DATAREST-889 - Polishing.

Improved test cases by using JUnit's ExpectedException for simpler assertions.

Original pull request: #227.

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/json/patch/JsonLateObjectEvaluator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 the original author or authors.
+ * Copyright 2014-2016 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.
@@ -25,6 +25,8 @@ import com.fasterxml.jackson.databind.ObjectMapper;
  * {@link LateObjectEvaluator} implementation that assumes values represented as JSON objects.
  * 
  * @author Craig Walls
+ * @author Oliver Trosien
+ * @author Oliver Gierke
  */
 @RequiredArgsConstructor
 class JsonLateObjectEvaluator implements LateObjectEvaluator {
@@ -42,7 +44,7 @@ class JsonLateObjectEvaluator implements LateObjectEvaluator {
 		try {
 			return mapper.readValue(valueNode.traverse(), type);
 		} catch (Exception e) {
-			throw new PatchException("JSON deserialization exception", e);
+			throw new PatchException(String.format("Could not read %s into %s!", valueNode, type), e);
 		}
 	}
 }

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/json/patch/JsonPatchPatchConverter.java

@@ -140,6 +140,8 @@ public class JsonPatchPatchConverter implements PatchConverter<JsonNode> {
 		} else if (valueNode.isObject() || (valueNode.isArray())) {
 			return new JsonLateObjectEvaluator(mapper, valueNode);
 		}
-		throw new PatchException("Unrecognized valueNode type at path: " + path + ". valueNode: " + valueNode.toString());
+
+		throw new PatchException(
+				String.format("Unrecognized valueNode type at path %s and value node %s.", path, valueNode));
 	}
 }

spring-data-rest-webmvc/src/test/java/org/springframework/data/rest/webmvc/json/patch/JsonPatchTests.java

@@ -23,7 +23,9 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.springframework.core.io.ClassPathResource;
 
 import com.fasterxml.jackson.core.JsonParseException;
@@ -41,6 +43,8 @@ import com.fasterxml.jackson.databind.ObjectMapper;
  */
 public class JsonPatchTests {
 
+	public @Rule ExpectedException exception = ExpectedException.none();
+
 	@Test
 	public void manySuccessfulOperations() throws Exception {
 
@@ -118,7 +122,7 @@ public class JsonPatchTests {
 	}
 
 	/**
-	 * @see DATAREST-885
+	 * @see DATAREST-889
 	 */
 	@Test
 	public void patchArray() throws Exception {
@@ -132,34 +136,39 @@ public class JsonPatchTests {
 		assertEquals(Arrays.asList("one", "two", "three"), patchedTodo.getItems());
 	}
 
+	/**
+	 * @see DATAREST-889
+	 */
 	@Test
 	public void patchUnknownType() throws Exception {
+
 		Todo todo = new Todo();
 		todo.setAmount(BigInteger.ONE);
 
-		try {
-			Patch patch = readJsonPatch("patch-biginteger.json");
-			assertEquals(1, patch.size());
-			assertEquals(new BigInteger("18446744073709551616"), patch.getOperations().get(0).value);
-		} catch (PatchException e) {
-			assertEquals("Unrecognized valueNode type at path: /amount. valueNode: 18446744073709551616", e.getMessage());
-		}
+		exception.expect(PatchException.class);
+		exception.expectMessage("/amount");
+		exception.expectMessage("18446744073709551616");
+
+		readJsonPatch("patch-biginteger.json");
 	}
 
+	/**
+	 * @see DATAREST-889
+	 */
 	@Test
 	public void failureWithInvalidPatchContent() throws Exception {
+
 		Todo todo = new Todo();
 		todo.setDescription("Description");
 
 		Patch patch = readJsonPatch("patch-failing-with-invalid-content.json");
-		assertEquals(1, patch.size());
 
-		try {
-			Todo patchedTodo = patch.apply(todo, Todo.class);
-			assertEquals("Description", patchedTodo.getDescription());
-		} catch (PatchException e) {
-			assertEquals("JSON deserialization exception", e.getMessage());
-		}
+		exception.expect(PatchException.class);
+		exception.expectMessage("content");
+		exception.expectMessage("blabla");
+		exception.expectMessage(String.class.toString());
+
+		patch.apply(todo, Todo.class);
 	}
 
 	private Patch readJsonPatch(String jsonPatchFile) throws IOException, JsonParseException, JsonMappingException {