MethodDataFetcher should not swallow exceptions. Fixes Enigmatis#4

Author: yrashk

src/main/java/graphql/annotations/MethodDataFetcher.java

@@ -47,7 +47,7 @@ public Object get(DataFetchingEnvironment environment) {
             }
             return method.invoke(environment.getSource(), args.toArray());
         } catch (IllegalAccessException | InvocationTargetException e) {
-            return null;
+            throw new RuntimeException(e);
         }
     }
 }

src/test/java/graphql/annotations/MethodDataFetcherTest.java

@@ -0,0 +1,41 @@
+/**
+ * Copyright 2016 Yurii Rashkovskii
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ */
+package graphql.annotations;
+
+import graphql.schema.DataFetchingEnvironment;
+import org.testng.annotations.Test;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+
+import static org.testng.Assert.*;
+
+public class MethodDataFetcherTest {
+
+    public class TestException extends Exception {};
+
+    public String method() throws TestException {
+        throw new TestException();
+    }
+    @Test(expectedExceptions = RuntimeException.class)
+    public void exceptionRethrowing() {
+        try {
+            MethodDataFetcher methodDataFetcher = new MethodDataFetcher(getClass().getMethod("method"));
+            methodDataFetcher.get(new DataFetchingEnvironment(this, new HashMap<>(), null, new ArrayList<>(), null, null, null));
+        } catch (NoSuchMethodException e) {
+            e.printStackTrace();
+        }
+    }
+}