Github user tillrohrmann commented on a diff in the pull request:
https://github.com/apache/flink/pull/5239#discussion_r165325793
--- Diff:
flink-core/src/test/java/org/apache/flink/util/MethodForwardingTestUtil.java ---
@@ -0,0 +1,146 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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
+ * limitations under the License.
+ */
+
+package org.apache.flink.util;
+
+import org.mockito.Mockito;
+
+import java.lang.reflect.Array;
+import java.lang.reflect.Method;
+import java.util.Collections;
+import java.util.Set;
+import java.util.function.Function;
+
+import static org.junit.Assert.fail;
+import static org.mockito.Mockito.reset;
+import static org.mockito.Mockito.spy;
+
+/**
+ * Helper class with a method that attempt to automatically test method
forwarding between a delegate and a wrapper.
+ */
+public class MethodForwardingTestUtil {
+
+ /**
+ * This is a best effort automatic test for method forwarding between a
delegate and its wrapper, where the wrapper
+ * class is a subtype of the delegate. This ignores methods that are
inherited from Object.
+ *
+ * @param delegateClass the class for the delegate.
+ * @param wrapperFactory factory that produces a wrapper from a
delegate.
+ * @param <D> type of the delegate
+ * @param <W> type of the wrapper
+ */
+ public static <D, W> void testMethodForwarding(
+ Class<D> delegateClass,
+ Function<D, W> wrapperFactory) {
+ testMethodForwarding(delegateClass, wrapperFactory,
Collections.emptySet());
+ }
+
+ /**
+ * This is a best effort automatic test for method forwarding between a
delegate and its wrapper, where the wrapper
+ * class is a subtype of the delegate. Methods can be remapped in case
that the implementation does not call the
+ * original method. Remapping to null skips the method. This ignores
methods that are inherited from Object.
+ *
+ * @param delegateClass the class for the delegate.
+ * @param wrapperFactory factory that produces a wrapper from a
delegate.
+ * @param skipMethodSet set of methods to ignore.
+ * @param <D> type of the delegate
+ * @param <W> type of the wrapper
+ */
+ public static <D, W> void testMethodForwarding(
+ Class<D> delegateClass,
+ Function<D, W> wrapperFactory,
+ Set<Method> skipMethodSet) {
+
+ Preconditions.checkNotNull(delegateClass);
+ Preconditions.checkNotNull(wrapperFactory);
+ Preconditions.checkNotNull(skipMethodSet);
+
+ D delegate = spy(delegateClass);
+ W wrapper = wrapperFactory.apply(delegate);
+
+ // ensure that wrapper is a subtype of delegate
+
Preconditions.checkArgument(delegateClass.isAssignableFrom(wrapper.getClass()));
+
+ for (Method delegateMethod : delegateClass.getMethods()) {
+
+ if (checkSkipMethodForwardCheck(delegateMethod,
skipMethodSet)) {
+ continue;
+ }
+
+ try {
+ // find the correct method to substitute the
bridge for erased generic types.
+ // if this doesn't work, the user need to
exclude the method and write an additional test.
+ Method wrapperMethod =
wrapper.getClass().getDeclaredMethod(
+ delegateMethod.getName(),
+ delegateMethod.getParameterTypes());
+
+ // things get a bit fuzzy here, best effort to
find a match but this might end up with a wrong method.
+ if (wrapperMethod.isBridge()) {
+ for (Method method :
wrapper.getClass().getDeclaredMethods()) {
+ if (!method.isBridge()
+ &&
method.getName().equals(wrapperMethod.getName())
+ &&
method.getParameterCount() == wrapperMethod.getParameterCount()) {
+ wrapperMethod = method;
+ break;
+ }
+ }
+ }
+
+ Class<?>[] parameterTypes =
wrapperMethod.getParameterTypes();
+ Object[] arguments = new
Object[parameterTypes.length];
+ for (int j = 0; j < arguments.length; j++) {
+ Class<?> parameterType =
parameterTypes[j];
+ if (parameterType.isArray()) {
+ arguments[j] =
Array.newInstance(parameterType.getComponentType(), 0);
+ } else if (parameterType.isPrimitive())
{
+ arguments[j] = 0;
--- End diff --
Why is a primitive always of type `int`?
---
