examples/helloworld/mock_helloworld/hw_mock_test.go

package mock_helloworld_test

import (
	"fmt"
	"testing"

	"github.com/golang/mock/gomock"
	"github.com/golang/protobuf/proto"
	"golang.org/x/net/context"
	helloworld "google.golang.org/grpc/examples/helloworld/helloworld"
	hwmock "google.golang.org/grpc/examples/helloworld/mock_helloworld"
)

// rpcMsg implements the gomock.Matcher interface
type rpcMsg struct {
	msg proto.Message
}

func (r *rpcMsg) Matches(msg interface{}) bool {
	m, ok := msg.(proto.Message)
	if !ok {
		return false
	}
	return proto.Equal(m, r.msg)
}

func (r *rpcMsg) String() string {
	return fmt.Sprintf("is %s", r.msg)
}

func TestSayHello(t *testing.T) {
	ctrl := gomock.NewController(t)
	defer ctrl.Finish()
	mockGreeterClient := hwmock.NewMockGreeterClient(ctrl)
	req := &helloworld.HelloRequest{Name: "unit_test"}
	mockGreeterClient.EXPECT().SayHello(
		gomock.Any(),
		&rpcMsg{msg: req},
	).Return(&helloworld.HelloReply{Message: "Mocked Interface"}, nil)
	testSayHello(t, mockGreeterClient)
}

func testSayHello(t *testing.T, client helloworld.GreeterClient) {
	r, err := client.SayHello(context.Background(), &helloworld.HelloRequest{Name: "unit_test"})
	if err != nil || r.Message != "Mocked Interface" {
		t.Errorf("mocking failed")
	}
	t.Log("Reply : ", r.Message)
}