Add test for ControllerPublishVolume

[codenrhoden]

I'm opening this PR to demonstrate an error I am seeing with csi-test master. When updating the CSI external attacher/detacher, I always get a test failure for ControllerPublishVolume. In fact it hangs - took a while to track it down to this.

The reflect.DeepEqual that gomock performs to check for object equivalence is failing for the ControllerPublishVolume input. Oddly, it is only that call that fails - all the other tests pass. For simplicity, I added a test here in csi-test that demonstrates it.

When the test fails, you will see the following:

Unexpected call to *driver.MockControllerServer.ControllerPublishVolume([context.Background.WithCancel.WithCancel.WithValue(peer.peerKey{}, &peer.Peer{Addr:(*net.TCPAddr)(0xc4201b0c60), AuthInfo:credentials.AuthInfo(nil)}).WithValue(metadata.mdIncomingKey{}, metadata.MD{":authority":[]string{"127.0.0.1:51284"}, "content-type":[]string{"application/grpc"}, "user-agent":[]string{"grpc-go/1.12.2"}}).WithValue(grpc.streamKey{}, <stream: 0xc42032a000, /csi.v0.Controller/ControllerPublishVolume>) volume_id:"myname" node_id:"MyNodeID" volume_capability:<mount:<> access_mode:<mode:MULTI_NODE_MULTI_WRITER > > ]) at /Users/trhoden/go/src/github.com/kubernetes-csi/csi-test/driver/driver.mock.go:522 because:
Expected call at /Users/trhoden/go/src/github.com/kubernetes-csi/csi-test/driver/driver.mock.go:529 doesn't match the argument at index 1.
Got: volume_id:"myname" node_id:"MyNodeID" volume_capability:<mount:<> access_mode:<mode:MULTI_NODE_MULTI_WRITER > >
Want: is equal to volume_id:"myname" node_id:"MyNodeID" volume_capability:<mount:<> access_mode:<mode:MULTI_NODE_MULTI_WRITER > >
panic: MOCK TEST FATAL FAILURE

Note that the Expected and Got lines show the object is correct, but it is not being picked up that way. I've tried using different versions of gomock, grpc, regenerating the mock objects, etc., but haven't gotten around this one yet. Help is appreciated!

[codenrhoden]

I identified the underlying issue to be that since the switch to protobuf 1.1.1, one cannot use reflect.DeepEqual to test for equivalence of proto.Message. So, I added a custom matcher that instead uses proto.Equal, and things look good!

See https://groups.google.com/forum/#!topic/protobuf/N-elvFu4dFM for details on the protobuf change. This should be ready to merge now.

[lpabon]

@codenrhoden Hi, thanks for the PR. What do you suggest. Would you suggest adding this as a library to ci-test?