Add integration tests for protoc-gen-go-grpc (#3787)

* Add integration tests for protoc-gen-go-grpc

* Update tests/integration/grpc_plugin/BUILD.bazel

Co-authored-by: Marcel <[email protected]>

* fix build

---------

Co-authored-by: Marcel <[email protected]>

tests/integration/grpc_plugin/BUILD.bazel

@@ -0,0 +1,35 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@io_bazel_rules_go//proto:def.bzl", "go_grpc_library")
+load("@rules_proto//proto:defs.bzl", "proto_library")
+
+proto_library(
+    name = "hello_proto",
+    srcs = ["hello.proto"],
+    deps = [],
+)
+
+go_grpc_library(
+    name = "hello_go_proto",
+    importpath = "github.com/bazelbuild/rules_go/tests/integration/grpc_plugin/hello_proto",
+    proto = ":hello_proto",
+    deps = [],
+)
+
+go_library(
+    name = "hello",
+    srcs = ["hello.go"],
+    importpath = "github.com/bazelbuild/rules_go/tests/integration/grpc_plugin/hello",
+    deps = [
+        ":hello_go_proto",
+    ],
+)
+
+go_test(
+    name = "hello_test",
+    srcs = ["hello_test.go"],
+    deps = [
+        ":hello",
+        ":hello_go_proto",
+        "@org_golang_google_grpc//:go_default_library",
+    ],
+)

tests/integration/grpc_plugin/README.rst

@@ -0,0 +1,9 @@
+Testing that the protoc-gen-go-grpc plugin works
+=======================================
+
+hello_test
+------------------
+
+Verifies that the generated code for a simple gRPC service:
+- exposes a `pb.UnimplementedGreetServer` style struct
+- exposes a `pb.RegisterGreetServer` method that accepts a `grpc.ServiceRegistrar` instead of a raw `*grpc.Server`

tests/integration/grpc_plugin/hello.go

@@ -0,0 +1,33 @@
+// Copyright 2023 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package hello
+
+import (
+	"context"
+
+	pb "github.com/bazelbuild/rules_go/tests/integration/grpc_plugin/hello_proto"
+)
+
+type greeter struct {
+	pb.UnimplementedGreetServer
+}
+
+func GreetServer() pb.GreetServer {
+	return &greeter{}
+}
+
+func (g *greeter) Hello(ctx context.Context, r *pb.HelloRequest) (*pb.HelloResponse, error) {
+	return &pb.HelloResponse{}, nil
+}

tests/integration/grpc_plugin/hello.proto

@@ -0,0 +1,26 @@
+// Copyright 2023 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package rules_go.tests.integration.grpc_plugin;
+
+option go_package = "github.com/bazelbuild/rules_go/tests/integration/grpc_plugin/hello_proto";
+
+service Greet {
+  rpc Hello(HelloRequest) returns (HelloResponse);
+}
+
+message HelloRequest {}
+message HelloResponse {}

tests/integration/grpc_plugin/hello_test.go

@@ -0,0 +1,40 @@
+// Copyright 2023 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package hello_test
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/bazelbuild/rules_go/tests/integration/grpc_plugin/hello"
+	pb "github.com/bazelbuild/rules_go/tests/integration/grpc_plugin/hello_proto"
+	"google.golang.org/grpc"
+)
+
+func Test_ServiceRegistrar(t *testing.T) {
+	fr := &fakeRegistrar{}
+	pb.RegisterGreetServer(fr, hello.GreetServer())
+	if got, want := fr.services, []string{"rules_go.tests.integration.grpc_plugin.Greet"}; !reflect.DeepEqual(got, want) {
+		t.Fatalf("got %v, want %v", got, want)
+	}
+}
+
+type fakeRegistrar struct {
+	services []string
+}
+
+func (fr *fakeRegistrar) RegisterService(desc *grpc.ServiceDesc, impl any) {
+	fr.services = append(fr.services, desc.ServiceName)
+}