Support target type in JsonPath assertions

This change adds support for a target type in JsonPath assertions in
Spring MVC Test.

The existing assertValue(String expression, Object expectedValue)
transparently falls back on using an alternative JsonPath API that
allows specifying the target type to coerce to.

There is also a new overloaded method
assertValue(String expression, Matcher<T> matcher, Class<T> targetType)
for use with Hamcrest matchers where the target type can be specified.

Issue: SPR-14498
(cherry picked from commit 7fdb892)

Author: rstoyanchev

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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 +16,9 @@
 
 package org.springframework.test.util;
 
-import java.text.ParseException;
 import java.util.List;
 import java.util.Map;
 
-import com.jayway.jsonpath.InvalidPathException;
 import com.jayway.jsonpath.JsonPath;
 import org.hamcrest.Matcher;
 
@@ -71,18 +69,33 @@ public JsonPathExpectationsHelper(String expression, Object... args) {
 	 * @param matcher the matcher with which to assert the result
 	 */
 	@SuppressWarnings("unchecked")
-	public <T> void assertValue(String content, Matcher<T> matcher) throws ParseException {
+	public <T> void assertValue(String content, Matcher<T> matcher) {
 		T value = (T) evaluateJsonPath(content);
 		assertThat("JSON path \"" + this.expression + "\"", value, matcher);
 	}
 
+	/**
+	 * An overloaded variant of {@link #assertValue(String, Matcher)} that also
+	 * accepts a target type for the resulting value. This can be useful for
+	 * matching numbers reliably for example coercing an integer into a double.
+	 * @param content the JSON content
+	 * @param matcher the matcher with which to assert the result
+	 * @param targetType a the expected type of the resulting value
+	 * @since 4.3.3
+	 */
+	@SuppressWarnings("unchecked")
+	public <T> void assertValue(String content, Matcher<T> matcher, Class<T> targetType) {
+		T value = (T) evaluateJsonPath(content, targetType);
+		assertThat("JSON path \"" + this.expression + "\"", value, matcher);
+	}
+
 	/**
 	 * Evaluate the JSON path expression against the supplied {@code content}
 	 * and assert that the result is equal to the expected value.
 	 * @param content the JSON content
 	 * @param expectedValue the expected value
 	 */
-	public void assertValue(String content, Object expectedValue) throws ParseException {
+	public void assertValue(String content, Object expectedValue) {
 		Object actualValue = evaluateJsonPath(content);
 		if ((actualValue instanceof List) && !(expectedValue instanceof List)) {
 			@SuppressWarnings("rawtypes")
@@ -96,8 +109,9 @@ public void assertValue(String content, Object expectedValue) throws ParseExcept
 			actualValue = actualValueList.get(0);
 		}
 		else if (actualValue != null && expectedValue != null) {
-			assertEquals("At JSON path \"" + this.expression + "\", type of value",
-					expectedValue.getClass().getName(), actualValue.getClass().getName());
+			if (!actualValue.getClass().equals(expectedValue.getClass())) {
+				actualValue = evaluateJsonPath(content, expectedValue.getClass());
+			}
 		}
 		assertEquals("JSON path \"" + this.expression + "\"", expectedValue, actualValue);
 	}
@@ -108,7 +122,7 @@ else if (actualValue != null && expectedValue != null) {
 	 * @param content the JSON content
 	 * @since 4.2.1
 	 */
-	public void assertValueIsString(String content) throws ParseException {
+	public void assertValueIsString(String content) {
 		Object value = assertExistsAndReturn(content);
 		assertThat(failureReason("a string", value), value, instanceOf(String.class));
 	}
@@ -119,7 +133,7 @@ public void assertValueIsString(String content) throws ParseException {
 	 * @param content the JSON content
 	 * @since 4.2.1
 	 */
-	public void assertValueIsBoolean(String content) throws ParseException {
+	public void assertValueIsBoolean(String content) {
 		Object value = assertExistsAndReturn(content);
 		assertThat(failureReason("a boolean", value), value, instanceOf(Boolean.class));
 	}
@@ -130,7 +144,7 @@ public void assertValueIsBoolean(String content) throws ParseException {
 	 * @param content the JSON content
 	 * @since 4.2.1
 	 */
-	public void assertValueIsNumber(String content) throws ParseException {
+	public void assertValueIsNumber(String content) {
 		Object value = assertExistsAndReturn(content);
 		assertThat(failureReason("a number", value), value, instanceOf(Number.class));
 	}
@@ -140,7 +154,7 @@ public void assertValueIsNumber(String content) throws ParseException {
 	 * and assert that the resulting value is an array.
 	 * @param content the JSON content
 	 */
-	public void assertValueIsArray(String content) throws ParseException {
+	public void assertValueIsArray(String content) {
 		Object value = assertExistsAndReturn(content);
 		assertThat(failureReason("an array", value), value, instanceOf(List.class));
 	}
@@ -151,7 +165,7 @@ public void assertValueIsArray(String content) throws ParseException {
 	 * @param content the JSON content
 	 * @since 4.2.1
 	 */
-	public void assertValueIsMap(String content) throws ParseException {
+	public void assertValueIsMap(String content) {
 		Object value = assertExistsAndReturn(content);
 		assertThat(failureReason("a map", value), value, instanceOf(Map.class));
 	}
@@ -164,7 +178,7 @@ public void assertValueIsMap(String content) throws ParseException {
 	 * that the value at the given path is not <em>empty</em>.
 	 * @param content the JSON content
 	 */
-	public void exists(String content) throws ParseException {
+	public void exists(String content) {
 		assertExistsAndReturn(content);
 	}
 
@@ -176,7 +190,7 @@ public void exists(String content) throws ParseException {
 	 * that the value at the given path is <em>empty</em>.
 	 * @param content the JSON content
 	 */
-	public void doesNotExist(String content) throws ParseException {
+	public void doesNotExist(String content) {
 		Object value;
 		try {
 			value = evaluateJsonPath(content);
@@ -189,7 +203,7 @@ public void doesNotExist(String content) throws ParseException {
 			assertTrue(reason, ((List<?>) value).isEmpty());
 		}
 		else {
-			assertTrue(reason, value == null);
+			assertTrue(reason, (value == null));
 		}
 	}
 
@@ -200,7 +214,7 @@ public void doesNotExist(String content) throws ParseException {
 	 * {@link ObjectUtils#isEmpty(Object)}.
 	 * @param content the JSON content
 	 */
-	public void assertValueIsEmpty(String content) throws ParseException {
+	public void assertValueIsEmpty(String content) {
 		Object value = evaluateJsonPath(content);
 		assertTrue(failureReason("an empty value", value), ObjectUtils.isEmpty(value));
 	}
@@ -212,33 +226,37 @@ public void assertValueIsEmpty(String content) throws ParseException {
 	 * {@link ObjectUtils#isEmpty(Object)}.
 	 * @param content the JSON content
 	 */
-	public void assertValueIsNotEmpty(String content) throws ParseException {
+	public void assertValueIsNotEmpty(String content) {
 		Object value = evaluateJsonPath(content);
 		assertTrue(failureReason("a non-empty value", value), !ObjectUtils.isEmpty(value));
 	}
 
 	private String failureReason(String expectedDescription, Object value) {
 		return String.format("Expected %s at JSON path \"%s\" but found: %s", expectedDescription, this.expression,
-			ObjectUtils.nullSafeToString(StringUtils.quoteIfString(value)));
+				ObjectUtils.nullSafeToString(StringUtils.quoteIfString(value)));
 	}
 
-	private Object evaluateJsonPath(String content) throws ParseException {
+	private Object evaluateJsonPath(String content) {
 		String message = "No value at JSON path \"" + this.expression + "\", exception: ";
 		try {
 			return this.jsonPath.read(content);
 		}
-		catch (InvalidPathException ex) {
+		catch (Throwable ex) {
 			throw new AssertionError(message + ex.getMessage());
 		}
-		catch (ArrayIndexOutOfBoundsException ex) {
-			throw new AssertionError(message + ex.getMessage());
+	}
+
+	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 (IndexOutOfBoundsException ex) {
+		catch (Throwable ex) {
 			throw new AssertionError(message + ex.getMessage());
 		}
 	}
 
-	private Object assertExistsAndReturn(String content) throws ParseException {
+	private Object assertExistsAndReturn(String content) {
 		Object value = evaluateJsonPath(content);
 		String reason = "No value at JSON path \"" + this.expression + "\"";
 		assertTrue(reason, value != null);

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

@@ -69,6 +69,23 @@ 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.
+	 * @since 4.3.3
+	 */
+	public <T> RequestMatcher value(final Matcher<T> matcher, final Class<T> targetType) {
+		return new AbstractJsonPathRequestMatcher() {
+			@Override
+			protected void matchInternal(MockClientHttpRequest request) throws IOException, ParseException {
+				String body = request.getBodyAsString();
+				JsonPathRequestMatchers.this.jsonPathHelper.assertValue(body, matcher, targetType);
+			}
+		};
+	}
+
 	/**
 	 * Evaluate the JSON path expression against the request content and
 	 * assert that the result is equal to the supplied value.

spring-test/src/test/java/org/springframework/test/util/JsonPathExpectationsHelperTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2004-2015 the original author or authors.
+ * Copyright 2004-2016 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.
@@ -20,7 +20,7 @@
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 
-import static org.hamcrest.CoreMatchers.*;
+import static org.hamcrest.core.Is.*;
 
 /**
  * Unit tests for {@link JsonPathExpectationsHelper}.
@@ -222,11 +222,14 @@ public void assertValue() throws Exception {
 		new JsonPathExpectationsHelper("$.num").assertValue(CONTENT, 5);
 	}
 
-	@Test
-	public void assertValueWithDifferentExpectedType() throws Exception {
-		exception.expect(AssertionError.class);
-		exception.expectMessage(equalTo("At JSON path \"$.num\", type of value expected:<java.lang.String> but was:<java.lang.Integer>"));
-		new JsonPathExpectationsHelper("$.num").assertValue(CONTENT, "5");
+	@Test // SPR-14498
+	public void assertValueWithNumberConversion() throws Exception {
+		new JsonPathExpectationsHelper("$.num").assertValue(CONTENT, 5.0);
+	}
+
+	@Test // SPR-14498
+	public void assertValueWithNumberConversionAndMatcher() throws Exception {
+		new JsonPathExpectationsHelper("$.num").assertValue(CONTENT, is(5.0), Double.class);
 	}
 
 	@Test