Enforces static imports for JUnit 4 assertions and assumptions

This commit configures Checkstyle to enforces static imports for JUnit 4
assertions and assumptions.

See gh-22932

spring-aspects/src/test/java/org/springframework/cache/aspectj/AspectJCacheAnnotationTests.java

@@ -16,7 +16,6 @@
 
 package org.springframework.cache.aspectj;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import org.springframework.cache.Cache;
@@ -44,7 +43,7 @@ public class AspectJCacheAnnotationTests extends AbstractCacheAnnotationTests {
 	public void testKeyStrategy() throws Exception {
 		AnnotationCacheAspect aspect = ctx.getBean(
 				"org.springframework.cache.config.internalCacheAspect", AnnotationCacheAspect.class);
-		Assert.assertSame(ctx.getBean("keyGenerator"), aspect.getKeyGenerator());
+		assertSame(ctx.getBean("keyGenerator"), aspect.getKeyGenerator());
 	}
 
 	@Override

spring-context/src/test/java/org/springframework/cache/config/CacheAdviceNamespaceTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 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.
@@ -16,13 +16,14 @@
 
 package org.springframework.cache.config;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import org.springframework.cache.interceptor.CacheInterceptor;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.support.GenericXmlApplicationContext;
 
+import static org.junit.Assert.assertSame;
+
 /**
  * @author Costin Leau
  * @author Chris Beams
@@ -38,7 +39,7 @@ public class CacheAdviceNamespaceTests extends AbstractCacheAnnotationTests {
 	@Test
 	public void testKeyStrategy() throws Exception {
 		CacheInterceptor bean = this.ctx.getBean("cacheAdviceClass", CacheInterceptor.class);
-		Assert.assertSame(this.ctx.getBean("keyGenerator"), bean.getKeyGenerator());
+		assertSame(this.ctx.getBean("keyGenerator"), bean.getKeyGenerator());
 	}
 
 }

spring-jdbc/src/test/java/org/springframework/jdbc/core/simple/SimpleJdbcCallTests.java

@@ -24,7 +24,6 @@ import java.sql.SQLException;
 import java.sql.Types;
 import javax.sql.DataSource;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -232,7 +231,7 @@ public class SimpleJdbcCallTests {
 
 
 	private void verifyStatement(SimpleJdbcCall adder, String expected) {
-		Assert.assertEquals("Incorrect call statement", expected, adder.getCallString());
+		assertEquals("Incorrect call statement", expected, adder.getCallString());
 	}
 
 	private void initializeAddInvoiceWithoutMetaData(boolean isFunction) throws SQLException {

spring-oxm/src/test/java/org/springframework/oxm/jibx/JibxMarshallerTests.java

@@ -19,7 +19,6 @@ package org.springframework.oxm.jibx;
 import java.io.StringWriter;
 import javax.xml.transform.stream.StreamResult;
 
-import org.junit.Assume;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -28,6 +27,7 @@ import org.springframework.oxm.AbstractMarshallerTests;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeTrue;
 import static org.xmlunit.matchers.CompareMatcher.isSimilarTo;
 
 /**
@@ -43,7 +43,7 @@ public class JibxMarshallerTests extends AbstractMarshallerTests<JibxMarshaller>
 	@BeforeClass
 	public static void compilerAssumptions() {
 		// JiBX compiler is currently not compatible with JDK 9
-		Assume.assumeTrue(System.getProperty("java.version").startsWith("1.8."));
+		assumeTrue(System.getProperty("java.version").startsWith("1.8."));
 	}
 
 

spring-oxm/src/test/java/org/springframework/oxm/jibx/JibxUnmarshallerTests.java

@@ -19,7 +19,6 @@ package org.springframework.oxm.jibx;
 import java.io.ByteArrayInputStream;
 import javax.xml.transform.stream.StreamSource;
 
-import org.junit.Assume;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -27,6 +26,7 @@ import org.springframework.oxm.AbstractUnmarshallerTests;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assume.assumeTrue;
 
 /**
  * NOTE: These tests fail under Eclipse/IDEA because JiBX binding does
@@ -46,7 +46,7 @@ public class JibxUnmarshallerTests extends AbstractUnmarshallerTests<JibxMarshal
 	@BeforeClass
 	public static void compilerAssumptions() {
 		// JiBX compiler is currently not compatible with JDK 9
-		Assume.assumeTrue(System.getProperty("java.version").startsWith("1.8."));
+		assumeTrue(System.getProperty("java.version").startsWith("1.8."));
 	}
 
 

spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/MultipartControllerTests.java

@@ -30,7 +30,6 @@ import javax.servlet.http.HttpServletRequestWrapper;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.Part;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import org.springframework.http.MediaType;
@@ -46,6 +45,7 @@ import org.springframework.web.bind.annotation.RequestPart;
 import org.springframework.web.filter.OncePerRequestFilter;
 import org.springframework.web.multipart.MultipartFile;
 
+import static org.junit.Assert.assertArrayEquals;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.multipart;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.model;
@@ -275,7 +275,7 @@ public class MultipartControllerTests {
 
 			if (file != null && file.length > 0) {
 				byte[] content = file[0].getBytes();
-				Assert.assertArrayEquals(content, file[1].getBytes());
+				assertArrayEquals(content, file[1].getBytes());
 				model.addAttribute("fileContent", content);
 			}
 			if (json != null) {
@@ -291,7 +291,7 @@ public class MultipartControllerTests {
 
 			if (file != null && !file.isEmpty()) {
 				byte[] content = file.get(0).getBytes();
-				Assert.assertArrayEquals(content, file.get(1).getBytes());
+				assertArrayEquals(content, file.get(1).getBytes());
 				model.addAttribute("fileContent", content);
 			}
 			if (json != null) {
@@ -319,7 +319,7 @@ public class MultipartControllerTests {
 
 			if (file.isPresent()) {
 				byte[] content = file.get()[0].getBytes();
-				Assert.assertArrayEquals(content, file.get()[1].getBytes());
+				assertArrayEquals(content, file.get()[1].getBytes());
 				model.addAttribute("fileContent", content);
 			}
 			model.addAttribute("jsonContent", json);
@@ -333,7 +333,7 @@ public class MultipartControllerTests {
 
 			if (file.isPresent()) {
 				byte[] content = file.get().get(0).getBytes();
-				Assert.assertArrayEquals(content, file.get().get(1).getBytes());
+				assertArrayEquals(content, file.get().get(1).getBytes());
 				model.addAttribute("fileContent", content);
 			}
 			model.addAttribute("jsonContent", json);

spring-web/src/test/java/org/springframework/web/client/AsyncRestTemplateIntegrationTests.java

@@ -27,7 +27,6 @@ import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import org.springframework.core.io.ClassPathResource;
@@ -315,7 +314,7 @@ public class AsyncRestTemplateIntegrationTests extends AbstractMockWebServerTest
 	@Test
 	public void deleteCallbackWithLambdas() throws Exception  {
 		ListenableFuture<?> deletedFuture = template.delete(new URI(baseUrl + "/delete"));
-		deletedFuture.addCallback(Assert::assertNull, ex -> fail(ex.getMessage()));
+		deletedFuture.addCallback(result -> assertNull(result), ex -> fail(ex.getMessage()));
 		waitTillDone(deletedFuture);
 	}
 

spring-webflux/src/test/java/org/springframework/web/reactive/function/BodyExtractorsTests.java

@@ -29,7 +29,6 @@ import java.util.Optional;
 import com.fasterxml.jackson.annotation.JsonView;
 import io.netty.buffer.PooledByteBufAllocator;
 import io.netty.util.IllegalReferenceCountException;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import reactor.core.publisher.Flux;
@@ -67,6 +66,7 @@ import org.springframework.util.MultiValueMap;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 import static org.springframework.http.codec.json.Jackson2CodecSupport.JSON_VIEW_HINT;
 
 /**
@@ -436,7 +436,7 @@ public class BodyExtractorsTests {
 					assertTrue(throwable instanceof UnsupportedMediaTypeException);
 					try {
 						buffer.release();
-						Assert.fail("releasing the buffer should have failed");
+						fail("releasing the buffer should have failed");
 					}
 					catch (IllegalReferenceCountException exc) {
 					}

spring-webflux/src/test/java/org/springframework/web/reactive/function/BodyInsertersTests.java

@@ -30,7 +30,6 @@ import java.util.Map;
 import java.util.Optional;
 
 import com.fasterxml.jackson.annotation.JsonView;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import reactor.core.publisher.Flux;
@@ -71,6 +70,7 @@ import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.containsString;
 import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
 import static org.springframework.http.codec.json.Jackson2CodecSupport.JSON_VIEW_HINT;
 
 /**
@@ -127,7 +127,7 @@ public class BodyInsertersTests {
 		StepVerifier.create(response.getBody())
 				.consumeNextWith(buf -> {
 					String actual = DataBufferTestUtils.dumpString(buf, UTF_8);
-					Assert.assertEquals("foo", actual);
+					assertEquals("foo", actual);
 				})
 				.expectComplete()
 				.verify();
@@ -173,7 +173,7 @@ public class BodyInsertersTests {
 		StepVerifier.create(response.getBody())
 				.consumeNextWith(buf -> {
 					String actual = DataBufferTestUtils.dumpString(buf, UTF_8);
-					Assert.assertEquals("foo", actual);
+					assertEquals("foo", actual);
 				})
 				.expectComplete()
 				.verify();

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ProtobufIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 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.
@@ -18,7 +18,6 @@ package org.springframework.web.reactive.result.method.annotation;
 
 import java.time.Duration;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import reactor.core.publisher.Flux;
@@ -36,6 +35,9 @@ import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.reactive.protobuf.Msg;
 import org.springframework.web.reactive.protobuf.SecondMsg;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+
 /**
  * Integration tests for Protobuf support.
  *
@@ -71,9 +73,9 @@ public class ProtobufIntegrationTests extends AbstractRequestMappingIntegrationT
 				.uri("/message")
 				.exchange()
 				.doOnNext(response -> {
-					Assert.assertFalse(response.headers().contentType().get().getParameters().containsKey("delimited"));
-					Assert.assertEquals("sample.proto", response.headers().header("X-Protobuf-Schema").get(0));
-					Assert.assertEquals("Msg", response.headers().header("X-Protobuf-Message").get(0));
+					assertFalse(response.headers().contentType().get().getParameters().containsKey("delimited"));
+					assertEquals("sample.proto", response.headers().header("X-Protobuf-Schema").get(0));
+					assertEquals("Msg", response.headers().header("X-Protobuf-Message").get(0));
 				})
 				.flatMap(response -> response.bodyToMono(Msg.class));
 
@@ -88,9 +90,9 @@ public class ProtobufIntegrationTests extends AbstractRequestMappingIntegrationT
 				.uri("/messages")
 				.exchange()
 				.doOnNext(response -> {
-					Assert.assertEquals("true", response.headers().contentType().get().getParameters().get("delimited"));
-					Assert.assertEquals("sample.proto", response.headers().header("X-Protobuf-Schema").get(0));
-					Assert.assertEquals("Msg", response.headers().header("X-Protobuf-Message").get(0));
+					assertEquals("true", response.headers().contentType().get().getParameters().get("delimited"));
+					assertEquals("sample.proto", response.headers().header("X-Protobuf-Schema").get(0));
+					assertEquals("Msg", response.headers().header("X-Protobuf-Message").get(0));
 				})
 				.flatMapMany(response -> response.bodyToFlux(Msg.class));
 
@@ -107,9 +109,9 @@ public class ProtobufIntegrationTests extends AbstractRequestMappingIntegrationT
 				.uri("/message-stream")
 				.exchange()
 				.doOnNext(response -> {
-					Assert.assertEquals("true", response.headers().contentType().get().getParameters().get("delimited"));
-					Assert.assertEquals("sample.proto", response.headers().header("X-Protobuf-Schema").get(0));
-					Assert.assertEquals("Msg", response.headers().header("X-Protobuf-Message").get(0));
+					assertEquals("true", response.headers().contentType().get().getParameters().get("delimited"));
+					assertEquals("sample.proto", response.headers().header("X-Protobuf-Schema").get(0));
+					assertEquals("Msg", response.headers().header("X-Protobuf-Message").get(0));
 				})
 				.flatMapMany(response -> response.bodyToFlux(Msg.class));
 

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/SseIntegrationTests.java

@@ -19,7 +19,6 @@ package org.springframework.web.reactive.result.method.annotation;
 import java.io.File;
 import java.time.Duration;
 
-import org.junit.Assume;
 import org.junit.Before;
 import org.junit.Ignore;
 import org.junit.Test;
@@ -136,7 +135,7 @@ public class SseIntegrationTests extends AbstractHttpHandlerIntegrationTests {
 	@Test
 	public void sseAsEvent() {
 
-		Assume.assumeTrue(server instanceof JettyHttpServer);
+		assumeTrue(server instanceof JettyHttpServer);
 
 		Flux<ServerSentEvent<Person>> result = this.webClient.get()
 				.uri("/event")

spring-webflux/src/test/java/org/springframework/web/reactive/result/view/script/ScriptTemplateViewResolverTests.java

@@ -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.
@@ -16,11 +16,12 @@
 
 package org.springframework.web.reactive.result.view.script;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import org.springframework.beans.DirectFieldAccessor;
 
+import static org.junit.Assert.assertEquals;
+
 /**
  * Unit tests for {@link ScriptTemplateViewResolver}.
  *
@@ -31,10 +32,10 @@ public class ScriptTemplateViewResolverTests {
 	@Test
 	public void viewClass() throws Exception {
 		ScriptTemplateViewResolver resolver = new ScriptTemplateViewResolver();
-		Assert.assertEquals(ScriptTemplateView.class, resolver.requiredViewClass());
+		assertEquals(ScriptTemplateView.class, resolver.requiredViewClass());
 		DirectFieldAccessor viewAccessor = new DirectFieldAccessor(resolver);
 		Class<?> viewClass = (Class<?>) viewAccessor.getPropertyValue("viewClass");
-		Assert.assertEquals(ScriptTemplateView.class, viewClass);
+		assertEquals(ScriptTemplateView.class, viewClass);
 	}
 
 }

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/RequestPartIntegrationTests.java

@@ -31,7 +31,6 @@ import org.eclipse.jetty.server.Server;
 import org.eclipse.jetty.servlet.ServletContextHandler;
 import org.eclipse.jetty.servlet.ServletHolder;
 import org.junit.AfterClass;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
@@ -67,6 +66,7 @@ import org.springframework.web.servlet.DispatcherServlet;
 import org.springframework.web.servlet.config.annotation.EnableWebMvc;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
 
+import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.springframework.web.bind.annotation.RequestMethod.POST;
 
@@ -239,7 +239,7 @@ public class RequestPartIntegrationTests {
 				@RequestPart(name = "empty-data", required = false) TestData emptyData,
 				@RequestPart(name = "iso-8859-1-data") byte[] iso88591Data) {
 
-			Assert.assertArrayEquals(new byte[]{(byte) 0xC4}, iso88591Data);
+			assertArrayEquals(new byte[]{(byte) 0xC4}, iso88591Data);
 
 			String url = "http://localhost:8080/test/" + testData.getName() + "/" + file.get().getOriginalFilename();
 			HttpHeaders headers = new HttpHeaders();

spring-webmvc/src/test/java/org/springframework/web/servlet/view/groovy/GroovyMarkupViewResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 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.
@@ -18,11 +18,13 @@ package org.springframework.web.servlet.view.groovy;
 
 import java.util.Locale;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import org.springframework.beans.DirectFieldAccessor;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
 /**
  * Unit tests for
  * {@link org.springframework.web.servlet.view.groovy.GroovyMarkupViewResolver}.
@@ -34,18 +36,18 @@ public class GroovyMarkupViewResolverTests {
 	@Test
 	public void viewClass() throws Exception {
 		GroovyMarkupViewResolver resolver = new GroovyMarkupViewResolver();
-		Assert.assertEquals(GroovyMarkupView.class, resolver.requiredViewClass());
+		assertEquals(GroovyMarkupView.class, resolver.requiredViewClass());
 		DirectFieldAccessor viewAccessor = new DirectFieldAccessor(resolver);
 		Class<?> viewClass = (Class<?>) viewAccessor.getPropertyValue("viewClass");
-		Assert.assertEquals(GroovyMarkupView.class, viewClass);
+		assertEquals(GroovyMarkupView.class, viewClass);
 	}
 
 	@Test
 	public void cacheKey() throws Exception {
 		GroovyMarkupViewResolver resolver = new GroovyMarkupViewResolver();
 		String cacheKey = (String) resolver.getCacheKey("test", Locale.US);
-		Assert.assertNotNull(cacheKey);
-		Assert.assertEquals("test_en_US", cacheKey);
+		assertNotNull(cacheKey);
+		assertEquals("test_en_US", cacheKey);
 	}
 
 }

spring-webmvc/src/test/java/org/springframework/web/servlet/view/script/ScriptTemplateViewResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 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.
@@ -16,11 +16,12 @@
 
 package org.springframework.web.servlet.view.script;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import org.springframework.beans.DirectFieldAccessor;
 
+import static org.junit.Assert.assertEquals;
+
 /**
  * Unit tests for {@link ScriptTemplateViewResolver}.
  *
@@ -31,10 +32,10 @@ public class ScriptTemplateViewResolverTests {
 	@Test
 	public void viewClass() throws Exception {
 		ScriptTemplateViewResolver resolver = new ScriptTemplateViewResolver();
-		Assert.assertEquals(ScriptTemplateView.class, resolver.requiredViewClass());
+		assertEquals(ScriptTemplateView.class, resolver.requiredViewClass());
 		DirectFieldAccessor viewAccessor = new DirectFieldAccessor(resolver);
 		Class<?> viewClass = (Class<?>) viewAccessor.getPropertyValue("viewClass");
-		Assert.assertEquals(ScriptTemplateView.class, viewClass);
+		assertEquals(ScriptTemplateView.class, viewClass);
 	}
 
 }

src/checkstyle/checkstyle.xml

@@ -97,7 +97,7 @@
 		<module name="com.puppycrawl.tools.checkstyle.checks.imports.IllegalImportCheck">
 			<property name="regexp" value="true" />
 			<property name="illegalClasses"
-				value="^reactor\.core\.support\.Assert,^junit\.framework\..+,^org\.junit\.Assert\.assertThat,^org\.junit\.Assume\.assumeThat,^org\.junit\.rules\.ExpectedException,^org\.slf4j\.LoggerFactory" />
+				value="^reactor\.core\.support\.Assert,^junit\.framework\..+,^org\.junit\.Assert$,^org\.junit\.Assume$,^org\.junit\.Assert\.assertThat,^org\.junit\.Assume\.assumeThat,^org\.junit\.rules\.ExpectedException,^org\.slf4j\.LoggerFactory" />
 		</module>
 
 		<!-- Javadoc Comments -->