grpcstub

grpcstub provides gRPC server and client conn ( *grpc.ClientConn ) for stubbing, for testing in Go.

There is an HTTP version stubbing tool with the same design concept, httpstub.

Usage

package myapp

import (
	"io"
	"net/http"
	"testing"

	"github.com/k1LoW/grpcstub"
	"github.com/k1LoW/myapp/protobuf/gen/go/routeguide"
)

func TestClient(t *testing.T) {
	ctx := context.Background()
	ts := grpcstub.NewServer(t, "path/to/protobuf")
	t.Cleanup(func() {
		ts.Close()
	})
	ts.Method("GetFeature").Response(&routeguite.Feature{
		Name: "hello",
		Location: &routeguide.Point{
			Latitude:  10,
			Longitude: 13,
		},
	})
	// OR
	// ts.Method("GetFeature").Response(map[string]any{"name": "hello", "location": map[string]any{"latitude": 10, "longitude": 13}})

	client := routeguide.NewRouteGuideClient(ts.Conn())
	if _, err := client.GetFeature(ctx, &routeguide.Point{
		Latitude:  10,
		Longitude: 13,
	}); err != nil {
		t.Fatal(err)
	}
	{
		got := len(ts.Requests())
		if want := 1; got != want {
			t.Errorf("got %v\nwant %v", got, want)
		}
	}
	req := ts.Requests()[0]
	{
		got := int32(req.Message["longitude"].(float64))
		if want := int32(13); got != want {
			t.Errorf("got %v\nwant %v", got, want)
		}
	}
}

Dynamic Response

grpcstub can return responses dynamically using the protocol buffer schema.

Dynamic response to all requests

ts := grpcstub.NewServer(t, "path/to/protobuf")
t.Cleanup(func() {
	ts.Close()
})
ts.ResponseDynamic()

Dynamic response to a request to a specific method (rpc)

ts := grpcstub.NewServer(t, "path/to/protobuf")
t.Cleanup(func() {
	ts.Close()
})
ts.Service("routeguide.RouteGuide").Method("GetFeature").ResponseDynamic()

Dynamic response with your own generators

ts := grpcstub.NewServer(t, "path/to/protobuf")
t.Cleanup(func() {
	ts.Close()
})
fk := faker.New()
want := time.Now()
opts := []GeneratorOption{
	Generator("*_id", func(r *grpcstub.Request) any {
		return fk.UUID().V4()
	}),
	Generator("*_time", func(r *grpcstub.Request) any {
		return want
	}),
}
ts.ResponseDynamic(opts...)

Test data

• https://github.com/grpc/grpc-go/blob/master/examples/route_guide/routeguide/route_guide.proto

References

• monlabs/grpc-mock: Run a gRPC mock server by using protobuf reflection.