Consider empty arrays as existent in JsonPath assertions

Prior to this commit, a JsonPath assertion that a path expression
evaluated to an array in JsonPathExpectationsHelper (and therefore
indirectly in JsonPathResultMatchers in Spring MVC Test) would
incorrectly fail if the array was present in the JSON content but empty.

This commit fixes this issue by removing the "not empty" check for
arrays and lists.

Issue: SPR-13320

Author: sbrannen

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

@@ -238,9 +238,6 @@ private Object assertExistsAndReturn(String content) throws ParseException {
 		Object value = evaluateJsonPath(content);
 		String reason = "No value for JSON path \"" + this.expression + "\"";
 		assertTrue(reason, value != null);
-		if (List.class.isInstance(value)) {
-			assertTrue(reason, !((List<?>) value).isEmpty());
-		}
 		return value;
 	}
 

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

@@ -106,6 +106,11 @@ public void assertValueIsArray() throws Exception {
 		new JsonPathExpectationsHelper("$.arr").assertValueIsArray(CONTENT);
 	}
 
+	@Test
+	public void assertValueIsArrayForAnEmptyArray() throws Exception {
+		new JsonPathExpectationsHelper("$.emptyArray").assertValueIsArray(CONTENT);
+	}
+
 	@Test
 	public void assertValueIsArrayForNonArray() throws Exception {
 		exception.expect(AssertionError.class);
@@ -117,6 +122,11 @@ public void assertValueIsMap() throws Exception {
 		new JsonPathExpectationsHelper("$.colorMap").assertValueIsMap(CONTENT);
 	}
 
+	@Test
+	public void assertValueIsMapForAnEmptyMap() throws Exception {
+		new JsonPathExpectationsHelper("$.emptyMap").assertValueIsMap(CONTENT);
+	}
+
 	@Test
 	public void assertValueIsMapForNonMap() throws Exception {
 		exception.expect(AssertionError.class);

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

@@ -32,7 +32,7 @@
  */
 public class JsonPathResultMatchersTests {
 
-	private static final String RESPONSE_CONTENT = "{\"foo\": \"bar\", \"qux\": [\"baz\"], \"emptyArray\": [], \"icanhaz\": true, \"howmanies\": 5, \"cheeseburger\": {\"pickles\": true} }";
+	private static final String RESPONSE_CONTENT = "{\"foo\": \"bar\", \"qux\": [\"baz\"], \"emptyArray\": [], \"icanhaz\": true, \"howmanies\": 5, \"cheeseburger\": {\"pickles\": true}, \"emptyMap\": {} }";
 
 	private static final StubMvcResult stubMvcResult;
 
@@ -93,13 +93,32 @@ public void doesNotExistNoMatch() throws Exception {
 	public void isArray() throws Exception {
 		new JsonPathResultMatchers("$.qux").isArray().match(stubMvcResult);
 	}
+
+	@Test
+	public void isArrayForAnEmptyArray() throws Exception {
+		new JsonPathResultMatchers("$.emptyArray").isArray().match(stubMvcResult);
 	}
 
 	@Test(expected = AssertionError.class)
 	public void isArrayNoMatch() throws Exception {
 		new JsonPathResultMatchers("$.bar").isArray().match(stubMvcResult);
 	}
 
+	@Test
+	public void isMap() throws Exception {
+		new JsonPathResultMatchers("$.cheeseburger").isMap().match(stubMvcResult);
+	}
+
+	@Test
+	public void isMapForAnEmptyMap() throws Exception {
+		new JsonPathResultMatchers("$.emptyMap").isMap().match(stubMvcResult);
+	}
+
+	@Test(expected = AssertionError.class)
+	public void isMapNoMatch() throws Exception {
+		new JsonPathResultMatchers("$.foo").isMap().match(stubMvcResult);
+	}
+
 	@Test
 	public void isBoolean() throws Exception {
 		new JsonPathResultMatchers("$.icanhaz").isBoolean().match(stubMvcResult);
@@ -120,16 +139,6 @@ public void isNumberNoMatch() throws Exception {
 		new JsonPathResultMatchers("$.foo").isNumber().match(stubMvcResult);
 	}
 
-	@Test
-	public void isMap() throws Exception {
-		new JsonPathResultMatchers("$.cheeseburger").isMap().match(stubMvcResult);
-	}
-
-	@Test(expected = AssertionError.class)
-	public void isMapNoMatch() throws Exception {
-		new JsonPathResultMatchers("$.foo").isMap().match(stubMvcResult);
-	}
-
 	@Test
 	public void isString() throws Exception {
 		new JsonPathResultMatchers("$.foo").isString().match(stubMvcResult);