanB>())
+		context.getBean<BeanA>()
+		context.getBean<BeanB>()
 	}
 
 	@Test
@@ -75,8 +74,8 @@ class GenericApplicationContextExtensionsTests {
 		context.registerBean<BeanA>("a")
 		context.registerBean("b") { BeanB(it.getBean<BeanA>()) }
 		context.refresh()
-		assertNotNull(context.getBean("a"))
-		assertNotNull(context.getBean("b"))
+		context.getBean("a")
+		context.getBean("b")
 	}
 
 	class BeanA

spring-context/src/test/kotlin/org/springframework/ui/ModelExtensionsTests.kt

@@ -16,8 +16,7 @@
 
 package org.springframework.ui
 
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertTrue
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 
 /**
@@ -31,7 +30,7 @@ class ModelExtensionsTests {
 	fun setAttribute() {
 		val model:Model = ConcurrentModel()
 		model["foo"] = "bing"
-		assertTrue(model.containsAttribute("foo"))
-		assertEquals("bing", model.asMap()["foo"])
+		assertThat(model.containsAttribute("foo")).isTrue()
+		assertThat(model.asMap()["foo"]).isEqualTo("bing")
 	}
 }

spring-context/src/test/kotlin/org/springframework/ui/ModelMapExtensionsTests.kt

@@ -16,8 +16,7 @@
 
 package org.springframework.ui
 
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertTrue
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 
 /**
@@ -31,8 +30,8 @@ class ModelMapExtensionsTests {
 	fun setAttribute() {
 		val model = ModelMap()
 		model["foo"] = "bing"
-		assertTrue(model.containsAttribute("foo"))
-		assertEquals("bing", model["foo"])
+		assertThat(model.containsAttribute("foo"))
+		assertThat(model["foo"]).isEqualTo("bing")
 	}
 
 }

spring-core/src/test/kotlin/org/springframework/core/KotlinDefaultParameterNameDiscovererTests.kt

@@ -16,7 +16,7 @@
 
 package org.springframework.core
 
-import org.junit.jupiter.api.Assertions.assertEquals
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 
 class KotlinDefaultParameterNameDiscovererTests {
@@ -31,6 +31,6 @@ class KotlinDefaultParameterNameDiscovererTests {
 	fun getParameterNamesOnEnum() {
 		val constructor = MyEnum::class.java.declaredConstructors[0]
 		val actualParams = parameterNameDiscoverer.getParameterNames(constructor)
-		assertEquals(2, actualParams!!.size)
+		assertThat(actualParams!!.size).isEqualTo(2)
 	}
 }

spring-core/src/test/kotlin/org/springframework/core/KotlinGenericTypeResolverTests.kt

@@ -16,7 +16,7 @@
 
 package org.springframework.core
 
-import org.junit.jupiter.api.Assertions.assertEquals
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.core.GenericTypeResolver.resolveReturnTypeArgument
 import java.lang.reflect.Method
@@ -31,14 +31,14 @@ class KotlinGenericTypeResolverTests {
 
 	@Test
 	fun methodReturnTypes() {
-		assertEquals(Integer::class.java, resolveReturnTypeArgument(findMethod(MyTypeWithMethods::class.java, "integer")!!,
-				MyInterfaceType::class.java))
-		assertEquals(String::class.java, resolveReturnTypeArgument(findMethod(MyTypeWithMethods::class.java, "string")!!,
-				MyInterfaceType::class.java))
-		assertEquals(null, resolveReturnTypeArgument(findMethod(MyTypeWithMethods::class.java, "raw")!!,
-				MyInterfaceType::class.java))
-		assertEquals(null, resolveReturnTypeArgument(findMethod(MyTypeWithMethods::class.java, "object")!!,
-				MyInterfaceType::class.java))
+		assertThat(resolveReturnTypeArgument(findMethod(MyTypeWithMethods::class.java, "integer")!!,
+				MyInterfaceType::class.java)).isEqualTo(Integer::class.java)
+		assertThat(resolveReturnTypeArgument(findMethod(MyTypeWithMethods::class.java, "string")!!,
+				MyInterfaceType::class.java)).isEqualTo(String::class.java)
+		assertThat(resolveReturnTypeArgument(findMethod(MyTypeWithMethods::class.java, "raw")!!,
+				MyInterfaceType::class.java)).isNull()
+		assertThat(resolveReturnTypeArgument(findMethod(MyTypeWithMethods::class.java, "object")!!,
+				MyInterfaceType::class.java)).isNull()
 	}
 
 	private fun findMethod(clazz: Class<*>, name: String): Method? =

spring-core/src/test/kotlin/org/springframework/core/KotlinMethodParameterTests.kt

@@ -16,9 +16,7 @@
 
 package org.springframework.core
 
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertFalse
-import org.junit.jupiter.api.Assertions.assertTrue
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import java.lang.reflect.Method
 import java.lang.reflect.TypeVariable
@@ -49,59 +47,58 @@ class KotlinMethodParameterTests {
 
 	@Test
 	fun `Method parameter nullability`() {
-		assertTrue(MethodParameter(nullableMethod, 0).isOptional)
-		assertFalse(MethodParameter(nonNullableMethod, 0).isOptional)
+		assertThat(MethodParameter(nullableMethod, 0).isOptional).isTrue()
+		assertThat(MethodParameter(nonNullableMethod, 0).isOptional).isFalse()
 	}
 
 	@Test
 	fun `Method return type nullability`() {
-		assertTrue(MethodParameter(nullableMethod, -1).isOptional)
-		assertFalse(MethodParameter(nonNullableMethod, -1).isOptional)
+		assertThat(MethodParameter(nullableMethod, -1).isOptional).isTrue()
+		assertThat(MethodParameter(nonNullableMethod, -1).isOptional).isFalse()
 	}
 
 	@Test  // SPR-17222
 	fun `Inner class constructor`() {
-		assertFalse(MethodParameter(innerClassConstructor, 0).isOptional)
-
-		assertFalse(MethodParameter(innerClassWithParametersConstructor, 0).isOptional)
-		assertFalse(MethodParameter(innerClassWithParametersConstructor, 1).isOptional)
-		assertTrue(MethodParameter(innerClassWithParametersConstructor, 2).isOptional)
+		assertThat(MethodParameter(innerClassConstructor, 0).isOptional).isFalse()
+		assertThat(MethodParameter(innerClassWithParametersConstructor, 0).isOptional).isFalse()
+		assertThat(MethodParameter(innerClassWithParametersConstructor, 1).isOptional).isFalse()
+		assertThat(MethodParameter(innerClassWithParametersConstructor, 2).isOptional).isTrue()
 	}
 
 	@Test
 	fun `Regular class constructor`() {
-		assertFalse(MethodParameter(regularClassConstructor, 0).isOptional)
-		assertTrue(MethodParameter(regularClassConstructor, 1).isOptional)
+		assertThat(MethodParameter(regularClassConstructor, 0).isOptional).isFalse()
+		assertThat(MethodParameter(regularClassConstructor, 1).isOptional).isTrue()
 	}
 
 	@Test
 	fun `Suspending function return type`() {
-		assertEquals(Number::class.java, returnParameterType("suspendFun"))
-		assertEquals(Number::class.java, returnGenericParameterType("suspendFun"))
+		assertThat(returnParameterType("suspendFun")).isEqualTo(Number::class.java)
+		assertThat(returnGenericParameterType("suspendFun")).isEqualTo(Number::class.java)
 
-		assertEquals(Producer::class.java, returnParameterType("suspendFun2"))
-		assertEquals("org.springframework.core.Producer<? extends java.lang.Number>", returnGenericParameterTypeName("suspendFun2"))
+		assertThat(returnParameterType("suspendFun2")).isEqualTo(Producer::class.java)
+		assertThat(returnGenericParameterTypeName("suspendFun2")).isEqualTo("org.springframework.core.Producer<? extends java.lang.Number>")
 
-		assertEquals(Wrapper::class.java, returnParameterType("suspendFun3"))
-		assertEquals("org.springframework.core.Wrapper<java.lang.Number>", returnGenericParameterTypeName("suspendFun3"))
+		assertThat(returnParameterType("suspendFun3")).isEqualTo(Wrapper::class.java)
+		assertThat(returnGenericParameterTypeName("suspendFun3")).isEqualTo("org.springframework.core.Wrapper<java.lang.Number>")
 
-		assertEquals(Consumer::class.java, returnParameterType("suspendFun4"))
-		assertEquals("org.springframework.core.Consumer<? super java.lang.Number>", returnGenericParameterTypeName("suspendFun4"))
+		assertThat(returnParameterType("suspendFun4")).isEqualTo(Consumer::class.java)
+		assertThat(returnGenericParameterTypeName("suspendFun4")).isEqualTo("org.springframework.core.Consumer<? super java.lang.Number>")
 
-		assertEquals(Producer::class.java, returnParameterType("suspendFun5"))
-		assertTrue(returnGenericParameterType("suspendFun5") is TypeVariable<*>)
-		assertEquals("org.springframework.core.Producer<? extends java.lang.Number>", returnGenericParameterTypeBoundName("suspendFun5"))
+		assertThat(returnParameterType("suspendFun5")).isEqualTo(Producer::class.java)
+		assertThat(returnGenericParameterType("suspendFun5")).isInstanceOf(TypeVariable::class.java)
+		assertThat(returnGenericParameterTypeBoundName("suspendFun5")).isEqualTo("org.springframework.core.Producer<? extends java.lang.Number>")
 
-		assertEquals(Wrapper::class.java, returnParameterType("suspendFun6"))
-		assertTrue(returnGenericParameterType("suspendFun6") is TypeVariable<*>)
-		assertEquals("org.springframework.core.Wrapper<java.lang.Number>", returnGenericParameterTypeBoundName("suspendFun6"))
+		assertThat(returnParameterType("suspendFun6")).isEqualTo(Wrapper::class.java)
+		assertThat(returnGenericParameterType("suspendFun6")).isInstanceOf(TypeVariable::class.java)
+		assertThat(returnGenericParameterTypeBoundName("suspendFun6")).isEqualTo("org.springframework.core.Wrapper<java.lang.Number>")
 
-		assertEquals(Consumer::class.java, returnParameterType("suspendFun7"))
-		assertTrue(returnGenericParameterType("suspendFun7") is TypeVariable<*>)
-		assertEquals("org.springframework.core.Consumer<? super java.lang.Number>", returnGenericParameterTypeBoundName("suspendFun7"))
+		assertThat(returnParameterType("suspendFun7")).isEqualTo(Consumer::class.java)
+		assertThat(returnGenericParameterType("suspendFun7")).isInstanceOf(TypeVariable::class.java)
+		assertThat(returnGenericParameterTypeBoundName("suspendFun7")).isEqualTo("org.springframework.core.Consumer<? super java.lang.Number>")
 
-		assertEquals(Object::class.java, returnParameterType("suspendFun8"))
-		assertEquals(Object::class.java, returnGenericParameterType("suspendFun8"))
+		assertThat(returnParameterType("suspendFun8")).isEqualTo(Object::class.java)
+		assertThat(returnGenericParameterType("suspendFun8")).isEqualTo(Object::class.java)
 	}
 
 	private fun returnParameterType(funName: String) = returnMethodParameter(funName).parameterType

spring-core/src/test/kotlin/org/springframework/core/KotlinReactiveAdapterRegistryTests.kt

@@ -17,16 +17,13 @@
 package org.springframework.core
 
 import kotlinx.coroutines.Deferred
-import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.async
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.flow.toList
 import kotlinx.coroutines.runBlocking
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertTrue
-import org.junit.jupiter.api.Assertions.fail
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.reactivestreams.Publisher
 import reactor.core.publisher.Flux
@@ -35,7 +32,6 @@ import reactor.test.StepVerifier
 import java.time.Duration
 import kotlin.reflect.KClass
 
-@ExperimentalCoroutinesApi
 class KotlinReactiveAdapterRegistryTests {
 
 	private val registry = ReactiveAdapterRegistry.getSharedInstance()
@@ -44,16 +40,16 @@ class KotlinReactiveAdapterRegistryTests {
 	fun deferredToPublisher() {
 		val source = GlobalScope.async { 1 }
 		val target: Publisher<Int> = getAdapter(Deferred::class).toPublisher(source)
-		assertTrue(target is Mono<*>, "Expected Mono Publisher: " + target.javaClass.name)
-		assertEquals(1, (target as Mono<Int>).block(Duration.ofMillis(1000)))
+		assertThat(target).isInstanceOf(Mono::class.java)
+		assertThat((target as Mono<Int>).block(Duration.ofMillis(1000))).isEqualTo(1)
 	}
 
 	@Test
 	fun publisherToDeferred() {
 		val source = Mono.just(1)
 		val target = getAdapter(Deferred::class).fromPublisher(source)
-		assertTrue(target is Deferred<*>)
-		assertEquals(1, runBlocking { (target as Deferred<*>).await() })
+		assertThat(target).isInstanceOf(Deferred::class.java)
+		assertThat(runBlocking { (target as Deferred<*>).await() }).isEqualTo(1)
 	}
 
 	@Test
@@ -64,7 +60,7 @@ class KotlinReactiveAdapterRegistryTests {
 			emit(3)
 		}
 		val target: Publisher<Int> = getAdapter(Flow::class).toPublisher(source)
-		assertTrue(target is Flux<*>, "Expected Flux Publisher: " + target.javaClass.name)
+		assertThat(target).isInstanceOf(Flux::class.java)
 		StepVerifier.create(target)
 				.expectNext(1)
 				.expectNext(2)
@@ -76,12 +72,8 @@ class KotlinReactiveAdapterRegistryTests {
 	fun publisherToFlow() {
 		val source = Flux.just(1, 2, 3)
 		val target = getAdapter(Flow::class).fromPublisher(source)
-		if (target is Flow<*>) {
-			assertEquals(listOf(1, 2, 3),  runBlocking { target.toList() })
-		}
-		else {
-			fail()
-		}
+		assertThat(target).isInstanceOf(Flow::class.java)
+		assertThat(runBlocking { (target as Flow<*>).toList() }).contains(1, 2, 3)
 	}
 
 	private fun getAdapter(reactiveType: KClass<*>): ReactiveAdapter {

spring-core/src/test/kotlin/org/springframework/core/KotlinReflectionParameterNameDiscovererTests.kt

@@ -16,10 +16,9 @@
 
 package org.springframework.core
 
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 
-import org.hamcrest.CoreMatchers.`is`
-import org.hamcrest.MatcherAssert.assertThat
 import org.springframework.util.ReflectionUtils
 
 /**
@@ -33,21 +32,21 @@ class KotlinReflectionParameterNameDiscovererTests {
 	fun getParameterNamesOnInterface() {
 		val method = ReflectionUtils.findMethod(MessageService::class.java,"sendMessage", String::class.java)!!
 		val actualParams = parameterNameDiscoverer.getParameterNames(method)
-		assertThat(actualParams, `is`(arrayOf("message")))
+		assertThat(actualParams).contains("message")
 	}
 
 	@Test
 	fun getParameterNamesOnClass() {
 		val method = ReflectionUtils.findMethod(MessageServiceImpl::class.java,"sendMessage", String::class.java)!!
 		val actualParams = parameterNameDiscoverer.getParameterNames(method)
-		assertThat(actualParams, `is`(arrayOf("message")))
+		assertThat(actualParams).contains("message")
 	}
 
 	@Test
 	fun getParameterNamesOnExtensionMethod() {
 		val method = ReflectionUtils.findMethod(UtilityClass::class.java, "identity", String::class.java)!!
 		val actualParams = parameterNameDiscoverer.getParameterNames(method)!!
-		assertThat(actualParams, `is`(arrayOf("\$receiver")))
+		assertThat(actualParams).contains("\$receiver")
 	}
 
 	interface MessageService {

spring-jdbc/src/test/kotlin/org/springframework/jdbc/core/JdbcOperationsExtensionsTests.kt

@@ -21,8 +21,7 @@ import java.sql.*
 import io.mockk.every
 import io.mockk.mockk
 import io.mockk.verify
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertNull
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 
 /**
@@ -40,21 +39,21 @@ class JdbcOperationsExtensionsTests {
 	@Test
 	fun `queryForObject with reified type parameters`() {
 		every { template.queryForObject(sql, any<Class<Int>>()) } returns 2
-		assertEquals(2, template.queryForObject<Int>(sql))
+		assertThat(template.queryForObject<Int>(sql)).isEqualTo(2)
 		verify { template.queryForObject(sql, any<Class<Int>>()) }
 	}
 
 	@Test
 	fun `queryForObject with RowMapper-like function`() {
 		every { template.queryForObject(sql, any<RowMapper<Int>>(), any<Int>()) } returns 2
-		assertEquals(2, template.queryForObject(sql, 3) { rs: ResultSet, _: Int -> rs.getInt(1) })
+		assertThat(template.queryForObject(sql, 3) { rs: ResultSet, _: Int -> rs.getInt(1) }).isEqualTo(2)
 		verify { template.queryForObject(eq(sql), any<RowMapper<Int>>(), eq(3)) }
 	}
 
 	@Test  // gh-22682
 	fun `queryForObject with nullable RowMapper-like function`() {
 		every { template.queryForObject(sql, any<RowMapper<Int>>(), 3) } returns null
-		assertNull(template.queryForObject(sql, 3) { _, _ -> null as Int? })
+		assertThat(template.queryForObject(sql, 3) { _, _ -> null as Int? }).isNull()
 		verify { template.queryForObject(eq(sql), any<RowMapper<Int?>>(), eq(3)) }
 	}
 
@@ -63,7 +62,7 @@ class JdbcOperationsExtensionsTests {
 		val args = arrayOf(3)
 		val argTypes = intArrayOf(JDBCType.INTEGER.vendorTypeNumber)
 		every { template.queryForObject(sql, args, argTypes, any<Class<Int>>()) } returns 2
-		assertEquals(2, template.queryForObject<Int>(sql, args, argTypes))
+		assertThat(template.queryForObject<Int>(sql, args, argTypes)).isEqualTo(2)
 		verify { template.queryForObject(sql, args, argTypes, any<Class<Int>>()) }
 	}
 
@@ -71,7 +70,7 @@ class JdbcOperationsExtensionsTests {
 	fun `queryForObject with reified type parameters and args`() {
 		val args = arrayOf(3)
 		every { template.queryForObject(sql, args, any<Class<Int>>()) } returns 2
-		assertEquals(2, template.queryForObject<Int>(sql, args))
+		assertThat(template.queryForObject<Int>(sql, args)).isEqualTo(2)
 		verify { template.queryForObject(sql, args, any<Class<Int>>()) }
 	}
 
@@ -79,7 +78,7 @@ class JdbcOperationsExtensionsTests {
 	fun `queryForList with reified type parameters`() {
 		val list = listOf(1, 2, 3)
 		every { template.queryForList(sql, any<Class<Int>>()) } returns list
-		assertEquals(list, template.queryForList<Int>(sql))
+		assertThat(template.queryForList<Int>(sql)).isEqualTo(list)
 		verify { template.queryForList(sql, any<Class<Int>>()) }
 	}
 
@@ -89,7 +88,7 @@ class JdbcOperationsExtensionsTests {
 		val args = arrayOf(3)
 		val argTypes = intArrayOf(JDBCType.INTEGER.vendorTypeNumber)
 		every { template.queryForList(sql, args, argTypes, any<Class<Int>>()) } returns list
-		assertEquals(list, template.queryForList<Int>(sql, args, argTypes))
+		assertThat(template.queryForList<Int>(sql, args, argTypes)).isEqualTo(list)
 		verify { template.queryForList(sql, args, argTypes, any<Class<Int>>()) }
 	}
 
@@ -105,17 +104,17 @@ class JdbcOperationsExtensionsTests {
 	@Test
 	fun `query with ResultSetExtractor-like function`() {
 		every { template.query(eq(sql), any<ResultSetExtractor<Int>>(), eq(3)) } returns 2
-		assertEquals(2, template.query<Int>(sql, 3) { rs ->
+		assertThat(template.query<Int>(sql, 3) { rs ->
 			rs.next()
 			rs.getInt(1)
-		})
+		}).isEqualTo(2)
 		verify { template.query(eq(sql), any<ResultSetExtractor<Int>>(), eq(3)) }
 	}
 
 	@Test  // gh-22682
 	fun `query with nullable ResultSetExtractor-like function`() {
 		every { template.query(eq(sql), any<ResultSetExtractor<Int?>>(), eq(3)) } returns null
-		assertNull(template.query<Int?>(sql, 3) { _ -> null })
+		assertThat(template.query<Int?>(sql, 3) { _ -> null }).isNull()
 		verify { template.query(eq(sql), any<ResultSetExtractor<Int?>>(), eq(3)) }
 	}
 
@@ -124,7 +123,7 @@ class JdbcOperationsExtensionsTests {
 	fun `query with RowCallbackHandler-like function`() {
 		every { template.query(sql, ofType<RowCallbackHandler>(), 3) } returns Unit
 		template.query(sql, 3) { rs ->
-			assertEquals(22, rs.getInt(1))
+			assertThat(rs.getInt(1)).isEqualTo(22)
 		}
 		verify { template.query(sql, ofType<RowCallbackHandler>(), 3) }
 	}
@@ -133,9 +132,9 @@ class JdbcOperationsExtensionsTests {
 	fun `query with RowMapper-like function`() {
 		val list = listOf(1, 2, 3)
 		every { template.query(sql, ofType<RowMapper<*>>(), 3) } returns list
-		assertEquals(list, template.query(sql, 3) { rs, _ ->
+		assertThat(template.query(sql, 3) { rs, _ ->
 			rs.getInt(1)
-		})
+		}).isEqualTo(list)
 		verify { template.query(sql, ofType<RowMapper<*>>(), 3) }
 	}
 

spring-jdbc/src/test/kotlin/org/springframework/jdbc/core/namedparam/MapSqlParameterSourceExtensionsTests.kt

@@ -16,9 +16,9 @@
 
 package org.springframework.jdbc.core.namedparam
 
+import org.assertj.core.api.Assertions.assertThat
 import java.sql.JDBCType
 
-import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Test
 
 /**
@@ -32,24 +32,24 @@ class MapSqlParameterSourceExtensionsTests {
 	fun `setter with value`() {
 		val source = MapSqlParameterSource()
 		source["foo"] = 2
-		assertEquals(2, source.getValue("foo"))
+		assertThat(source.getValue("foo")).isEqualTo(2)
 	}
 
 	@Test
 	fun `setter with value and type`() {
 		val source = MapSqlParameterSource()
 		source["foo", JDBCType.INTEGER.vendorTypeNumber] = 2
-		assertEquals(2, source.getValue("foo"))
-		assertEquals(JDBCType.INTEGER.vendorTypeNumber, source.getSqlType("foo"))
+		assertThat(source.getValue("foo")).isEqualTo(2)
+		assertThat(source.getSqlType("foo")).isEqualTo(JDBCType.INTEGER.vendorTypeNumber)
 	}
 
 	@Test
 	fun `setter with value, type and type name`() {
 		val source = MapSqlParameterSource()
 		source["foo", JDBCType.INTEGER.vendorTypeNumber, "INT"] = 2
-		assertEquals(2, source.getValue("foo"))
-		assertEquals(JDBCType.INTEGER.vendorTypeNumber, source.getSqlType("foo"))
-		assertEquals("INT", source.getTypeName("foo"))
+		assertThat(source.getValue("foo")).isEqualTo(2)
+		assertThat(source.getSqlType("foo")).isEqualTo(JDBCType.INTEGER.vendorTypeNumber)
+		assertThat(source.getTypeName("foo")).isEqualTo("INT")
 	}
 
 }

spring-messaging/src/main/kotlin/org/springframework/messaging/rsocket/RSocketRequesterExtensions.kt

@@ -17,7 +17,6 @@
 package org.springframework.messaging.rsocket
 
 import io.rsocket.transport.ClientTransport
-import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.reactive.awaitFirstOrNull
 import kotlinx.coroutines.reactive.awaitSingle
@@ -90,7 +89,6 @@ inline fun <reified T : Any> RSocketRequester.RequestSpec.dataWithType(publisher
  * @author Sebastien Deleuze
  * @since 5.2
  */
-@ExperimentalCoroutinesApi
 inline fun <reified T : Any> RSocketRequester.RequestSpec.dataWithType(flow: Flow<T>): RSocketRequester.ResponseSpec =
 		data(flow, object : ParameterizedTypeReference<T>() {})
 
@@ -120,7 +118,6 @@ suspend inline fun <reified T : Any> RSocketRequester.ResponseSpec.retrieveAndAw
  * @author Sebastien Deleuze
  * @since 5.2
  */
-@ExperimentalCoroutinesApi
 inline fun <reified T : Any> RSocketRequester.ResponseSpec.retrieveFlow(): Flow<T> =
 		retrieveFlux(object : ParameterizedTypeReference<T>() {}).asFlow()
 

spring-messaging/src/test/kotlin/org/springframework/messaging/rsocket/RSocketRequesterExtensionsTests.kt

@@ -1,12 +1,27 @@
+/*
+ * Copyright 2002-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package org.springframework.messaging.rsocket
 
 import io.mockk.every
 import io.mockk.mockk
-import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.toList
 import kotlinx.coroutines.runBlocking
-import org.junit.jupiter.api.Assertions.assertEquals
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.mockito.ArgumentMatchers.anyInt
 import org.reactivestreams.Publisher
@@ -20,7 +35,6 @@ import java.util.concurrent.CompletableFuture
  *
  * @author Sebastien Deleuze
  */
-@ExperimentalCoroutinesApi
 class RSocketRequesterExtensionsTests {
 
 	private val stringTypeRefMatcher: (ParameterizedTypeReference<*>) -> Boolean  = { it.type == String::class.java }
@@ -31,7 +45,7 @@ class RSocketRequesterExtensionsTests {
 		val builder = mockk<RSocketRequester.Builder>()
 		every { builder.connect(any()) } returns Mono.just(requester)
 		runBlocking {
-			assertEquals(requester, builder.connectAndAwait(mockk()))
+			assertThat(builder.connectAndAwait(mockk())).isEqualTo(requester)
 		}
 	}
 
@@ -42,7 +56,7 @@ class RSocketRequesterExtensionsTests {
 		val builder = mockk<RSocketRequester.Builder>()
 		every { builder.connectTcp(host, anyInt()) } returns Mono.just(requester)
 		runBlocking {
-			assertEquals(requester, builder.connectTcpAndAwait(host, 0))
+			assertThat(builder.connectTcpAndAwait(host, 0)).isEqualTo(requester)
 		}
 	}
 
@@ -52,7 +66,7 @@ class RSocketRequesterExtensionsTests {
 		val builder = mockk<RSocketRequester.Builder>()
 		every { builder.connectWebSocket(any()) } returns Mono.just(requester)
 		runBlocking {
-			assertEquals(requester, builder.connectWebSocketAndAwait(mockk()))
+			assertThat(builder.connectWebSocketAndAwait(mockk())).isEqualTo(requester)
 		}
 	}
 
@@ -62,7 +76,7 @@ class RSocketRequesterExtensionsTests {
 		val responseSpec = mockk<RSocketRequester.ResponseSpec>()
 		val data = mockk<Publisher<String>>()
 		every { requestSpec.data(any<Publisher<String>>(), match<ParameterizedTypeReference<*>>(stringTypeRefMatcher)) } returns responseSpec
-		assertEquals(responseSpec, requestSpec.dataWithType(data))
+		assertThat(requestSpec.dataWithType(data)).isEqualTo(responseSpec)
 	}
 
 	@Test
@@ -71,7 +85,7 @@ class RSocketRequesterExtensionsTests {
 		val responseSpec = mockk<RSocketRequester.ResponseSpec>()
 		val data = mockk<Flow<String>>()
 		every { requestSpec.data(any<Publisher<String>>(), match<ParameterizedTypeReference<*>>(stringTypeRefMatcher)) } returns responseSpec
-		assertEquals(responseSpec, requestSpec.dataWithType(data))
+		assertThat(requestSpec.dataWithType(data)).isEqualTo(responseSpec)
 	}
 
 	@Test
@@ -80,7 +94,7 @@ class RSocketRequesterExtensionsTests {
 		val responseSpec = mockk<RSocketRequester.ResponseSpec>()
 		val data = mockk<CompletableFuture<String>>()
 		every { requestSpec.data(any<Publisher<String>>(), match<ParameterizedTypeReference<*>>(stringTypeRefMatcher)) } returns responseSpec
-		assertEquals(responseSpec, requestSpec.dataWithType<String>(data))
+		assertThat(requestSpec.dataWithType<String>(data)).isEqualTo(responseSpec)
 	}
 
 	@Test
@@ -88,7 +102,7 @@ class RSocketRequesterExtensionsTests {
 		val requestSpec = mockk<RSocketRequester.RequestSpec>()
 		val responseSpec = mockk<RSocketRequester.ResponseSpec>()
 		every { requestSpec.data(any()) } returns responseSpec
-		assertEquals(responseSpec, requestSpec.data(mockk()))
+		assertThat(requestSpec.data(mockk())).isEqualTo(responseSpec)
 	}
 
 	@Test
@@ -106,7 +120,7 @@ class RSocketRequesterExtensionsTests {
 		val responseSpec = mockk<RSocketRequester.ResponseSpec>()
 		every { responseSpec.retrieveMono(match<ParameterizedTypeReference<*>>(stringTypeRefMatcher)) } returns Mono.just("foo")
 		runBlocking {
-			assertEquals(response, responseSpec.retrieveAndAwait<String>())
+			assertThat(responseSpec.retrieveAndAwait<String>()).isEqualTo(response)
 		}
 	}
 
@@ -115,7 +129,7 @@ class RSocketRequesterExtensionsTests {
 		val responseSpec = mockk<RSocketRequester.ResponseSpec>()
 		every { responseSpec.retrieveFlux(match<ParameterizedTypeReference<*>>(stringTypeRefMatcher)) } returns Flux.just("foo", "bar")
 		runBlocking {
-			assertEquals(listOf("foo", "bar"), responseSpec.retrieveFlow<String>().toList())
+			assertThat(responseSpec.retrieveFlow<String>().toList()).contains("foo", "bar")
 		}
 	}
 
@@ -124,7 +138,7 @@ class RSocketRequesterExtensionsTests {
 		val responseSpec = mockk<RSocketRequester.ResponseSpec>()
 		every { responseSpec.retrieveMono(match<ParameterizedTypeReference<*>>(stringTypeRefMatcher)) } returns Mono.just("foo")
 		runBlocking {
-			assertEquals("foo", responseSpec.retrieveMono<String>().block())
+			assertThat(responseSpec.retrieveMono<String>().block()).isEqualTo("foo")
 		}
 	}
 
@@ -133,7 +147,7 @@ class RSocketRequesterExtensionsTests {
 		val responseSpec = mockk<RSocketRequester.ResponseSpec>()
 		every { responseSpec.retrieveFlux(match<ParameterizedTypeReference<*>>(stringTypeRefMatcher)) } returns Flux.just("foo", "bar")
 		runBlocking {
-			assertEquals(listOf("foo", "bar"), responseSpec.retrieveFlux<String>().collectList().block())
+			assertThat(responseSpec.retrieveFlux<String>().collectList().block()).contains("foo", "bar")
 		}
 	}
 

spring-messaging/src/test/kotlin/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandlerKotlinTests.kt

@@ -17,6 +17,7 @@
 package org.springframework.messaging.simp.annotation.support
 
 import io.mockk.mockk
+import org.assertj.core.api.Assertions.assertThat
 import java.util.Collections
 import java.util.HashMap
 
@@ -36,7 +37,6 @@ import org.springframework.messaging.simp.SimpMessagingTemplate
 import org.springframework.messaging.support.MessageBuilder
 import org.springframework.stereotype.Controller
 
-import org.junit.jupiter.api.Assertions.*
 import org.springframework.messaging.MessageHandlingException
 import org.springframework.messaging.handler.annotation.MessageExceptionHandler
 
@@ -70,8 +70,8 @@ class SimpAnnotationMethodMessageHandlerKotlinTests {
         val message = createMessage("/nullableHeader", Collections.singletonMap("foo", "bar"))
         messageHandler.registerHandler(testController)
         messageHandler.handleMessage(message)
-        assertNull(testController.exception)
-        assertEquals("bar", testController.header)
+        assertThat(testController.exception).isNull()
+		assertThat(testController.header).isEqualTo("bar")
     }
 
     @Test
@@ -79,8 +79,8 @@ class SimpAnnotationMethodMessageHandlerKotlinTests {
         val message = createMessage("/nullableHeader", Collections.emptyMap())
         messageHandler.registerHandler(testController)
         messageHandler.handleMessage(message)
-        assertNull(testController.exception)
-        assertNull(testController.header)
+		assertThat(testController.exception).isNull()
+		assertThat(testController.header).isNull()
     }
 
     @Test
@@ -88,7 +88,7 @@ class SimpAnnotationMethodMessageHandlerKotlinTests {
         val message = createMessage("/nonNullableHeader", Collections.singletonMap("foo", "bar"))
         messageHandler.registerHandler(testController)
         messageHandler.handleMessage(message)
-        assertEquals("bar", testController.header)
+		assertThat(testController.header).isEqualTo("bar")
     }
 
     @Test
@@ -96,8 +96,8 @@ class SimpAnnotationMethodMessageHandlerKotlinTests {
         val message = createMessage("/nonNullableHeader", Collections.emptyMap())
         messageHandler.registerHandler(testController)
         messageHandler.handleMessage(message)
-        assertNotNull(testController.exception)
-        assertTrue(testController.exception is MessageHandlingException)
+        assertThat(testController.exception).isNotNull()
+        assertThat(testController.exception).isInstanceOf(MessageHandlingException::class.java)
     }
 
     @Test
@@ -105,8 +105,8 @@ class SimpAnnotationMethodMessageHandlerKotlinTests {
         val message = createMessage("/nullableHeaderNotRequired", Collections.singletonMap("foo", "bar"))
         messageHandler.registerHandler(testController)
         messageHandler.handleMessage(message)
-        assertNull(testController.exception)
-        assertEquals("bar", testController.header)
+		assertThat(testController.exception).isNull()
+		assertThat(testController.header).isEqualTo("bar")
     }
 
     @Test
@@ -114,8 +114,8 @@ class SimpAnnotationMethodMessageHandlerKotlinTests {
         val message = createMessage("/nullableHeaderNotRequired", Collections.emptyMap())
         messageHandler.registerHandler(testController)
         messageHandler.handleMessage(message)
-        assertNull(testController.exception)
-        assertNull(testController.header)
+		assertThat(testController.exception).isNull()
+		assertThat(testController.header).isNull()
     }
 
     @Test
@@ -123,7 +123,7 @@ class SimpAnnotationMethodMessageHandlerKotlinTests {
         val message = createMessage("/nonNullableHeaderNotRequired", Collections.singletonMap("foo", "bar"))
         messageHandler.registerHandler(testController)
         messageHandler.handleMessage(message)
-        assertEquals("bar", testController.header)
+		assertThat(testController.header).isEqualTo("bar")
     }
 
     @Test
@@ -131,8 +131,8 @@ class SimpAnnotationMethodMessageHandlerKotlinTests {
         val message = createMessage("/nonNullableHeaderNotRequired", Collections.emptyMap())
         messageHandler.registerHandler(testController)
         messageHandler.handleMessage(message)
-        assertNotNull(testController.exception)
-        assertTrue(testController.exception is IllegalArgumentException)
+        assertThat(testController.exception).isNotNull()
+		assertThat(testController.exception).isInstanceOf(IllegalArgumentException::class.java)
     }
 
     private fun createMessage(destination: String, headers: Map<String, String?>): Message<ByteArray> {

spring-test/src/test/kotlin/org/springframework/test/web/reactive/server/WebTestClientExtensionsTests.kt

@@ -20,7 +20,7 @@ import io.mockk.mockk
 import io.mockk.verify
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
-import org.junit.jupiter.api.Assertions.assertEquals
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.reactivestreams.Publisher
 import org.springframework.core.ParameterizedTypeReference
@@ -80,7 +80,7 @@ class WebTestClientExtensionsTests {
 		WebTestClient
 				.bindToRouterFunction( router { GET("/") { ok().bodyValue("foo") } } )
 				.build()
-				.get().uri("/").exchange().expectBody<String>().consumeWith { assertEquals("foo", it.responseBody) }
+				.get().uri("/").exchange().expectBody<String>().consumeWith { assertThat(it.responseBody).isEqualTo("foo") }
 	}
 
 	@Test
@@ -88,7 +88,7 @@ class WebTestClientExtensionsTests {
 		WebTestClient
 				.bindToRouterFunction( router { GET("/") { ok().bodyValue("foo") } } )
 				.build()
-				.get().uri("/").exchange().expectBody<String>().returnResult().apply { assertEquals("foo", responseBody) }
+				.get().uri("/").exchange().expectBody<String>().returnResult().apply { assertThat(responseBody).isEqualTo("foo") }
 	}
 
 	@Test

spring-test/src/test/kotlin/org/springframework/test/web/servlet/MockMvcExtensionsTests.kt

@@ -16,10 +16,9 @@
 
 package org.springframework.test.web.servlet
 
+import org.assertj.core.api.Assertions.*
 import org.hamcrest.CoreMatchers
-import org.junit.jupiter.api.Assertions.assertTrue
 import org.junit.jupiter.api.Test
-import org.junit.jupiter.api.assertThrows
 import org.springframework.http.HttpMethod
 import org.springframework.http.HttpStatus
 import org.springframework.http.MediaType.*
@@ -81,8 +80,8 @@ class MockMvcExtensionsTests {
 		}.andDo {
 			handle(handler)
 		}
-		assertTrue(matcherInvoked)
-		assertTrue(handlerInvoked)
+		assertThat(matcherInvoked).isTrue()
+		assertThat(handlerInvoked).isTrue()
 	}
 
 	@Test
@@ -125,21 +124,20 @@ class MockMvcExtensionsTests {
 		mockMvc.get("/person/$name") {
 			accept = APPLICATION_JSON
 		}.andExpect {
-			assertThrows<AssertionError> { content { contentType(APPLICATION_ATOM_XML) } }
-			assertThrows<AssertionError> { content { string("Wrong") } }
-			assertThrows<AssertionError> { jsonPath("name", CoreMatchers.`is`("Wrong")) }
-			assertThrows<AssertionError> { content { json("""{"name":"wrong"}""") } }
-			assertThrows<AssertionError> { jsonPath("name") { value("wrong") } }
-			assertThrows<AssertionError> { cookie { value("name", "wrong") } }
-			assertThrows<AssertionError> { flash { attribute<String>("name", "wrong") } }
-			assertThrows<AssertionError> { header { stringValues("name", "wrong") } }
-			assertThrows<AssertionError> { model { attributeExists("name", "wrong") } }
-			assertThrows<AssertionError> { redirectedUrl("wrong/Url") }
-			assertThrows<AssertionError> { redirectedUrlPattern("wrong/Url") }
-			assertThrows<AssertionError> { redirectedUrlPattern("wrong/Url") }
-			assertThrows<AssertionError> { status { isAccepted } }
-			assertThrows<AssertionError> { view { name("wrongName") } }
-			assertThrows<AssertionError> { jsonPath("name") { value("wrong") } }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { content { contentType(APPLICATION_ATOM_XML) } }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { content { string("Wrong") } }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { jsonPath("name", CoreMatchers.`is`("Wrong")) }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { content { json("""{"name":"wrong"}""") } }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { jsonPath("name") { value("wrong") } }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { cookie { value("name", "wrong") } }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { flash { attribute<String>("name", "wrong") } }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { header { stringValues("name", "wrong") } }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { model { attributeExists("name", "wrong") } }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { redirectedUrl("wrong/Url") }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { redirectedUrlPattern("wrong/Url") }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { status { isAccepted } }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { view { name("wrongName") } }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { jsonPath("name") { value("wrong") } }
 		}
 	}
 
@@ -149,7 +147,7 @@ class MockMvcExtensionsTests {
 			accept = APPLICATION_XML
 		}.andExpect {
 			status { isOk }
-			assertThrows<AssertionError> { xpath("//wrong") { nodeCount(1) } }
+			assertThatExceptionOfType(AssertionError::class.java).isThrownBy { xpath("//wrong") { nodeCount(1) } }
 		}.andDo {
 			print()
 		}

spring-web/src/test/kotlin/org/springframework/web/client/RestOperationsExtensionsTests.kt

@@ -19,7 +19,7 @@ package org.springframework.web.client
 import io.mockk.every
 import io.mockk.mockk
 import io.mockk.verify
-import org.junit.jupiter.api.Assertions.assertEquals
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.core.ParameterizedTypeReference
 import org.springframework.http.*
@@ -47,7 +47,7 @@ class RestOperationsExtensionsTests {
 		val var1 = "var1"
 		val var2 = "var2"
 		every { template.getForObject(url, Foo::class.java, var1, var2) } returns foo
-		assertEquals(foo, template.getForObject<Foo>(url, var1, var2))
+		assertThat(template.getForObject<Foo>(url, var1, var2)).isEqualTo(foo)
 		verify { template.getForObject(url, Foo::class.java, var1, var2) }
 	}
 
@@ -56,7 +56,7 @@ class RestOperationsExtensionsTests {
 		val url = "https://spring.io"
 		val vars = mapOf(Pair("key1", "value1"), Pair("key2", "value2"))
 		every { template.getForObject(url, Foo::class.java, vars) } returns foo
-		assertEquals(foo, template.getForObject<Foo>(url, vars))
+		assertThat(template.getForObject<Foo>(url, vars)).isEqualTo(foo)
 		verify { template.getForObject(url, Foo::class.java, vars) }
 	}
 
@@ -64,7 +64,7 @@ class RestOperationsExtensionsTests {
 	fun `getForObject with reified type parameters and URI`() {
 		val url = URI("https://spring.io")
 		every { template.getForObject(url, Foo::class.java) } returns foo
-		assertEquals(foo, template.getForObject<Foo>(url))
+		assertThat(template.getForObject<Foo>(url)).isEqualTo(foo)
 		verify { template.getForObject(url, Foo::class.java) }
 	}
 
@@ -72,7 +72,7 @@ class RestOperationsExtensionsTests {
 	fun `getForEntity with reified type parameters, String and URI`() {
 		val url = URI("https://spring.io")
 		every { template.getForEntity(url, Foo::class.java) } returns entity
-		assertEquals(entity, template.getForEntity<Foo>(url))
+		assertThat(template.getForEntity<Foo>(url)).isEqualTo(entity)
 		verify { template.getForEntity(url, Foo::class.java) }
 	}
 
@@ -82,7 +82,7 @@ class RestOperationsExtensionsTests {
 		val var1 = "var1"
 		val var2 = "var2"
 		every { template.getForEntity(url, Foo::class.java, var1, var2) } returns entity
-		assertEquals(entity, template.getForEntity<Foo>(url, var1, var2))
+		assertThat(template.getForEntity<Foo>(url, var1, var2)).isEqualTo(entity)
 		verify { template.getForEntity(url, Foo::class.java, var1, var2) }
 	}
 
@@ -91,7 +91,7 @@ class RestOperationsExtensionsTests {
 		val url = "https://spring.io"
 		val vars = mapOf(Pair("key1", "value1"), Pair("key2", "value2"))
 		every { template.getForEntity(url, Foo::class.java, vars) } returns entity
-		assertEquals(entity, template.getForEntity<Foo>(url, vars))
+		assertThat(template.getForEntity<Foo>(url, vars)).isEqualTo(entity)
 		verify { template.getForEntity(url, Foo::class.java, vars) }
 	}
 
@@ -102,7 +102,7 @@ class RestOperationsExtensionsTests {
 		val var1 = "var1"
 		val var2 = "var2"
 		every { template.patchForObject(url, body, Foo::class.java, var1, var2) } returns foo
-		assertEquals(foo, template.patchForObject<Foo>(url, body, var1, var2))
+		assertThat(template.patchForObject<Foo>(url, body, var1, var2)).isEqualTo(foo)
 		verify { template.patchForObject(url, body, Foo::class.java, var1, var2) }
 	}
 
@@ -112,7 +112,7 @@ class RestOperationsExtensionsTests {
 		val body: Any = "body"
 		val vars = mapOf(Pair("key1", "value1"), Pair("key2", "value2"))
 		every { template.patchForObject(url, body, Foo::class.java, vars) } returns foo
-		assertEquals(foo, template.patchForObject<Foo>(url, body, vars))
+		assertThat(template.patchForObject<Foo>(url, body, vars)).isEqualTo(foo)
 		verify { template.patchForObject(url, body, Foo::class.java, vars) }
 	}
 
@@ -121,7 +121,7 @@ class RestOperationsExtensionsTests {
 		val url = "https://spring.io"
 		val body: Any = "body"
 		every { template.patchForObject(url, body, Foo::class.java) } returns foo
-		assertEquals(foo, template.patchForObject<Foo>(url, body))
+		assertThat(template.patchForObject<Foo>(url, body)).isEqualTo(foo)
 		verify { template.patchForObject(url, body, Foo::class.java) }
 	}
 
@@ -129,7 +129,7 @@ class RestOperationsExtensionsTests {
 	fun `patchForObject with reified type parameters`() {
 		val url = "https://spring.io"
 		every { template.patchForObject(url, null, Foo::class.java) } returns foo
-		assertEquals(foo, template.patchForObject<Foo>(url))
+		assertThat(template.patchForObject<Foo>(url)).isEqualTo(foo)
 		verify { template.patchForObject(url, null, Foo::class.java) }
 	}
 
@@ -140,7 +140,7 @@ class RestOperationsExtensionsTests {
 		val var1 = "var1"
 		val var2 = "var2"
 		every { template.postForObject(url, body, Foo::class.java, var1, var2) } returns foo
-		assertEquals(foo, template.postForObject<Foo>(url, body, var1, var2))
+		assertThat(template.postForObject<Foo>(url, body, var1, var2)).isEqualTo(foo)
 		verify { template.postForObject(url, body, Foo::class.java, var1, var2) }
 	}
 
@@ -150,7 +150,7 @@ class RestOperationsExtensionsTests {
 		val body: Any = "body"
 		val vars = mapOf(Pair("key1", "value1"), Pair("key2", "value2"))
 		every { template.postForObject(url, body, Foo::class.java, vars) } returns foo
-		assertEquals(foo, template.postForObject<Foo>(url, body, vars))
+		assertThat(template.postForObject<Foo>(url, body, vars)).isEqualTo(foo)
 		verify { template.postForObject(url, body, Foo::class.java, vars) }
 	}
 
@@ -159,7 +159,7 @@ class RestOperationsExtensionsTests {
 		val url = "https://spring.io"
 		val body: Any = "body"
 		every { template.postForObject(url, body, Foo::class.java) } returns foo
-		assertEquals(foo, template.postForObject<Foo>(url, body))
+		assertThat(template.postForObject<Foo>(url, body)).isEqualTo(foo)
 		verify { template.postForObject(url, body, Foo::class.java) }
 	}
 
@@ -167,7 +167,7 @@ class RestOperationsExtensionsTests {
 	fun `postForObject with reified type parameters`() {
 		val url = "https://spring.io"
 		every { template.postForObject(url, null, Foo::class.java) } returns foo
-		assertEquals(foo, template.postForObject<Foo>(url))
+		assertThat(template.postForObject<Foo>(url)).isEqualTo(foo)
 		verify { template.postForObject(url, null, Foo::class.java) }
 	}
 
@@ -178,7 +178,7 @@ class RestOperationsExtensionsTests {
 		val var1 = "var1"
 		val var2 = "var2"
 		every { template.postForEntity(url, body, Foo::class.java, var1, var2) } returns entity
-		assertEquals(entity, template.postForEntity<Foo>(url, body, var1, var2))
+		assertThat(template.postForEntity<Foo>(url, body, var1, var2)).isEqualTo(entity)
 		verify { template.postForEntity(url, body, Foo::class.java, var1, var2) }
 	}
 
@@ -188,7 +188,7 @@ class RestOperationsExtensionsTests {
 		val body: Any = "body"
 		val vars = mapOf(Pair("key1", "value1"), Pair("key2", "value2"))
 		every { template.postForEntity(url, body, Foo::class.java, vars) } returns entity
-		assertEquals(entity, template.postForEntity<Foo>(url, body, vars))
+		assertThat(template.postForEntity<Foo>(url, body, vars)).isEqualTo(entity)
 		verify { template.postForEntity(url, body, Foo::class.java, vars) }
 	}
 
@@ -197,7 +197,7 @@ class RestOperationsExtensionsTests {
 		val url = "https://spring.io"
 		val body: Any = "body"
 		every { template.postForEntity(url, body, Foo::class.java) } returns entity
-		assertEquals(entity, template.postForEntity<Foo>(url, body))
+		assertThat(template.postForEntity<Foo>(url, body)).isEqualTo(entity)
 		verify { template.postForEntity(url, body, Foo::class.java) }
 	}
 
@@ -205,7 +205,7 @@ class RestOperationsExtensionsTests {
 	fun `postForEntity with reified type parameters`() {
 		val url = "https://spring.io"
 		every  { template.postForEntity(url, null, Foo::class.java) } returns entity
-		assertEquals(entity, template.postForEntity<Foo>(url))
+		assertThat(template.postForEntity<Foo>(url)).isEqualTo(entity)
 		verify { template.postForEntity(url, null, Foo::class.java) }
 	}
 
@@ -218,7 +218,7 @@ class RestOperationsExtensionsTests {
 		val entityList = mockk<ResponseEntity<List<Foo>>>()
 		val responseType = object : ParameterizedTypeReference<List<Foo>>() {}
 		every { template.exchange(url, method, entity, responseType, var1, var2) } returns entityList
-		assertEquals(entityList, template.exchange<List<Foo>>(url, method, entity, var1, var2))
+		assertThat(template.exchange<List<Foo>>(url, method, entity, var1, var2)).isEqualTo(entityList)
 		verify { template.exchange(url, method, entity, responseType, var1, var2) }
 	}
 
@@ -231,7 +231,7 @@ class RestOperationsExtensionsTests {
 		val entityList = mockk<ResponseEntity<List<Foo>>>()
 		val responseType = object : ParameterizedTypeReference<List<Foo>>() {}
 		every { template.exchange(url, method, entity, responseType, vars) } returns entityList
-		assertEquals(entityList, template.exchange<List<Foo>>(url, method, entity, vars))
+		assertThat(template.exchange<List<Foo>>(url, method, entity, vars)).isEqualTo(entityList)
 		verify { template.exchange(url, method, entity, responseType, vars) }
 	}
 
@@ -243,7 +243,7 @@ class RestOperationsExtensionsTests {
 		val entityList = mockk<ResponseEntity<List<Foo>>>()
 		val responseType = object : ParameterizedTypeReference<List<Foo>>() {}
 		every { template.exchange(url, method, entity, responseType) } returns entityList
-		assertEquals(entityList, template.exchange<List<Foo>>(url, method, entity))
+		assertThat(template.exchange<List<Foo>>(url, method, entity)).isEqualTo(entityList)
 		verify { template.exchange(url, method, entity, responseType) }
 	}
 
@@ -254,7 +254,7 @@ class RestOperationsExtensionsTests {
 		val entityList = mockk<ResponseEntity<List<Foo>>>()
 		val responseType = object : ParameterizedTypeReference<List<Foo>>() {}
 		every { template.exchange(url, method, null, responseType) } returns entityList
-		assertEquals(entityList, template.exchange<List<Foo>>(url, method))
+		assertThat(template.exchange<List<Foo>>(url, method)).isEqualTo(entityList)
 		verify { template.exchange(url, method, null, responseType) }
 	}
 
@@ -264,7 +264,7 @@ class RestOperationsExtensionsTests {
 		val entityList = mockk<ResponseEntity<List<Foo>>>()
 		val responseType = object : ParameterizedTypeReference<List<Foo>>() {}
 		every { template.exchange(entity, responseType) } returns entityList
-		assertEquals(entityList, template.exchange<List<Foo>>(entity))
+		assertThat(template.exchange<List<Foo>>(entity)).isEqualTo(entityList)
 		verify { template.exchange(entity, responseType) }
 	}
 
@@ -276,9 +276,8 @@ class RestOperationsExtensionsTests {
 				if (method.parameterTypes.contains(kClass.java)) {
 					val parameters = mutableListOf<Class<*>>(RestOperations::class.java).apply { addAll(method.parameterTypes.filter { it !=  kClass.java }) }
 					val f = extensions.getDeclaredMethod(method.name, *parameters.toTypedArray()).kotlinFunction!!
-					assertEquals(1, f.typeParameters.size)
-					System.out.println(method.name + f.typeParameters)
-					assertEquals(listOf(Any::class.createType(nullable = true)), f.typeParameters[0].upperBounds, "Failed: " + method.name)
+					assertThat(f.typeParameters.size).isEqualTo(1)
+					assertThat(f.typeParameters[0].upperBounds).isEqualTo(listOf(Any::class.createType(nullable = true)))
 				}
 			}
 		}

spring-web/src/test/kotlin/org/springframework/web/method/annotation/RequestParamMethodArgumentResolverKotlinTests.kt

@@ -16,9 +16,9 @@
 
 package org.springframework.web.method.annotation
 
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertNull
-import org.junit.jupiter.api.fail
+import org.assertj.core.api.Assertions
+import org.assertj.core.api.Assertions.assertThat
+import org.assertj.core.api.Assertions.assertThatExceptionOfType
 import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.Test
 import org.springframework.core.MethodParameter
@@ -94,43 +94,39 @@ class RequestParamMethodArgumentResolverKotlinTests {
 	fun resolveNullableRequiredWithParameter() {
 		request.addParameter("name", "123")
 		var result = resolver.resolveArgument(nullableParamRequired, null, webRequest, binderFactory)
-		assertEquals("123", result)
+		assertThat(result).isEqualTo("123")
 	}
 
 	@Test
 	fun resolveNullableRequiredWithoutParameter() {
 		var result = resolver.resolveArgument(nullableParamRequired, null, webRequest, binderFactory)
-		assertNull(result)
+		assertThat(result).isNull()
 	}
 
 	@Test
 	fun resolveNullableNotRequiredWithParameter() {
 		request.addParameter("name", "123")
 		var result = resolver.resolveArgument(nullableParamNotRequired, null, webRequest, binderFactory)
-		assertEquals("123", result)
+		assertThat(result).isEqualTo("123")
 	}
 
 	@Test
 	fun resolveNullableNotRequiredWithoutParameter() {
 		var result = resolver.resolveArgument(nullableParamNotRequired, null, webRequest, binderFactory)
-		assertNull(result)
+		assertThat(result).isNull()
 	}
 
 	@Test
 	fun resolveNonNullableRequiredWithParameter() {
 		request.addParameter("name", "123")
 		var result = resolver.resolveArgument(nonNullableParamRequired, null, webRequest, binderFactory)
-		assertEquals("123", result)
+		assertThat(result).isEqualTo("123")
 	}
 
 	@Test
 	fun resolveNonNullableRequiredWithoutParameter() {
-		try {
+		assertThatExceptionOfType(MissingServletRequestParameterException::class.java).isThrownBy {
 			resolver.resolveArgument(nonNullableParamRequired, null, webRequest, binderFactory)
-			fail("should have thrown a MissingServletRequestParameterException")
-		}
-		catch (e: MissingServletRequestParameterException) {
-			// expected
 		}
 	}
 
@@ -138,17 +134,13 @@ class RequestParamMethodArgumentResolverKotlinTests {
 	fun resolveNonNullableNotRequiredWithParameter() {
 		request.addParameter("name", "123")
 		var result = resolver.resolveArgument(nonNullableParamNotRequired, null, webRequest, binderFactory)
-		assertEquals("123", result)
+		assertThat(result).isEqualTo("123")
 	}
 
 	@Test
 	fun resolveNonNullableNotRequiredWithoutParameter() {
-		try {
+		assertThatExceptionOfType(TypeCastException::class.java).isThrownBy {
 			resolver.resolveArgument(nonNullableParamNotRequired, null, webRequest, binderFactory) as String
-			fail("should have thrown a TypeCastException")
-		}
-		catch (e: TypeCastException) {
-			// expected
 		}
 	}
 
@@ -160,7 +152,7 @@ class RequestParamMethodArgumentResolverKotlinTests {
 		webRequest = ServletWebRequest(request)
 
 		var result = resolver.resolveArgument(nullableMultipartParamRequired, null, webRequest, binderFactory)
-		assertEquals(expected, result)
+		assertThat(result).isEqualTo(expected)
 	}
 
 	@Test
@@ -169,7 +161,7 @@ class RequestParamMethodArgumentResolverKotlinTests {
 		request.contentType = MediaType.MULTIPART_FORM_DATA_VALUE
 
 		var result = resolver.resolveArgument(nullableMultipartParamRequired, null, webRequest, binderFactory)
-		assertNull(result)
+		assertThat(result).isNull()
 	}
 
 	@Test
@@ -180,7 +172,7 @@ class RequestParamMethodArgumentResolverKotlinTests {
 		webRequest = ServletWebRequest(request)
 
 		var result = resolver.resolveArgument(nullableMultipartParamNotRequired, null, webRequest, binderFactory)
-		assertEquals(expected, result)
+		assertThat(result).isEqualTo(expected)
 	}
 
 	@Test
@@ -189,7 +181,7 @@ class RequestParamMethodArgumentResolverKotlinTests {
 		request.contentType = MediaType.MULTIPART_FORM_DATA_VALUE
 
 		var result = resolver.resolveArgument(nullableMultipartParamNotRequired, null, webRequest, binderFactory)
-		assertNull(result)
+		assertThat(result).isNull()
 	}
 
 	@Test
@@ -200,7 +192,7 @@ class RequestParamMethodArgumentResolverKotlinTests {
 		webRequest = ServletWebRequest(request)
 
 		var result = resolver.resolveArgument(nonNullableMultipartParamRequired, null, webRequest, binderFactory)
-		assertEquals(expected, result)
+		assertThat(result).isEqualTo(expected)
 	}
 
 	@Test
@@ -208,12 +200,8 @@ class RequestParamMethodArgumentResolverKotlinTests {
 		request.method = HttpMethod.POST.name
 		request.contentType = MediaType.MULTIPART_FORM_DATA_VALUE
 
-		try {
+		assertThatExceptionOfType(MissingServletRequestPartException::class.java).isThrownBy {
 			resolver.resolveArgument(nonNullableMultipartParamRequired, null, webRequest, binderFactory)
-			fail("should have thrown a MissingServletRequestPartException")
-		}
-		catch (e: MissingServletRequestPartException) {
-			// expected
 		}
 	}
 
@@ -225,7 +213,7 @@ class RequestParamMethodArgumentResolverKotlinTests {
 		webRequest = ServletWebRequest(request)
 
 		var result = resolver.resolveArgument(nonNullableMultipartParamNotRequired, null, webRequest, binderFactory)
-		assertEquals(expected, result)
+		assertThat(result).isEqualTo(expected)
 	}
 
 	@Test
@@ -233,12 +221,8 @@ class RequestParamMethodArgumentResolverKotlinTests {
 		request.method = HttpMethod.POST.name
 		request.contentType = MediaType.MULTIPART_FORM_DATA_VALUE
 
-		try {
+		assertThatExceptionOfType(TypeCastException::class.java).isThrownBy {
 			resolver.resolveArgument(nonNullableMultipartParamNotRequired, null, webRequest, binderFactory) as MultipartFile
-			fail("should have thrown a TypeCastException")
-		}
-		catch (e: TypeCastException) {
-			// expected
 		}
 	}
 

spring-webflux/src/test/kotlin/org/springframework/web/reactive/function/client/ClientResponseExtensionsTests.kt

@@ -21,8 +21,7 @@ import io.mockk.mockk
 import io.mockk.verify
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.runBlocking
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertNull
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.core.ParameterizedTypeReference
 import org.springframework.http.HttpStatus
@@ -74,7 +73,7 @@ class ClientResponseExtensionsTests {
 		val response = mockk<ClientResponse>()
 		every { response.bodyToMono<String>() } returns Mono.just("foo")
 		runBlocking {
-			assertEquals("foo", response.awaitBody<String>())
+			assertThat(response.awaitBody<String>()).isEqualTo("foo")
 		}
 	}
 
@@ -83,7 +82,7 @@ class ClientResponseExtensionsTests {
 		val response = mockk<ClientResponse>()
 		every { response.bodyToMono<String>() } returns Mono.empty()
 		runBlocking {
-			assertNull(response.awaitBodyOrNull<String>())
+			assertThat(response.awaitBodyOrNull<String>()).isNull()
 		}
 	}
 
@@ -93,7 +92,7 @@ class ClientResponseExtensionsTests {
 		val entity = ResponseEntity("foo", HttpStatus.OK)
 		every { response.toEntity<String>() } returns Mono.just(entity)
 		runBlocking {
-			assertEquals(entity, response.awaitEntity<String>())
+			assertThat(response.awaitEntity<String>()).isEqualTo(entity)
 		}
 	}
 
@@ -103,7 +102,7 @@ class ClientResponseExtensionsTests {
 		val entity = ResponseEntity(listOf("foo"), HttpStatus.OK)
 		every { response.toEntityList<String>() } returns Mono.just(entity)
 		runBlocking {
-			assertEquals(entity, response.awaitEntityList<String>())
+			assertThat(response.awaitEntityList<String>()).isEqualTo(entity)
 		}
 	}
 

spring-webflux/src/test/kotlin/org/springframework/web/reactive/function/client/WebClientExtensionsTests.kt

@@ -22,7 +22,7 @@ import io.mockk.verify
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.runBlocking
-import org.junit.jupiter.api.Assertions.assertEquals
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.reactivestreams.Publisher
 import org.springframework.core.ParameterizedTypeReference
@@ -86,7 +86,7 @@ class WebClientExtensionsTests {
 		val response = mockk<ClientResponse>()
 		every { requestBodySpec.exchange() } returns Mono.just(response)
 		runBlocking {
-			assertEquals(response, requestBodySpec.awaitExchange())
+			assertThat(requestBodySpec.awaitExchange()).isEqualTo(response)
 		}
 	}
 
@@ -95,7 +95,7 @@ class WebClientExtensionsTests {
 		val spec = mockk<WebClient.ResponseSpec>()
 		every { spec.bodyToMono<String>() } returns Mono.just("foo")
 		runBlocking {
-			assertEquals("foo", spec.awaitBody<String>())
+			assertThat(spec.awaitBody<String>()).isEqualTo("foo")
 		}
 	}
 

spring-webflux/src/test/kotlin/org/springframework/web/reactive/function/server/CoRouterFunctionDslTests.kt

@@ -16,8 +16,10 @@
 
 package org.springframework.web.reactive.function.server
 
-import org.junit.jupiter.api.fail
+import org.assertj.core.api.Assertions
+import org.assertj.core.api.Assertions.assertThatExceptionOfType
 import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.fail
 import org.springframework.core.io.ClassPathResource
 import org.springframework.http.HttpHeaders.*
 import org.springframework.http.HttpMethod.*
@@ -122,12 +124,8 @@ class CoRouterFunctionDslTests {
 
 	@Test
 	fun emptyRouter() {
-		try {
+		assertThatExceptionOfType(IllegalStateException::class.java).isThrownBy {
 			router { }
-			fail("should have thrown an IllegalStateException")
-		}
-		catch (e: IllegalStateException) {
-			// expected
 		}
 	}
 

spring-webflux/src/test/kotlin/org/springframework/web/reactive/function/server/RouterFunctionDslTests.kt

@@ -16,8 +16,10 @@
 
 package org.springframework.web.reactive.function.server
 
-import org.junit.jupiter.api.fail
+import org.assertj.core.api.Assertions
+import org.assertj.core.api.Assertions.assertThatExceptionOfType
 import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.fail
 import org.springframework.core.io.ClassPathResource
 import org.springframework.http.HttpHeaders.*
 import org.springframework.http.HttpMethod.*
@@ -123,12 +125,8 @@ class RouterFunctionDslTests {
 
 	@Test
 	fun emptyRouter() {
-		try {
+		assertThatExceptionOfType(IllegalStateException::class.java).isThrownBy {
 			router { }
-			fail("should have thrown an IllegalStateException")
-		}
-		catch (e: IllegalStateException) {
-			// expected
 		}
 	}
 

spring-webflux/src/test/kotlin/org/springframework/web/reactive/function/server/ServerRequestExtensionsTests.kt

@@ -21,8 +21,7 @@ import io.mockk.mockk
 import io.mockk.verify
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.runBlocking
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertNull
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.core.ParameterizedTypeReference
 import org.springframework.http.codec.multipart.Part
@@ -63,7 +62,7 @@ class ServerRequestExtensionsTests {
 	fun awaitBody() {
 		every { request.bodyToMono<String>() } returns Mono.just("foo")
 		runBlocking {
-			assertEquals("foo", request.awaitBody<String>())
+			assertThat(request.awaitBody<String>()).isEqualTo("foo")
 		}
 	}
 
@@ -71,7 +70,7 @@ class ServerRequestExtensionsTests {
 	fun awaitBodyOrNull() {
 		every { request.bodyToMono<String>() } returns Mono.empty()
 		runBlocking {
-			assertNull(request.awaitBodyOrNull<String>())
+			assertThat(request.awaitBodyOrNull<String>()).isNull()
 		}
 	}
 
@@ -80,7 +79,7 @@ class ServerRequestExtensionsTests {
 		val map = mockk<MultiValueMap<String, String>>()
 		every { request.formData() } returns Mono.just(map)
 		runBlocking {
-			assertEquals(map, request.awaitFormData())
+			assertThat(request.awaitFormData()).isEqualTo(map)
 		}
 	}
 
@@ -89,7 +88,7 @@ class ServerRequestExtensionsTests {
 		val map = mockk<MultiValueMap<String, Part>>()
 		every { request.multipartData() } returns Mono.just(map)
 		runBlocking {
-			assertEquals(map, request.awaitMultipartData())
+			assertThat(request.awaitMultipartData()).isEqualTo(map)
 		}
 	}
 
@@ -98,7 +97,7 @@ class ServerRequestExtensionsTests {
 		val principal = mockk<Principal>()
 		every { request.principal() } returns Mono.just(principal)
 		runBlocking {
-			assertEquals(principal, request.awaitPrincipal())
+			assertThat(request.awaitPrincipal()).isEqualTo(principal)
 		}
 	}
 
@@ -107,7 +106,7 @@ class ServerRequestExtensionsTests {
 		val session = mockk<WebSession>()
 		every { request.session() } returns Mono.just(session)
 		runBlocking {
-			assertEquals(session, request.awaitSession())
+			assertThat(request.awaitSession()).isEqualTo(session)
 		}
 	}
 

spring-webflux/src/test/kotlin/org/springframework/web/reactive/function/server/ServerResponseExtensionsTests.kt

@@ -23,7 +23,7 @@ import io.reactivex.Flowable
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.runBlocking
-import org.junit.jupiter.api.Assertions.assertEquals
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.reactivestreams.Publisher
 import org.springframework.core.ParameterizedTypeReference
@@ -145,7 +145,7 @@ class ServerResponseExtensionsTests {
 		val builder = mockk<ServerResponse.HeadersBuilder<*>>()
 		every { builder.build() } returns Mono.just(response)
 		runBlocking {
-			assertEquals(response, builder.buildAndAwait())
+			assertThat(builder.buildAndAwait()).isEqualTo(response)
 		}
 	}
 

spring-webflux/src/test/kotlin/org/springframework/web/reactive/result/KotlinInvocableHandlerMethodTests.kt

@@ -19,9 +19,7 @@ package org.springframework.web.reactive.result
 import io.mockk.every
 import io.mockk.mockk
 import kotlinx.coroutines.delay
-import org.hamcrest.CoreMatchers.`is`
-import org.hamcrest.MatcherAssert.assertThat
-import org.junit.jupiter.api.Assertions.assertEquals
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.http.HttpStatus
 import org.springframework.http.server.reactive.ServerHttpResponse
@@ -83,7 +81,7 @@ class KotlinInvocableHandlerMethodTests {
 		val result = invoke(CoroutinesController(), method)
 
 		assertHandlerResultValue(result, "created")
-		assertThat<HttpStatus>(this.exchange.response.statusCode, `is`(HttpStatus.CREATED))
+		assertThat(this.exchange.response.statusCode).isSameAs(HttpStatus.CREATED)
 	}
 
 	@Test
@@ -96,7 +94,7 @@ class KotlinInvocableHandlerMethodTests {
 		StepVerifier.create(result)
 				.consumeNextWith { StepVerifier.create(it.returnValue as Mono<*>).verifyComplete() }
 				.verifyComplete()
-		assertEquals("bar", this.exchange.response.headers.getFirst("foo"))
+		assertThat(this.exchange.response.headers.getFirst("foo")).isEqualTo("bar")
 	}
 
 	private fun invoke(handler: Any, method: Method, vararg providedArgs: Any?): Mono<HandlerResult> {

spring-webflux/src/test/kotlin/org/springframework/web/reactive/result/method/annotation/CoroutinesIntegrationTests.kt

@@ -17,14 +17,12 @@
 package org.springframework.web.reactive.result.method.annotation
 
 import kotlinx.coroutines.Deferred
-import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.async
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.flow
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.fail
+import org.assertj.core.api.Assertions.*
 import org.springframework.context.ApplicationContext
 import org.springframework.context.annotation.AnnotationConfigApplicationContext
 import org.springframework.context.annotation.ComponentScan
@@ -37,7 +35,6 @@ import org.springframework.web.bind.annotation.RestController
 import org.springframework.web.client.HttpServerErrorException
 import org.springframework.web.reactive.config.EnableWebFlux
 
-@ExperimentalCoroutinesApi
 class CoroutinesIntegrationTests : AbstractRequestMappingIntegrationTests() {
 
 	override fun initApplicationContext(): ApplicationContext {
@@ -53,8 +50,8 @@ class CoroutinesIntegrationTests : AbstractRequestMappingIntegrationTests() {
 		startServer(httpServer)
 
 		val entity = performGet<String>("/suspend", HttpHeaders.EMPTY, String::class.java)
-		assertEquals(HttpStatus.OK, entity.statusCode)
-		assertEquals("foo", entity.body)
+		assertThat(entity.statusCode).isEqualTo(HttpStatus.OK)
+		assertThat(entity.body).isEqualTo("foo")
 	}
 
 	@ParameterizedHttpServerTest
@@ -62,8 +59,8 @@ class CoroutinesIntegrationTests : AbstractRequestMappingIntegrationTests() {
 		startServer(httpServer)
 
 		val entity = performGet<String>("/deferred", HttpHeaders.EMPTY, String::class.java)
-		assertEquals(HttpStatus.OK, entity.statusCode)
-		assertEquals("foo", entity.body)
+		assertThat(entity.statusCode).isEqualTo(HttpStatus.OK)
+		assertThat(entity.body).isEqualTo("foo")
 	}
 
 	@ParameterizedHttpServerTest
@@ -71,8 +68,8 @@ class CoroutinesIntegrationTests : AbstractRequestMappingIntegrationTests() {
 		startServer(httpServer)
 
 		val entity = performGet<String>("/flow", HttpHeaders.EMPTY, String::class.java)
-		assertEquals(HttpStatus.OK, entity.statusCode)
-		assertEquals("foobar", entity.body)
+		assertThat(entity.statusCode).isEqualTo(HttpStatus.OK)
+		assertThat(entity.body).isEqualTo("foobar")
 	}
 
 	@ParameterizedHttpServerTest
@@ -80,19 +77,16 @@ class CoroutinesIntegrationTests : AbstractRequestMappingIntegrationTests() {
 		startServer(httpServer)
 
 		val entity = performGet<String>("/suspending-flow", HttpHeaders.EMPTY, String::class.java)
-		assertEquals(HttpStatus.OK, entity.statusCode)
-		assertEquals("foobar", entity.body)
+		assertThat(entity.statusCode).isEqualTo(HttpStatus.OK)
+		assertThat(entity.body).isEqualTo("foobar")
 	}
 
 	@ParameterizedHttpServerTest
 	fun `Suspending handler method throwing exception`(httpServer: HttpServer) {
 		startServer(httpServer)
 
-		try {
+		assertThatExceptionOfType(HttpServerErrorException.InternalServerError::class.java).isThrownBy {
 			performGet<String>("/error", HttpHeaders.EMPTY, String::class.java)
-			fail("should have thrown an HttpServerErrorException.InternalServerError")
-		} catch (e: HttpServerErrorException.InternalServerError) {
-			// expected
 		}
 	}
 
@@ -100,11 +94,8 @@ class CoroutinesIntegrationTests : AbstractRequestMappingIntegrationTests() {
 	fun `Handler method returning Flow throwing exception`(httpServer: HttpServer) {
 		startServer(httpServer)
 
-		try {
+		assertThatExceptionOfType(HttpServerErrorException.InternalServerError::class.java).isThrownBy {
 			performGet<String>("/flow-error", HttpHeaders.EMPTY, String::class.java)
-			fail("should have thrown an HttpServerErrorException.InternalServerError")
-		} catch (e: HttpServerErrorException.InternalServerError) {
-			// expected
 		}
 	}
 

spring-webmvc/src/test/kotlin/org/springframework/web/servlet/function/RouterFunctionDslTests.kt

@@ -16,9 +16,7 @@
 
 package org.springframework.web.servlet.function
 
-import org.junit.jupiter.api.Assertions.assertFalse
-import org.junit.jupiter.api.Assertions.assertTrue
-import org.junit.jupiter.api.fail
+import org.assertj.core.api.Assertions.*
 import org.junit.jupiter.api.Test
 import org.springframework.core.io.ClassPathResource
 import org.springframework.http.HttpHeaders.*
@@ -38,7 +36,7 @@ class RouterFunctionDslTests {
 		val servletRequest = MockHttpServletRequest()
 		servletRequest.addHeader("bar", "bar")
 		val request = DefaultServerRequest(servletRequest, emptyList())
-		assertTrue(sampleRouter().route(request).isPresent)
+		assertThat(sampleRouter().route(request).isPresent).isTrue()
 	}
 
 	@Test
@@ -46,7 +44,7 @@ class RouterFunctionDslTests {
 		val servletRequest = MockHttpServletRequest("GET", "/content")
 		servletRequest.addHeader(ACCEPT, APPLICATION_ATOM_XML_VALUE)
 		val request = DefaultServerRequest(servletRequest, emptyList())
-		assertTrue(sampleRouter().route(request).isPresent)
+		assertThat(sampleRouter().route(request).isPresent).isTrue()
 	}
 
 	@Test
@@ -54,7 +52,7 @@ class RouterFunctionDslTests {
 		val servletRequest = MockHttpServletRequest("POST", "/api/foo/")
 		servletRequest.addHeader(ACCEPT, APPLICATION_JSON_VALUE)
 		val request = DefaultServerRequest(servletRequest, emptyList())
-		assertTrue(sampleRouter().route(request).isPresent)
+		assertThat(sampleRouter().route(request).isPresent).isTrue()
 	}
 
 	@Test
@@ -62,35 +60,35 @@ class RouterFunctionDslTests {
 		val servletRequest = MockHttpServletRequest("GET", "/content")
 		servletRequest.addHeader(CONTENT_TYPE, APPLICATION_OCTET_STREAM_VALUE)
 		val request = DefaultServerRequest(servletRequest, emptyList())
-		assertTrue(sampleRouter().route(request).isPresent)
+		assertThat(sampleRouter().route(request).isPresent).isTrue()
 	}
 
 	@Test
 	fun resourceByPath() {
 		val servletRequest = MockHttpServletRequest("GET", "/org/springframework/web/servlet/function/response.txt")
 		val request = DefaultServerRequest(servletRequest, emptyList())
-		assertTrue(sampleRouter().route(request).isPresent)
+		assertThat(sampleRouter().route(request).isPresent).isTrue()
 	}
 
 	@Test
 	fun method() {
 		val servletRequest = MockHttpServletRequest("PATCH", "/")
 		val request = DefaultServerRequest(servletRequest, emptyList())
-		assertTrue(sampleRouter().route(request).isPresent)
+		assertThat(sampleRouter().route(request).isPresent).isTrue()
 	}
 
 	@Test
 	fun path() {
 		val servletRequest = MockHttpServletRequest("GET", "/baz")
 		val request = DefaultServerRequest(servletRequest, emptyList())
-		assertTrue(sampleRouter().route(request).isPresent)
+		assertThat(sampleRouter().route(request).isPresent).isTrue()
 	}
 
 	@Test
 	fun resource() {
 		val servletRequest = MockHttpServletRequest("GET", "/response.txt")
 		val request = DefaultServerRequest(servletRequest, emptyList())
-		assertTrue(sampleRouter().route(request).isPresent)
+		assertThat(sampleRouter().route(request).isPresent).isTrue()
 	}
 
 	@Test
@@ -100,24 +98,20 @@ class RouterFunctionDslTests {
 		servletRequest.addHeader(ACCEPT, APPLICATION_PDF_VALUE)
 		servletRequest.addHeader(CONTENT_TYPE, APPLICATION_PDF_VALUE)
 		val request = DefaultServerRequest(servletRequest, emptyList())
-		assertFalse(sampleRouter().route(request).isPresent)
+		assertThat(sampleRouter().route(request).isPresent).isFalse()
 	}
 
 	@Test
 	fun rendering() {
 		val servletRequest = MockHttpServletRequest("GET", "/rendering")
 		val request = DefaultServerRequest(servletRequest, emptyList())
-		assertTrue(sampleRouter().route(request).get().handle(request) is RenderingResponse)
+		assertThat(sampleRouter().route(request).get().handle(request) is RenderingResponse).isTrue()
 	}
 
 	@Test
 	fun emptyRouter() {
-		try {
+		assertThatExceptionOfType(IllegalStateException::class.java).isThrownBy {
 			router { }
-			fail("should have thrown an IllegalStateException")
-		}
-		catch (e: IllegalStateException) {
-			// expected
 		}
 	}
 

spring-webmvc/src/test/kotlin/org/springframework/web/servlet/function/ServerRequestExtensionsTests.kt

@@ -19,8 +19,7 @@ package org.springframework.web.servlet.function
 import io.mockk.every
 import io.mockk.mockk
 import io.mockk.verify
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertNull
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.core.ParameterizedTypeReference
 import org.springframework.http.MediaType
@@ -43,23 +42,23 @@ class ServerRequestExtensionsTests {
 	fun `remoteAddressOrNull with value`() {
 		val remoteAddress = mockk<InetSocketAddress>()
 		every { request.remoteAddress() } returns Optional.of(remoteAddress)
-		assertEquals(remoteAddress, request.remoteAddressOrNull())
+		assertThat(remoteAddress).isEqualTo(request.remoteAddressOrNull())
 		verify { request.remoteAddress() }
 	}
 
 	@Test
 	fun `remoteAddressOrNull with null`() {
 		every { request.remoteAddress() } returns Optional.empty()
-		assertNull(request.remoteAddressOrNull())
+		assertThat(request.remoteAddressOrNull()).isNull()
 		verify { request.remoteAddress() }
 	}
 
 	@Test
 	fun body() {
-		val body = Arrays.asList("foo", "bar")
+		val body = listOf("foo", "bar")
 		val typeReference = object: ParameterizedTypeReference<List<String>>() {}
 		every { request.body(typeReference) } returns body
-		assertEquals(body, request.body<List<String>>())
+		assertThat(request.body<List<String>>()).isEqualTo(body)
 		verify { request.body(typeReference) }
 	}
 
@@ -67,14 +66,14 @@ class ServerRequestExtensionsTests {
 	fun `attributeOrNull with value`() {
 		val attribute = mockk<Any>()
 		every { request.attribute("foo") } returns Optional.of(attribute)
-		assertEquals(attribute, request.attributeOrNull("foo"))
+		assertThat(request.attributeOrNull("foo")).isEqualTo(attribute)
 		verify { request.attribute("foo") }
 	}
 
 	@Test
 	fun `attributeOrNull with null`() {
 		every { request.attribute("foo") } returns Optional.empty()
-		assertNull(request.attributeOrNull("foo"))
+		assertThat(request.attributeOrNull("foo")).isNull()
 		verify { request.attribute("foo") }
 	}
 
@@ -82,14 +81,14 @@ class ServerRequestExtensionsTests {
 	fun `paramOrNull with value`() {
 		val param = "bar"
 		every { request.param("foo") } returns Optional.of(param)
-		assertEquals(param, request.paramOrNull("foo"))
+		assertThat(request.paramOrNull("foo")).isEqualTo(param)
 		verify { request.param("foo") }
 	}
 
 	@Test
 	fun `paramOrNull with null`() {
 		every { request.param("foo") } returns Optional.empty()
-		assertNull(request.paramOrNull("foo"))
+		assertThat(request.paramOrNull("foo")).isNull()
 		verify { request.param("foo") }
 	}
 
@@ -97,14 +96,14 @@ class ServerRequestExtensionsTests {
 	fun `principalOrNull with value`() {
 		val principal = mockk<Principal>()
 		every { request.principal() } returns Optional.of(principal)
-		assertEquals(principal, request.principalOrNull())
+		assertThat(request.principalOrNull()).isEqualTo(principal)
 		verify { request.principal() }
 	}
 
 	@Test
 	fun `principalOrNull with null`() {
 		every { request.principal() } returns Optional.empty()
-		assertNull(request.principalOrNull())
+		assertThat(request.principalOrNull()).isNull()
 		verify { request.principal() }
 	}
 
@@ -112,14 +111,14 @@ class ServerRequestExtensionsTests {
 	fun `contentLengthOrNull with value`() {
 		val contentLength: Long = 123
 		every { headers.contentLength() } returns OptionalLong.of(contentLength)
-		assertEquals(contentLength, headers.contentLengthOrNull())
+		assertThat(headers.contentLengthOrNull()).isEqualTo(contentLength)
 		verify { headers.contentLength() }
 	}
 
 	@Test
 	fun `contentLengthOrNull with null`() {
 		every { headers.contentLength() } returns OptionalLong.empty()
-		assertNull(headers.contentLengthOrNull())
+		assertThat(headers.contentLengthOrNull()).isNull()
 		verify { headers.contentLength() }
 	}
 
@@ -127,14 +126,14 @@ class ServerRequestExtensionsTests {
 	fun `contentTypeOrNull with value`() {
 		val contentType = mockk<MediaType>()
 		every { headers.contentType() } returns Optional.of(contentType)
-		assertEquals(contentType, headers.contentTypeOrNull())
+		assertThat(headers.contentTypeOrNull()).isEqualTo(contentType)
 		verify { headers.contentType() }
 	}
 
 	@Test
 	fun `contentTypeOrNull with null`() {
 		every { headers.contentType() } returns Optional.empty()
-		assertNull(headers.contentTypeOrNull())
+		assertThat(headers.contentTypeOrNull()).isNull()
 		verify { headers.contentType() }
 	}
 }

spring-webmvc/src/test/kotlin/org/springframework/web/servlet/function/ServerResponseExtensionsTests.kt

@@ -19,10 +19,9 @@ package org.springframework.web.servlet.function
 import io.mockk.every
 import io.mockk.mockk
 import io.mockk.verify
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.core.ParameterizedTypeReference
-import java.util.*
-import org.junit.jupiter.api.Assertions.assertEquals
 
 /**
  * Tests for WebMvc.fn [ServerResponse] extensions.
@@ -35,10 +34,10 @@ class ServerResponseExtensionsTests {
 	fun bodyWithType() {
 		val builder = mockk<ServerResponse.BodyBuilder>()
 		val response = mockk<ServerResponse>()
-		val body = Arrays.asList("foo", "bar")
+		val body = listOf("foo", "bar")
 		val typeReference = object: ParameterizedTypeReference<List<String>>() {}
 		every { builder.body(body, typeReference) } returns response
-		assertEquals(response, builder.bodyWithType<List<String>>(body))
+		assertThat(builder.bodyWithType<List<String>>(body)).isEqualTo(response)
 		verify { builder.body(body, typeReference) }
 	}
 }

spring-webmvc/src/test/kotlin/org/springframework/web/servlet/mvc/method/annotation/ServletAnnotationControllerHandlerMethodKotlinTests.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,7 @@
 
 package org.springframework.web.servlet.mvc.method.annotation
 
-import org.junit.jupiter.api.Assertions.*
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.mock.web.test.MockHttpServletRequest
 import org.springframework.mock.web.test.MockHttpServletResponse
@@ -37,7 +37,7 @@ class ServletAnnotationControllerHandlerMethodKotlinTests : AbstractServletHandl
 		request.addParameter("param2", "2")
 		val response = MockHttpServletResponse()
 		servlet.service(request, response)
-		assertEquals("value1-2", response.contentAsString)
+		assertThat(response.contentAsString).isEqualTo("value1-2")
 	}
 
 	@Test
@@ -49,7 +49,7 @@ class ServletAnnotationControllerHandlerMethodKotlinTests : AbstractServletHandl
 		request.addParameter("param2", "2")
 		val response = MockHttpServletResponse()
 		servlet.service(request, response)
-		assertEquals("value1-2", response.contentAsString)
+		assertThat(response.contentAsString).isEqualTo("value1-2")
 	}
 
 	@Test
@@ -60,7 +60,7 @@ class ServletAnnotationControllerHandlerMethodKotlinTests : AbstractServletHandl
 		request.addParameter("param1", "value1")
 		val response = MockHttpServletResponse()
 		servlet.service(request, response)
-		assertEquals("value1-12", response.contentAsString)
+		assertThat(response.contentAsString).isEqualTo("value1-12")
 	}