stub: Improve ClientCall test to fail more obviously

If the timoutout expires, the test will almost certainly fail now due to
responses not matching expected responses, but it isn't as obvious why
the test fails. Swapping to ArrayList prints the entire list when they
don't match, which also makes it easier to diagnose.

This is, in part, to help diagnose #1932

stub/src/test/java/io/grpc/stub/ClientCallsTest.java

@@ -31,9 +31,9 @@
 
 package io.grpc.stub;
 
-import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.times;
@@ -62,7 +62,10 @@ import org.mockito.ArgumentCaptor;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Iterator;
+import java.util.List;
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutionException;
@@ -292,12 +295,11 @@ public class ClientCallsTest {
     final ClientCall<Integer, Integer> clientCall = channel.newCall(STREAMING_METHOD,
         CallOptions.DEFAULT);
     final CountDownLatch latch = new CountDownLatch(1);
-    final int[] receivedMessages = new int[6];
+    final List<Integer> receivedMessages = new ArrayList<Integer>(6);
     semaphore.acquire();
 
     ClientResponseObserver<Integer, Integer> responseObserver =
         new ClientResponseObserver<Integer, Integer>() {
-          int index;
           @Override
           public void beforeStart(final ClientCallStreamObserver<Integer> requestStream) {
             requestStream.disableAutoInboundFlowControl();
@@ -305,7 +307,7 @@ public class ClientCallsTest {
 
           @Override
           public void onNext(Integer value) {
-            receivedMessages[index++] = value;
+            receivedMessages.add(value);
           }
 
           @Override
@@ -326,18 +328,17 @@ public class ClientCallsTest {
     semaphore.acquire();
     integerStreamObserver.request(3);
     integerStreamObserver.onCompleted();
-    latch.await(5, TimeUnit.SECONDS);
+    assertTrue(latch.await(5, TimeUnit.SECONDS));
     // Very that number of messages produced in each onReady handler call matches the number
     // requested by the client. Note that ClientCalls.asyncBidiStreamingCall will request(1)
-
+    assertEquals(Arrays.asList(0, 1, 1, 2, 2, 2), receivedMessages);
-    assertArrayEquals(new int[]{0, 1, 1, 2, 2, 2}, receivedMessages);
   }
 
   @Test
   public void inprocessTransportOutboundFlowControl() throws Exception {
     final CountDownLatch latch = new CountDownLatch(1);
     final Semaphore semaphore = new Semaphore(1);
-    final int[] receivedMessages = new int[6];
+    final List<Integer> receivedMessages = new ArrayList<Integer>(6);
     ServerServiceDefinition service = ServerServiceDefinition.builder(
         new ServiceDescriptor("some", STREAMING_METHOD))
         .addMethod(STREAMING_METHOD, ServerCalls.asyncBidiStreamingCall(
@@ -362,10 +363,9 @@ public class ClientCallsTest {
                   }
                 }).start();
                 return new ServerCalls.NoopStreamObserver<Integer>() {
-                  int index;
                   @Override
                   public void onNext(Integer value) {
-                    receivedMessages[index++] = value;
+                    receivedMessages.add(value);
                   }
 
                   @Override
@@ -418,10 +418,10 @@ public class ClientCallsTest {
         };
 
     ClientCalls.asyncBidiStreamingCall(clientCall, responseObserver);
-    latch.await(5, TimeUnit.SECONDS);
+    assertTrue(latch.await(5, TimeUnit.SECONDS));
     // Very that number of messages produced in each onReady handler call matches the number
     // requested by the client.
-    assertArrayEquals(new int[]{0, 1, 1, 2, 2, 2}, receivedMessages);
+    assertEquals(Arrays.asList(0, 1, 1, 2, 2, 2), receivedMessages);
   }
 
   @Test