Support target type in JsonPath assertions for MockMvc results

This commit picks up where SPR-14498 left off by adding support for an
explicit target type when using JsonPath to perform an assertion against
the response content using a Hamcrest Matcher.

Specifically, there is a new overloaded value(Matcher<T>, Class<T>)
method in JsonPathResultMatchers for use with Hamcrest matchers where
the target type (i.e., Class<T>) can be specified.

Issue: SPR-16587

spring-test/src/main/java/org/springframework/test/util/JsonPathExpectationsHelper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -282,21 +282,21 @@ public class JsonPathExpectationsHelper {
 
 	@Nullable
 	private Object evaluateJsonPath(String content) {
-		String message = "No value at JSON path \"" + this.expression + "\"";
 		try {
 			return this.jsonPath.read(content);
 		}
 		catch (Throwable ex) {
+			String message = "No value at JSON path \"" + this.expression + "\"";
 			throw new AssertionError(message, ex);
 		}
 	}
 
 	private Object evaluateJsonPath(String content, Class<?> targetType) {
-		String message = "No value at JSON path \"" + this.expression + "\"";
 		try {
 			return JsonPath.parse(content).read(this.expression, targetType);
 		}
 		catch (Throwable ex) {
+			String message = "No value at JSON path \"" + this.expression + "\"";
 			throw new AssertionError(message, ex);
 		}
 	}

spring-test/src/main/java/org/springframework/test/web/client/match/JsonPathRequestMatchers.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -30,6 +30,7 @@ import org.springframework.test.web.client.RequestMatcher;
 /**
  * Factory for assertions on the request content using
  * <a href="https://github.com/jayway/JsonPath">JsonPath</a> expressions.
+ *
  * <p>An instance of this class is typically accessed via
  * {@link MockRestRequestMatchers#jsonPath(String, Matcher)} or
  * {@link MockRestRequestMatchers#jsonPath(String, Object...)}.
@@ -70,10 +71,11 @@ public class JsonPathRequestMatchers {
 	}
 
 	/**
-	 * An overloaded variant of (@link {@link #value(Matcher)} that also
+	 * An overloaded variant of {@link #value(Matcher)} that also accepts a
-	 * accepts a target type for the resulting value that the matcher can work
+	 * target type for the resulting value that the matcher can work reliably
-	 * reliably against. This can be useful for matching numbers reliably for
+	 * against.
-	 * example coercing an integer into a double.
+	 * <p>This can be useful for matching numbers reliably &mdash; for example,
+	 * to coerce an integer into a double.
 	 * @since 4.3.3
 	 */
 	public <T> RequestMatcher value(final Matcher<T> matcher, final Class<T> targetType) {

spring-test/src/main/java/org/springframework/test/web/client/match/MockRestRequestMatchers.java

@@ -199,7 +199,7 @@ public abstract class MockRestRequestMatchers {
 	 * @param expression the JSON path optionally parameterized with arguments
 	 * @param args arguments to parameterize the JSON path expression with
 	 */
-	public static JsonPathRequestMatchers jsonPath(String expression, Object ... args) {
+	public static JsonPathRequestMatchers jsonPath(String expression, Object... args) {
 		return new JsonPathRequestMatchers(expression, args);
 	}
 

spring-test/src/main/java/org/springframework/test/web/servlet/result/JsonPathResultMatchers.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -80,19 +80,40 @@ public class JsonPathResultMatchers {
 	/**
 	 * Evaluate the JSON path expression against the response content and
 	 * assert the resulting value with the given Hamcrest {@link Matcher}.
+	 * @see #value(Matcher, Class)
+	 * @see #value(Object)
 	 */
-	public <T> ResultMatcher value(final Matcher<T> matcher) {
+	public <T> ResultMatcher value(Matcher<T> matcher) {
 		return result -> {
 			String content = getContent(result);
 			jsonPathHelper.assertValue(content, matcher);
 		};
 	}
 
+	/**
+	 * An overloaded variant of {@link #value(Matcher)} that also accepts a
+	 * target type for the resulting value that the matcher can work reliably
+	 * against.
+	 * <p>This can be useful for matching numbers reliably &mdash; for example,
+	 * to coerce an integer into a double.
+	 * @since 4.3.15
+	 * @see #value(Matcher)
+	 * @see #value(Object)
+	 */
+	public <T> ResultMatcher value(Matcher<T> matcher, Class<T> targetType) {
+		return result -> {
+			String content = getContent(result);
+			jsonPathHelper.assertValue(content, matcher, targetType);
+		};
+	}
+
 	/**
 	 * Evaluate the JSON path expression against the response content and
 	 * assert that the result is equal to the supplied value.
+	 * @see #value(Matcher)
+	 * @see #value(Matcher, Class)
 	 */
-	public ResultMatcher value(final Object expectedValue) {
+	public ResultMatcher value(Object expectedValue) {
 		return result -> jsonPathHelper.assertValue(getContent(result), expectedValue);
 	}
 

spring-test/src/main/java/org/springframework/test/web/servlet/result/MockMvcResultMatchers.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -186,7 +186,7 @@ public abstract class MockMvcResultMatchers {
 	 * @param expression the JSON path expression, optionally parameterized with arguments
 	 * @param args arguments to parameterize the JSON path expression with
 	 */
-	public static JsonPathResultMatchers jsonPath(String expression, Object ... args) {
+	public static JsonPathResultMatchers jsonPath(String expression, Object... args) {
 		return new JsonPathResultMatchers(expression, args);
 	}
 

spring-test/src/test/java/org/springframework/test/web/client/match/JsonPathRequestMatchersTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -18,6 +18,8 @@ package org.springframework.test.web.client.match;
 
 import java.io.IOException;
 
+import org.hamcrest.Matchers;
+
 import org.junit.Test;
 
 import org.springframework.mock.http.client.MockClientHttpRequest;
@@ -55,14 +57,19 @@ public class JsonPathRequestMatchersTests {
 	}
 
 
+	@Test(expected = AssertionError.class)
+	public void valueWithMismatch() throws Exception {
+		new JsonPathRequestMatchers("$.str").value("bogus").match(request);
+	}
+
 	@Test
-	public void value() throws Exception {
+	public void valueWithDirectMatch() throws Exception {
 		new JsonPathRequestMatchers("$.str").value("foo").match(request);
 	}
 
-	@Test(expected = AssertionError.class)
+	@Test // SPR-14498
-	public void valueNoMatch() throws Exception {
+	public void valueWithNumberConversion() throws Exception {
-		new JsonPathRequestMatchers("$.str").value("bogus").match(request);
+		new JsonPathRequestMatchers("$.num").value(5.0f).match(request);
 	}
 
 	@Test
@@ -70,8 +77,13 @@ public class JsonPathRequestMatchersTests {
 		new JsonPathRequestMatchers("$.str").value(equalTo("foo")).match(request);
 	}
 
+	@Test // SPR-14498
+	public void valueWithMatcherAndNumberConversion() throws Exception {
+		new JsonPathRequestMatchers("$.num").value(Matchers.equalTo(5.0f), Float.class).match(request);
+	}
+
 	@Test(expected = AssertionError.class)
-	public void valueWithMatcherNoMatch() throws Exception {
+	public void valueWithMatcherAndMismatch() throws Exception {
 		new JsonPathRequestMatchers("$.str").value(equalTo("bogus")).match(request);
 	}
 

spring-test/src/test/java/org/springframework/test/web/servlet/result/JsonPathResultMatchersTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -58,14 +58,19 @@ public class JsonPathResultMatchersTests {
 		}
 	}
 
+	@Test(expected = AssertionError.class)
+	public void valueWithMismatch() throws Exception {
+		new JsonPathResultMatchers("$.str").value("bogus").match(stubMvcResult);
+	}
+
 	@Test
-	public void value() throws Exception {
+	public void valueWithDirectMatch() throws Exception {
 		new JsonPathResultMatchers("$.str").value("foo").match(stubMvcResult);
 	}
 
-	@Test(expected = AssertionError.class)
+	@Test // SPR-16587
-	public void valueNoMatch() throws Exception {
+	public void valueWithNumberConversion() throws Exception {
-		new JsonPathResultMatchers("$.str").value("bogus").match(stubMvcResult);
+		new JsonPathResultMatchers("$.num").value(5.0f).match(stubMvcResult);
 	}
 
 	@Test
@@ -73,8 +78,13 @@ public class JsonPathResultMatchersTests {
 		new JsonPathResultMatchers("$.str").value(Matchers.equalTo("foo")).match(stubMvcResult);
 	}
 
+	@Test // SPR-16587
+	public void valueWithMatcherAndNumberConversion() throws Exception {
+		new JsonPathResultMatchers("$.num").value(Matchers.equalTo(5.0f), Float.class).match(stubMvcResult);
+	}
+
 	@Test(expected = AssertionError.class)
-	public void valueWithMatcherNoMatch() throws Exception {
+	public void valueWithMatcherAndMismatch() throws Exception {
 		new JsonPathResultMatchers("$.str").value(Matchers.equalTo("bogus")).match(stubMvcResult);
 	}