all: Prefer mock+delegatesTo() over Mockito.spy()

Spies are really magical and easily produce unexpected results. Using them in
tests can easily yield tests that don't do what you think they do. Delegation
is much safer when possible.

Delegation doesn't work when methods `return true`, final methods, and with
restricted visibility, though. So CensusModulesTest and
MaxConnectionIdleManagerTest are left as-is.

2 files changed, 3 insertions, 4 deletions

diff --git a/netty/src/test/java/io/grpc/netty/NettyHandlerTestBase.java b/netty/src/test/java/io/grpc/netty/NettyHandlerTestBase.java
index 70206b6ba..9c938773a 100644
--- a/netty/src/test/java/io/grpc/netty/NettyHandlerTestBase.java
+++ b/netty/src/test/java/io/grpc/netty/NettyHandlerTestBase.java
@@ -25,7 +25,6 @@ import static org.mockito.Matchers.anyLong;
 import static org.mockito.Mockito.atLeastOnce;
 import static org.mockito.Mockito.doAnswer;
 import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
@@ -114,7 +113,7 @@ public abstract class NettyHandlerTestBase<T extends Http2ConnectionHandler> {
    */
   protected final void initChannel(Http2HeadersDecoder headersDecoder) throws Exception {
     content = Unpooled.copiedBuffer("hello world", UTF_8);
-    frameWriter = spy(new DefaultHttp2FrameWriter());
+    frameWriter = mock(Http2FrameWriter.class, delegatesTo(new DefaultHttp2FrameWriter()));
     frameReader = new DefaultHttp2FrameReader(headersDecoder);
 
     handler = newHandler();
diff --git a/netty/src/test/java/io/grpc/netty/NettyServerHandlerTest.java b/netty/src/test/java/io/grpc/netty/NettyServerHandlerTest.java
index 5303c837f..9a2f84b38 100644
--- a/netty/src/test/java/io/grpc/netty/NettyServerHandlerTest.java
+++ b/netty/src/test/java/io/grpc/netty/NettyServerHandlerTest.java
@@ -45,7 +45,6 @@ import static org.mockito.Mockito.doAnswer;
 import static org.mockito.Mockito.doThrow;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
-import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
@@ -121,7 +120,8 @@ public class NettyServerHandlerTest extends NettyHandlerTestBase<NettyServerHand
   @Mock
   private ServerStreamTracer.Factory streamTracerFactory;
 
-  private final ServerTransportListener transportListener = spy(new ServerTransportListenerImpl());
+  private final ServerTransportListener transportListener =
+      mock(ServerTransportListener.class, delegatesTo(new ServerTransportListenerImpl()));
   private final TestServerStreamTracer streamTracer = new TestServerStreamTracer();
 
   private NettyServerStream stream;