Fix tests for JSON error rendering

See gh-1762

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/DefaultErrorAttributes.java

@@ -122,7 +122,7 @@ private void addErrorDetails(Map<String, Object> errorAttributes,
 			}
 		}
 		Object message = getAttribute(requestAttributes, "javax.servlet.error.message");
-		if (message != null || errorAttributes.get("message") == null) {
+		if ((message != null || errorAttributes.get("message") == null) && !(error instanceof BindingResult)) {
 			errorAttributes.put("message", message == null ? "No message available"
 					: message);
 		}

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/BasicErrorControllerIntegrationTests.java

@@ -33,6 +33,7 @@
 import org.springframework.boot.test.TestRestTemplate;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.RequestEntity;
 import org.springframework.http.ResponseEntity;
@@ -41,6 +42,7 @@
 import org.springframework.test.context.web.WebAppConfiguration;
 import org.springframework.validation.BindException;
 import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.ResponseStatus;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.view.AbstractView;
@@ -73,8 +75,21 @@ public void testErrorForMachineClient() throws Exception {
 				"http://localhost:" + this.port, Map.class);
 		assertThat(entity.getBody().toString(), endsWith("status=500, "
 				+ "error=Internal Server Error, "
-				+ "exception=java.lang.IllegalStateException, " + "message=Expected!, "
-				+ "path=/}"));
+				+ "exception=java.lang.IllegalStateException, "
+				+ "message=Server Error, " + "path=/}"));
+	}
+
+	@Test
+	@SuppressWarnings("rawtypes")
+	public void testErrorForAnnotatedException() throws Exception {
+		ResponseEntity<Map> entity = new TestRestTemplate().getForEntity(
+				"http://localhost:" + this.port + "/annotated", Map.class);
+		assertThat(
+				entity.getBody().toString(),
+				endsWith("status=400, "
+						+ "error=Bad Request, "
+						+ "exception=org.springframework.boot.autoconfigure.web.BasicErrorControllerIntegrationTests$TestConfiguration$Errors$ExpectedException, "
+						+ "message=Expected!, " + "path=/annotated}"));
 	}
 
 	@Test
@@ -124,13 +139,24 @@ public String home() {
 				throw new IllegalStateException("Expected!");
 			}
 
+			@RequestMapping("/annotated")
+			public String annotated() {
+				throw new ExpectedException();
+			}
+
 			@RequestMapping("/bind")
 			public String bind(HttpServletRequest request) throws Exception {
 				BindException error = new BindException(this, "test");
 				error.rejectValue("foo", "bar.error");
 				throw error;
 			}
 
+			@ResponseStatus(value = HttpStatus.BAD_REQUEST, reason = "Expected!")
+			@SuppressWarnings("serial")
+			private static class ExpectedException extends RuntimeException {
+
+			}
+
 		}
 
 	}