How do you write unit and integration tests for gRPC services in Go?

import (
    "google.golang.org/grpc"
    "google.golang.org/grpc/test/bufconn"
)

const bufSize = 1024 * 1024

// Setup: start server in-process with bufconn
func setupTestServer(t *testing.T, repo UserRepository) pb.UserServiceClient {
    t.Helper()

    lis := bufconn.Listen(bufSize)
    grpcServer := grpc.NewServer()
    pb.RegisterUserServiceServer(grpcServer,
        &userServiceServer{repo: repo})

    go func() {
        if err := grpcServer.Serve(lis); err != nil {
            t.Logf("server error: %v", err)
        }
    }()
    t.Cleanup(func() { grpcServer.GracefulStop() })

    // Dial using the in-memory buffer
    conn, err := grpc.NewClient(
        "passthrough://bufnet",
        grpc.WithContextDialer(func(ctx context.Context, _ string) (net.Conn, error) {
            return lis.DialContext(ctx)
        }),
        grpc.WithTransportCredentials(insecure.NewCredentials()),
    )
    if err != nil { t.Fatalf("dial: %v", err) }
    t.Cleanup(func() { conn.Close() })

    return pb.NewUserServiceClient(conn)
}

// Table-driven gRPC test
func TestGetUser(t *testing.T) {
    fakeRepo := &fakeUserRepo{
        users: map[int]*User{1: {ID: 1, Name: "Alice"}},
    }
    client := setupTestServer(t, fakeRepo)

    tests := []struct {
        name     string
        id       int64
        wantName string
        wantCode codes.Code
    }{
        {"existing user", 1, "Alice", codes.OK},
        {"missing user", 99, "", codes.NotFound},
        {"invalid id",   0, "", codes.InvalidArgument},
    }

    for _, tt := range tests {
        t.Run(tt.name, func(t *testing.T) {
            resp, err := client.GetUser(context.Background(),
                &pb.GetUserRequest{Id: tt.id})

            if code := status.Code(err); code != tt.wantCode {
                t.Errorf("got code %v, want %v", code, tt.wantCode)
            }
            if tt.wantName != "" && resp.Name != tt.wantName {
                t.Errorf("got name %q, want %q", resp.Name, tt.wantName)
            }
        })
    }
}