core: pull out reusable forwarding test, refactoring forwarding tests (#3480)

core/src/test/java/io/grpc/ForwardingChannelBuilderTest.java

@@ -19,11 +19,11 @@ package io.grpc;
 import static com.google.common.truth.Truth.assertThat;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.verify;
 
 import com.google.common.base.Defaults;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
+import java.util.Collections;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -45,20 +45,12 @@ public class ForwardingChannelBuilderTest {
   }
 
   @Test
-  public void allBuilderMethodsForwarded() throws Exception {
-    for (Method method : ManagedChannelBuilder.class.getDeclaredMethods()) {
-      if (Modifier.isStatic(method.getModifiers()) || Modifier.isPrivate(method.getModifiers())) {
-        continue;
-      }
-      Class<?>[] argTypes = method.getParameterTypes();
-      Object[] args = new Object[argTypes.length];
-      for (int i = 0; i < argTypes.length; i++) {
-        args[i] = Defaults.defaultValue(argTypes[i]);
-      }
-
-      method.invoke(testChannelBuilder, args);
-      method.invoke(verify(mockDelegate), args);
-    }
+  public void allMethodsForwarded() throws Exception {
+    ForwardingTestUtil.testMethodsForwarded(
+        ManagedChannelBuilder.class,
+        mockDelegate,
+        testChannelBuilder,
+        Collections.<Method>emptyList());
   }
 
   @Test

core/src/test/java/io/grpc/ForwardingServerCallListenerTest.java

@@ -19,6 +19,8 @@ package io.grpc;
 import static org.mockito.Mockito.verify;
 
 import io.grpc.ForwardingServerCallListener.SimpleForwardingServerCallListener;
+import java.lang.reflect.Method;
+import java.util.Collections;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -26,51 +28,32 @@ import org.junit.runners.JUnit4;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
+/**
+ * Unit tests for {@link ForwardingServerCallListener}.
+ */
 @RunWith(JUnit4.class)
 public class ForwardingServerCallListenerTest {
 
-  @Mock private ServerCall.Listener<Void> serverCallListener;
-  private ForwardingServerCallListener<Void> forwarder;
+  @Mock private ServerCall.Listener<Integer> serverCallListener;
+  private ForwardingServerCallListener<Integer> forwarder;
 
   @Before
   public void setUp() {
     MockitoAnnotations.initMocks(this);
-    forwarder = new SimpleForwardingServerCallListener<Void>(serverCallListener) {};
+    forwarder = new SimpleForwardingServerCallListener<Integer>(serverCallListener) {};
+  }
+
+  @Test
+  public void allMethodsForwarded() throws Exception {
+    ForwardingTestUtil.testMethodsForwarded(
+        ServerCall.Listener.class, serverCallListener, forwarder, Collections.<Method>emptyList());
   }
 
   @Test
   public void onMessage() {
-    forwarder.onMessage(null);
+    forwarder.onMessage(12345);
 
-    verify(serverCallListener).onMessage(null);
-  }
-
-  @Test
-  public void onHalfClose() {
-    forwarder.onHalfClose();
-
-    verify(serverCallListener).onHalfClose();
-  }
-
-  @Test
-  public void onCancel() {
-    forwarder.onCancel();
-
-    verify(serverCallListener).onCancel();
-  }
-
-  @Test
-  public void onComplete() {
-    forwarder.onComplete();
-
-    verify(serverCallListener).onComplete();
-  }
-
-  @Test
-  public void onReady() {
-    forwarder.onReady();
-
-    verify(serverCallListener).onReady();
+    verify(serverCallListener).onMessage(12345);
   }
 }
 

core/src/test/java/io/grpc/ForwardingTestUtil.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2017, gRPC Authors All rights reserved.
+ *
+ * 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
+ * limitations under the License.
+ */
+
+package io.grpc;
+
+import static junit.framework.TestCase.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.mockingDetails;
+import static org.mockito.Mockito.verify;
+
+import com.google.common.base.Defaults;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.Collection;
+
+/**
+ * A util class to help test forwarding classes.
+ */
+public final class ForwardingTestUtil {
+  /**
+   * Use reflection to perform a basic sanity test. The forwarding class should forward all public
+   * methods to the delegate, except for those in skippedMethods.
+   * This does NOT verify that arguments or return values are forwarded properly. It only alerts
+   * the developer if a forward method is missing.
+   *
+   * @param delegateClass The class whose methods should be forwarded.
+   * @param mockDelegate The mockito mock of the delegate class.
+   * @param forwarder The forwarder object that forwards to the mockDelegate.
+   * @param skippedMethods A collection of methods that are skipped by the test.
+   */
+  public static <T> void testMethodsForwarded(
+      Class<T> delegateClass,
+      T mockDelegate,
+      T forwarder,
+      Collection<Method> skippedMethods) throws Exception {
+    assertTrue(mockingDetails(mockDelegate).isMock());
+    assertFalse(mockingDetails(forwarder).isMock());
+
+    for (Method method : delegateClass.getDeclaredMethods()) {
+      if (Modifier.isStatic(method.getModifiers())
+          || Modifier.isPrivate(method.getModifiers())
+          || skippedMethods.contains(method)) {
+        continue;
+      }
+      Class<?>[] argTypes = method.getParameterTypes();
+      Object[] args = new Object[argTypes.length];
+      for (int i = 0; i < argTypes.length; i++) {
+        args[i] = Defaults.defaultValue(argTypes[i]);
+      }
+      method.invoke(forwarder, args);
+      try {
+        method.invoke(verify(mockDelegate), args);
+      } catch (InvocationTargetException e) {
+        throw new AssertionError(String.format("Method was not forwarded: %s", method));
+      }
+    }
+  }
+}

core/src/test/java/io/grpc/internal/ForwardingNameResolverTest.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2017, gRPC Authors All rights reserved.
+ *
+ * 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
+ * limitations under the License.
+ */
+
+package io.grpc.internal;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import io.grpc.Attributes;
+import io.grpc.EquivalentAddressGroup;
+import io.grpc.ForwardingTestUtil;
+import io.grpc.NameResolver;
+import io.grpc.Status;
+import java.lang.reflect.Method;
+import java.util.Collections;
+import java.util.List;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/**
+ * Unit tests for {@link ForwardingNameResolver}.
+ */
+@RunWith(JUnit4.class)
+public class ForwardingNameResolverTest {
+  private final NameResolver delegate = mock(NameResolver.class);
+  private final NameResolver forwarder = new ForwardingNameResolver(delegate) {
+  };
+
+  @Test
+  public void allMethodsForwarded() throws Exception {
+    ForwardingTestUtil.testMethodsForwarded(
+        NameResolver.class,
+        delegate,
+        forwarder,
+        Collections.<Method>emptyList());
+  }
+
+  @Test
+  public void getServiceAuthority() {
+    String auth = "example.com";
+    when(delegate.getServiceAuthority()).thenReturn(auth);
+
+    assertEquals(auth, forwarder.getServiceAuthority());
+  }
+
+  @Test
+  public void start() {
+    NameResolver.Listener listener = new NameResolver.Listener() {
+      @Override
+      public void onAddresses(List<EquivalentAddressGroup> servers, Attributes attributes) { }
+
+      @Override
+      public void onError(Status error) { }
+    };
+
+    forwarder.start(listener);
+    verify(delegate).start(listener);
+  }
+}

core/src/test/java/io/grpc/internal/ForwardingReadableBufferTest.java

@@ -17,10 +17,16 @@
 package io.grpc.internal;
 
 import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
+import io.grpc.ForwardingTestUtil;
 import java.io.IOException;
+import java.io.OutputStream;
+import java.lang.reflect.Method;
+import java.nio.ByteBuffer;
+import java.util.Collections;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -43,6 +49,15 @@ public class ForwardingReadableBufferTest {
     buffer = new ForwardingReadableBuffer(delegate) {};
   }
 
+  @Test
+  public void allMethodsForwarded() throws Exception {
+    ForwardingTestUtil.testMethodsForwarded(
+        ReadableBuffer.class,
+        delegate,
+        buffer,
+        Collections.<Method>emptyList());
+  }
+
   @Test
   public void readableBytes() {
     when(delegate.readableBytes()).thenReturn(1);
@@ -73,23 +88,26 @@ public class ForwardingReadableBufferTest {
 
   @Test
   public void readBytes() {
-    buffer.readBytes(null, 1, 2);
+    byte[] dest = new byte[1];
+    buffer.readBytes(dest, 1, 2);
 
-    verify(delegate).readBytes(null, 1, 2);
+    verify(delegate).readBytes(dest, 1, 2);
   }
 
   @Test
   public void readBytes_overload1() {
-    buffer.readBytes(null);
+    ByteBuffer dest = mock(ByteBuffer.class);
+    buffer.readBytes(dest);
 
-    verify(delegate).readBytes(null);
+    verify(delegate).readBytes(dest);
   }
 
   @Test
   public void readBytes_overload2() throws IOException {
-    buffer.readBytes(null, 1);
+    OutputStream dest = mock(OutputStream.class);
+    buffer.readBytes(dest, 1);
 
-    verify(delegate).readBytes(null, 1);
+    verify(delegate).readBytes(dest, 1);
   }
 
   @Test
@@ -108,9 +126,10 @@ public class ForwardingReadableBufferTest {
 
   @Test
   public void array() {
-    when(delegate.array()).thenReturn(null);
+    byte[] array = new byte[1];
+    when(delegate.array()).thenReturn(array);
 
-    assertEquals(null, buffer.array());
+    assertEquals(array, buffer.array());
   }
 
   @Test