WireMock.Net.Google.Protobuf

Statically typed gRPC mocking for WireMock.Net using generated Google.Protobuf contracts.

Request.Create()
    .WithBodyAsGoogleProtobuf(new HelloRequest { Name = "Stepan" });

Response.Create()
    .WithBodyAsGoogleProtobuf(
        new HelloReply { Message = "Hello, Stepan!" });

No ProtoDefinition, message type strings, JSON conversion, or manually constructed binary payloads.

Why?

The standard WireMock.Net protobuf integration requires loading .proto definitions and referring to protobuf message types separately from your generated C# contracts.

This package uses the generated IMessage<T> types you already have to write less configuration and do no duplicated schema setup:

• compile-time type safety;
• native Google.Protobuf serialization;
• exact-message and predicate request matching;

When a contract changes, outdated mocks stop compiling instead of failing at runtime.

Installation

dotnet add package WireMock.Grpc.Protobuf

The package targets .NET 8

Message Matching

Assuming you have some greet.proto file that generates HelloRequest, HelloReply, and Greeter.GreeterClient for instance:

syntax = "proto3";

option csharp_namespace = "Greeting.Contracts";

package greet;

service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply);
}

message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}

And assuming you also have the required packages added with protobuf compilation settings to your test project:

<Project Sdk="Microsoft.NET.Sdk">
    <ItemGroup>
        <PackageReference Include="WireMock.Net" Version="2.13.0" />
        <PackageReference Include="WireMock.Grpc.Protobuf" Version="1.0.0" />
        <PackageReference Include="Grpc.Net.Client" Version="2.80.0" />
        <PackageReference Include="Grpc.Core" Version="2.46.6"/>
        <PackageReference Include="Grpc.Tools" Version="2.82.0">
            <PrivateAssets>all</PrivateAssets>
            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
        </PackageReference>
    </ItemGroup>

    <ItemGroup>
        <Protobuf Include=".\test.proto" GrpcServices="Client" />
    </ItemGroup>
</Project>

Start WireMock.Net with HTTP/2 enabled and configure the expected request and response using the WithBodyAsGoogleProtobuf extension methods:

using Greeting.Contracts;
using Grpc.Net.Client;
using WireMock.Net.Google.Protobuf.Request;
using WireMock.Net.Google.Protobuf.Response;
using WireMock.RequestBuilders;
using WireMock.ResponseBuilders;
using WireMock.Server;
using WireMock.Settings;

using var server = WireMockServer.Start(
    new WireMockServerSettings
    {
        UseHttp2 = true
    });

var request = new HelloRequest
{
    Name = "Stepan"
};

var expectedResponse = new HelloReply
{
    Message = "Hello, Stepan!"
};

server
    .Given(
        Request.Create()
            .UsingPost()
            .WithHttpVersion("2")
            .WithPath("/greet.Greeter/SayHello")
            .WithBodyAsGoogleProtobuf(request))
    .RespondWith(
        Response.Create()
            .WithHeader("Content-Type", "application/grpc")
            .WithTrailingHeader("grpc-status", "0")
            .WithBodyAsGoogleProtobuf(expectedResponse));

using var channel = GrpcChannel.ForAddress(server.Url!);
var client = new Greeter.GreeterClient(channel);

var actualResponse = await client.SayHelloAsync(request);

Assert.Equal(expectedResponse, actualResponse);

Predicate Matching

Match only the fields relevant to your test:

Request.Create()
    .WithBodyAsGoogleProtobuf<HelloRequest>(
        request =>
            request.Name.StartsWith("Step") &&
            request.Name.Length >= 5);

This keeps request matching strongly typed without comparing the entire protobuf message.

Important

Do not call WithTransformer() after WithBodyAsGoogleProtobuf(). The response is already a binary gRPC frame, and text transformation may corrupt it.

WireMock.Net must also run with HTTP/2 enabled:

new WireMockServerSettings
{
    UseHttp2 = true
};

License

Distributed under the MIT License.