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

Author: sbrannen

Diff for: spring-test/src/main/java/org/springframework/test/util/JsonPathExpectationsHelper.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.
@@ -237,22 +237,22 @@ private String failureReason(String expectedDescription, Object value) {
 	}
 
 	private Object evaluateJsonPath(String content) {
-		String message = "No value at JSON path \"" + this.expression + "\", exception: ";
 		try {
 			return this.jsonPath.read(content);
 		}
 		catch (Throwable ex) {
-			throw new AssertionError(message + ex.getMessage());
+			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 + "\", exception: ";
 		try {
 			return JsonPath.parse(content).read(this.expression, targetType);
 		}
 		catch (Throwable ex) {
-			throw new AssertionError(message + ex.getMessage());
+			String message = "No value at JSON path \"" + this.expression + "\"";
+			throw new AssertionError(message, ex);
 		}
 	}
 

Diff for: 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 @@
 /**
  * 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 @@ protected void matchInternal(MockClientHttpRequest request) throws IOException,
 	}
 
 	/**
-	 * An overloaded variant of (@link {@link #value(Matcher)} that also
-	 * accepts a target type for the resulting value that the matcher can work
-	 * reliably against. This can be useful for matching numbers reliably for
-	 * example coercing an integer into a double.
+	 * 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 4.3.3
 	 */
 	public <T> RequestMatcher value(final Matcher<T> matcher, final Class<T> targetType) {

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

@@ -219,7 +219,7 @@ public static ContentRequestMatchers content() {
 	 * @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);
 	}
 

Diff for: 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.
@@ -78,6 +78,8 @@ public JsonPathResultMatchers prefix(String prefix) {
 	/**
 	 * 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) {
 		return new ResultMatcher() {
@@ -89,9 +91,31 @@ public void match(MvcResult result) throws Exception {
 		};
 	}
 
+	/**
+	 * 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 new ResultMatcher() {
+			@Override
+			public void match(MvcResult result) throws Exception {
+				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) {
 		return new ResultMatcher() {

Diff for: spring-test/src/main/java/org/springframework/test/web/servlet/result/MockMvcResultMatchers.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.
@@ -176,7 +176,7 @@ public static ContentResultMatchers content() {
 	 * @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);
 	}
 

Diff for: 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.
@@ -55,23 +55,33 @@ 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)
-	public void valueNoMatch() throws Exception {
-		new JsonPathRequestMatchers("$.str").value("bogus").match(request);
+	@Test // SPR-14498
+	public void valueWithNumberConversion() throws Exception {
+		new JsonPathRequestMatchers("$.num").value(5.0f).match(request);
 	}
 
 	@Test
 	public void valueWithMatcher() throws Exception {
 		new JsonPathRequestMatchers("$.str").value(equalTo("foo")).match(request);
 	}
 
+	@Test // SPR-14498
+	public void valueWithMatcherAndNumberConversion() throws Exception {
+		new JsonPathRequestMatchers("$.num").value(equalTo(5.0f), Float.class).match(request);
+	}
+
 	@Test(expected = AssertionError.class)
-	public void valueWithMatcherNoMatch() throws Exception {
+	public void valueWithMatcherAndMismatch() throws Exception {
 		new JsonPathRequestMatchers("$.str").value(equalTo("bogus")).match(request);
 	}
 

Diff for: 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.
@@ -58,23 +58,33 @@ 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)
-	public void valueNoMatch() throws Exception {
-		new JsonPathResultMatchers("$.str").value("bogus").match(stubMvcResult);
+	@Test // SPR-16587
+	public void valueWithNumberConversion() throws Exception {
+		new JsonPathResultMatchers("$.num").value(5.0f).match(stubMvcResult);
 	}
 
 	@Test
 	public void valueWithMatcher() throws Exception {
 		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);
 	}