I have two services communicating with gRPC (one is gRPC server, and the other is gRPC client). I want to write a test for the gRPC client and want to mock the gRPC server.

I am trying to that by using wiremock-grpc-extension with a simple Java Maven project.

• I have added the proto compiler maven plugin that generates sources for the proto file
• I have configured the wiremock with the following code:

static void init() {
    WireMockServer server = new WireMockServer(
            WireMockConfiguration.wireMockConfig()
                    .port(50051)
                    .withRootDirectory("src/test/resources/wiremock")
                    .extensions(new GrpcExtensionFactory())
    );

    server.start();

    Runtime.getRuntime().addShutdownHook(new Thread(server::stop));
    System.out.println("WireMock gRPC server is running at: " + server.baseUrl());

    Helloworld.HelloWorldRequest.Builder requestBodyBuilder = Helloworld.HelloWorldRequest.newBuilder().setName("john").setSurname("doe");

    Helloworld.HelloWorldResponse.Builder responseBodyBuilder = Helloworld.HelloWorldResponse.newBuilder().setMessage("Hello JD");

    WireMockGrpcService mockService =
            new WireMockGrpcService(
                    new WireMock(server.port()),
                    HelloWorldServiceGrpc.SERVICE_NAME
            );

    mockService.stubFor(
            method("SayHello")
                    .withRequestMessage(equalToMessage(requestBodyBuilder))
                    .willReturn(message(responseBodyBuilder))
    );
}

When I run the app and check the wiremock stubs from the web console, mocking configuration seems correct (see the below image)

However, when I run the app and call the SayHello method from Postman with a gRPC request, I get “Method Not Found” error.

While I cannot call the mock server with gRPC request, I can call with an HTTP POST strangely. I am trying to mock a gRPC server not an HTTP endpoint.

I think something is wrong with my mock server configuration code but couldn’t figure out what. Any help is appreciated. Thank you in advance.