Raise exception for any field error in retrieve

This commit aligns the behavior of retrieve with its Javadoc such that
any field error, including errors on nested fields, raises a
FieldAccessException

Closes gh-499

Author: rstoyanchev

Diff for: spring-graphql/src/main/java/org/springframework/graphql/client/DefaultGraphQlClient.java

@@ -186,13 +186,16 @@ protected RetrieveSpecSupport(String path) {
 		}
 
 		/**
-		 * Return the field if valid, or {@code null} if {@code null} without errors.
-		 * @throws FieldAccessException for invalid response or failed field
+		 * Return the field or {@code null}, but only if the response is valid
+		 * and there are no field errors, or raise {@link FieldAccessException}
+		 * otherwise.
+		 * @throws FieldAccessException in case of an invalid response or any
+		 * field error at, above or below the field path
 		 */
 		@Nullable
 		protected ClientResponseField getValidField(ClientGraphQlResponse response) {
 			ClientResponseField field = response.field(this.path);
-			if (!response.isValid() || field.getError() != null) {
+			if (!response.isValid() || !field.getErrors().isEmpty()) {
 				throw new FieldAccessException(
 						((DefaultClientGraphQlResponse) response).getRequest(), response, field);
 			}

Diff for: spring-graphql/src/main/java/org/springframework/graphql/client/GraphQlClient.java

@@ -191,8 +191,8 @@ interface RequestSpec {
 		 * client.document("..").execute().map(response -> response.toEntity(..))
 		 * </pre>
 		 * @return a spec with decoding options
-		 * @throws FieldAccessException if the target field has any errors,
-		 * including nested errors.
+		 * @throws FieldAccessException if the field has any field errors,
+		 * including errors at, above or below the field path.
 		 */
 		RetrieveSpec retrieve(String path);
 

Diff for: spring-graphql/src/main/java/org/springframework/graphql/support/AbstractGraphQlResponse.java

@@ -133,7 +133,7 @@ private static Object initFieldValue(List<Object> path, GraphQlResponse response
 		}
 
 		/**
-		 * Return field errors whose path starts with the given field path.
+		 * Return errors whose path is at, above, or below the given path.
 		 * @param path the field path to match
 		 * @return errors whose path starts with the dataPath
 		 */
@@ -144,7 +144,7 @@ private static List<ResponseError> initFieldErrors(String path, GraphQlResponse
 			return response.getErrors().stream()
 					.filter(error -> {
 						String errorPath = error.getPath();
-						return !errorPath.isEmpty() && (errorPath.startsWith(path) || path.startsWith(errorPath));
+						return (!errorPath.isEmpty() && (errorPath.startsWith(path) || path.startsWith(errorPath)));
 					})
 					.collect(Collectors.toList());
 		}

Diff for: spring-graphql/src/test/java/org/springframework/graphql/client/GraphQlClientTests.java

@@ -130,14 +130,23 @@ void retrieveInvalidResponse() {
 	}
 
 	@Test
-	void retrievePartialResponse() {
+	void retrieveFieldErrorAt() {
+		String document = "fieldErrorResponse";
+		getGraphQlService().setDataAsJsonAndErrors(document, "{\"me\": null}", errorForPath("/me"));
+		testRetrieveFieldAccessException(document, "me");
+	}
 
+	@Test // gh-499
+	void retrieveFieldErrorBelow() {
 		String document = "fieldErrorResponse";
 		getGraphQlService().setDataAsJsonAndErrors(document, "{\"me\": {\"name\":null}}", errorForPath("/me/name"));
+		testRetrieveFieldAccessException(document, "me");
+	}
 
-		MovieCharacter character = graphQlClient().document(document).retrieve("me").toEntity(MovieCharacter.class).block();
-		assertThat(character).isNotNull().extracting(MovieCharacter::getName).isNull();
-
+	@Test
+	void retrieveFieldErrorAbove() {
+		String document = "fieldErrorResponse";
+		getGraphQlService().setDataAsJsonAndErrors(document, "{\"me\": null}", errorForPath("/me"));
 		testRetrieveFieldAccessException(document, "me.name");
 	}