diff --git a/core/src/main/java/com/google/net/stubby/proto/DeferredProtoInputStream.java b/core/src/main/java/com/google/net/stubby/proto/DeferredProtoInputStream.java
index ba135be355..657052e7ed 100644
--- a/core/src/main/java/com/google/net/stubby/proto/DeferredProtoInputStream.java
+++ b/core/src/main/java/com/google/net/stubby/proto/DeferredProtoInputStream.java
@@ -64,6 +64,11 @@ public class DeferredProtoInputStream extends DeferredInputStream<MessageLite> {
   public int read(byte[] b, int off, int len) throws IOException {
     if (message != null) {
       int size = message.getSerializedSize();
+      if (size == 0) {
+        message = null;
+        partial = null;
+        return -1;
+      }
       if (len >= size) {
         // This is the only case that is zero-copy.
         CodedOutputStream stream = CodedOutputStream.newInstance(b, off, size);
diff --git a/testing/src/main/java/com/google/net/stubby/testing/InProcessUtils.java b/testing/src/main/java/com/google/net/stubby/testing/InProcessUtils.java
new file mode 100644
index 0000000000..d6636a49dc
--- /dev/null
+++ b/testing/src/main/java/com/google/net/stubby/testing/InProcessUtils.java
@@ -0,0 +1,227 @@
+package com.google.net.stubby.testing;
+
+import com.google.common.util.concurrent.AbstractService;
+import com.google.net.stubby.HandlerRegistry;
+import com.google.net.stubby.Metadata;
+import com.google.net.stubby.MethodDescriptor;
+import com.google.net.stubby.SerializingExecutor;
+import com.google.net.stubby.ServerCall;
+import com.google.net.stubby.ServerMethodDefinition;
+import com.google.net.stubby.Status;
+import com.google.net.stubby.newtransport.ClientStream;
+import com.google.net.stubby.newtransport.ClientStreamListener;
+import com.google.net.stubby.newtransport.ClientTransport;
+import com.google.net.stubby.newtransport.ClientTransportFactory;
+import com.google.net.stubby.newtransport.StreamState;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import javax.annotation.Nullable;
+
+/**
+ * Utility functions for binding clients to in-process services.
+ */
+public class InProcessUtils {
+
+  /**
+   * Create a {@link ClientTransportFactory} connected to the given {@link com.google.net.stubby.HandlerRegistry}
+   */
+  public static ClientTransportFactory adaptHandlerRegistry(HandlerRegistry handlers,
+                                                            ExecutorService executor) {
+    final ClientTransport transport = new InProcessClientTransport(handlers, executor);
+    return new ClientTransportFactory() {
+      @Override
+      public ClientTransport newClientTransport() {
+        return transport;
+      }
+    };
+  }
+
+  private InProcessUtils() {
+  }
+
+  /**
+   * Implementation of ClientTransport that delegates to a {@link com.google.net.stubby.ServerCall.Listener}
+   */
+  private static class InProcessClientTransport extends AbstractService
+      implements ClientTransport {
+    private final HandlerRegistry handlers;
+
+    private final ExecutorService executor;
+
+    public InProcessClientTransport(HandlerRegistry handlers, ExecutorService executor) {
+      this.handlers = handlers;
+      this.executor = executor;
+    }
+
+    @Override
+    protected void doStart() {
+      notifyStarted();
+    }
+
+    @Override
+    public void doStop() {
+      notifyStopped();
+    }
+
+    @Override
+    public ClientStream newStream(MethodDescriptor<?, ?> method,
+                                  final Metadata.Headers headers,
+                                  final ClientStreamListener clientListener) {
+      // Separate FIFO executor queues for work on the client and server
+      final SerializingExecutor serverWorkQueue = new SerializingExecutor(executor);
+      final SerializingExecutor clientWorkQueue = new SerializingExecutor(executor);
+
+      final HandlerRegistry.Method resolvedMethod = handlers.lookupMethod("/" + method.getName());
+      if (resolvedMethod == null) {
+        // Threading?
+        clientWorkQueue.execute(new Runnable() {
+          @Override
+          public void run() {
+            clientListener.closed(Status.UNIMPLEMENTED, new Metadata.Trailers());
+          }
+        });
+        return new NoOpClientStream();
+      }
+
+      final ServerMethodDefinition serverMethod = resolvedMethod.getMethodDefinition();
+      final AtomicBoolean cancelled = new AtomicBoolean();
+
+      // Implementation of ServerCall which delegates to the client listener.
+      final ServerCall serverCall = new ServerCall() {
+        @Override
+        public void close(final Status status, final Metadata.Trailers trailers) {
+          clientWorkQueue.execute(new Runnable() {
+            @Override
+            public void run() {
+              clientListener.closed(status, trailers);
+            }
+          });
+
+        }
+
+        @Override
+        public void sendPayload(final Object payload) {
+          clientWorkQueue.execute(new Runnable() {
+            @Override
+            public void run() {
+              try {
+                // TODO(user): Consider adapting at the Channel layer on the client
+                // so we avoid serialization costs.
+                InputStream message = serverMethod.streamResponse(payload);
+                clientListener.messageRead(message, message.available());
+              } catch (IOException ioe) {
+                close(Status.fromThrowable(ioe), new Metadata.Trailers());
+              }
+            }
+          });
+        }
+
+        @Override
+        public boolean isCancelled() {
+          return cancelled.get();
+        }
+      };
+
+      // Get the listener from the service implementation
+      final ServerCall.Listener serverListener =
+          serverMethod.getServerCallHandler().startCall(method.getName(),
+              serverCall);
+
+      // Send headers
+      serverWorkQueue.execute(new Runnable() {
+        @Override
+        public void run() {
+          serverListener.headersRead(headers);
+        }
+      });
+
+      // Return implementation of ClientStream which delegates to the server listener.
+      return new ClientStream() {
+
+        StreamState state = StreamState.OPEN;
+
+        @Override
+        public void cancel() {
+          cancelled.set(true);
+          state = StreamState.CLOSED;
+          serverWorkQueue.execute(new Runnable() {
+            @Override
+            public void run() {
+              serverListener.onCancel();
+            }
+          });
+        }
+
+        @Override
+        public void halfClose() {
+          state = StreamState.WRITE_ONLY;
+          serverWorkQueue.execute(new Runnable() {
+            @Override
+            public void run() {
+              serverListener.onHalfClose();
+            }
+          });
+        }
+
+        @Override
+        public StreamState state() {
+          return state;
+        }
+
+        @Override
+        public void writeMessage(final InputStream message, int length,
+                                 @Nullable final Runnable accepted) {
+          serverWorkQueue.execute(new Runnable() {
+            @Override
+            public void run() {
+              try {
+                serverListener.onPayload(serverMethod.parseRequest(message));
+              } catch (RuntimeException re) {
+                serverCall.close(Status.fromThrowable(re), new Metadata.Trailers());
+              } finally {
+                if (accepted != null) {
+                  accepted.run();
+                }
+              }
+            }
+          });
+        }
+
+        @Override
+        public void flush() {
+          // No-op
+        }
+      };
+    }
+
+    // Simple No-Op implementation of ClientStream
+    private static class NoOpClientStream implements ClientStream {
+      @Override
+      public void cancel() {
+        // No-op
+      }
+
+      @Override
+      public void halfClose() {
+        // No-op
+      }
+
+      @Override
+      public StreamState state() {
+        return StreamState.CLOSED;
+      }
+
+      @Override
+      public void writeMessage(InputStream message, int length, @Nullable Runnable accepted) {
+      }
+
+      @Override
+      public void flush() {
+      }
+    }
+  }
+}