grpc-test

Prompt file imported from ADASK-B/gRPC.Agent.Template (.github/prompts/grpc-test.prompt.md). Copyright stays with the author.

Generate integration tests for gRPC services:

Test Project Setup

Required NuGet packages:

• Microsoft.AspNetCore.Mvc.Testing
• Grpc.Net.Client
• Grpc.Tools (for proto compilation)
• A test framework (xUnit, NUnit, or MSTest)

Reference the same .proto files as the server project with GrpcServices="Client" or GrpcServices="Both".

Test Infrastructure

public class GrpcTestFixture<TStartup> : IDisposable where TStartup : class
{
    private readonly WebApplicationFactory<TStartup> _factory;
    public GrpcChannel Channel { get; }

    public GrpcTestFixture()
    {
        _factory = new WebApplicationFactory<TStartup>();
        var client = _factory.CreateDefaultClient(new ResponseVersionHandler());
        Channel = GrpcChannel.ForAddress(client.BaseAddress!, new GrpcChannelOptions
        {
            HttpClient = client
        });
    }

    public void Dispose()
    {
        Channel.Dispose();
        _factory.Dispose();
    }
}

// Required to set HTTP/2 for the test client
public class ResponseVersionHandler : DelegatingHandler
{
    protected override async Task<HttpResponseMessage> SendAsync(
        HttpRequestMessage request, CancellationToken ct)
    {
        request.Version = new Version(2, 0);
        var response = await base.SendAsync(request, ct);
        response.Version = request.Version;
        return response;
    }
}

Test Patterns

Unary RPC Test

[Fact]
public async Task GetItem_ValidId_ReturnsItem()
{
    var client = new MyService.MyServiceClient(Channel);

    var reply = await client.GetItemAsync(new GetItemRequest { Id = "123" });

    Assert.Equal("123", reply.Item.Id);
}

Error Handling Test

[Fact]
public async Task GetItem_EmptyId_ThrowsRpcException()
{
    var client = new MyService.MyServiceClient(Channel);

    var ex = await Assert.ThrowsAsync<RpcException>(
        () => client.GetItemAsync(new GetItemRequest { Id = "" }));

    Assert.Equal(StatusCode.InvalidArgument, ex.StatusCode);
}

Streaming RPC Test

[Fact]
public async Task ServerStream_ReturnsAllMessages()
{
    var client = new MyService.MyServiceClient(Channel);
    var messages = new List<ResponseMessage>();

    using var call = client.ServerStreamMethod(new Request());
    await foreach (var msg in call.ResponseStream.ReadAllAsync())
    {
        messages.Add(msg);
    }

    Assert.NotEmpty(messages);
}

Guidelines

• Test both success and error paths
• Verify correct gRPC status codes for error cases
• Test deadline/cancellation behavior
• Use unique test data to avoid conflicts
• Mock external dependencies using DI service overrides