Add go_grpc_library test to BCR test module

tests/bcr/MODULE.bazel

@@ -8,9 +8,18 @@ local_path_override(
     module_name = "rules_go",
     path = "../..",
 )
-bazel_dep(name = "protobuf", version = "3.19.2")
+bazel_dep(name = "gazelle", version = "0.26.0")
+bazel_dep(name = "protobuf", version = "3.19.6")
 
 # Test that this correctly downloads the SDK by requesting it from the commandline (see presubmit.yml).
 go_sdk = use_extension("@my_rules_go//go:extensions.bzl", "go_sdk")
 go_sdk.download(name = "go_sdk", version = "1.17.5")
 use_repo(go_sdk, "go_sdk")
+
+go_deps = use_extension("@gazelle//:extensions.bzl", "go_deps")
+go_deps.module(
+    path = "google.golang.org/grpc",
+    version = "v1.50.0",
+    sum = "h1:fPVVDxY9w++VjTZsYvXWqEf9Rqar/e+9zYfxKK+W+YU=",
+)
+use_repo(go_deps, "org_golang_google_grpc")

tests/bcr/proto/BUILD.bazel

@@ -16,9 +16,23 @@ go_proto_library(
 )
 
 go_test(
-    name = "foo_test",
-    srcs = ["foo_test.go"],
+    name = "foo_proto_test",
+    srcs = ["foo_proto_test.go"],
+    deps = [":foo_go_proto"],
+)
+
+go_grpc_library(
+    name = "foo_go_grpc",
+    importpath = "example.com/foo_proto",
+    protos = [":foo_proto"],
+)
+
+go_test(
+    name = "foo_grpc_test",
+    srcs = ["foo_grpc_test.go"],
     deps = [
-        ":foo_go_proto",
+        ":foo_go_grpc",
+        "@org_golang_google_grpc//:grpc",
+        "@org_golang_google_grpc//credentials/insecure",
     ],
 )

tests/bcr/proto/foo.proto

@@ -9,3 +9,7 @@ message Foo {
   int64 value = 1;
   google.protobuf.Empty empty = 2;
 }
+
+service Fooer {
+  rpc RoundTripFoo (Foo) returns (Foo) {}
+}

tests/bcr/proto/foo_grpc_test.go

@@ -0,0 +1,62 @@
+package grpc_test
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net"
+	"testing"
+
+	"example.com/foo_proto"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+type fooerServer struct {
+}
+
+func newServer() *fooerServer {
+	return &fooerServer{}
+}
+
+func (*fooerServer) RoundTripFoo(ctx context.Context, foo *foo_proto.Foo) (*foo_proto.Foo, error) {
+	foo.Value += 1
+	return foo, nil
+}
+
+func TestRoundTripFoo(t *testing.T) {
+	// Start the server.
+	address := fmt.Sprintf("localhost:%d", 12345)
+	lis, err := net.Listen("tcp", address)
+	if err != nil {
+		log.Fatalf("failed to listen on %s: %v", address, err)
+	}
+	grpcServer := grpc.NewServer()
+	foo_proto.RegisterFooerServer(grpcServer, newServer())
+	go func() {
+		grpcServer.Serve(lis)
+	}()
+
+	// Start the client.
+	conn, err := grpc.Dial(address, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	if err != nil {
+		log.Fatalf("fail to dial %s: %v", address, err)
+	}
+	defer conn.Close()
+	client := foo_proto.NewFooerClient(conn)
+
+	// Send a message and verify that it is returned correctly.
+	msgIn := &foo_proto.Foo{
+		Value: 42,
+	}
+	msgOut, err := client.RoundTripFoo(context.TODO(), msgIn)
+	if err != nil {
+		log.Fatalf("failed to round-trip message: %v", err)
+	}
+	if msgOut.Value != 43 {
+		log.Fatalf("message did not round-trip correctly: sent %v, got %v", msgIn, msgOut)
+	}
+
+	grpcServer.GracefulStop()
+}