feat(pubsub/pstest): add ability to create a pstest server listening …

…on (#4459)

a specified port

Signed-off-by: Danny Cao <caoxiaohua@gmail.com>

pubsub/pstest/examples_test.go

@@ -42,3 +42,23 @@ func ExampleNewServer() {
 	defer client.Close()
 	_ = client // TODO: Use the client.
 }
+
+func ExampleNewServerWithPort() {
+	ctx := context.Background()
+	// Start a fake server running locally at 9001.
+	srv := pstest.NewServerWithPort(9001)
+	defer srv.Close()
+	// Connect to the server without using TLS.
+	conn, err := grpc.Dial(srv.Addr, grpc.WithInsecure())
+	if err != nil {
+		// TODO: Handle error.
+	}
+	defer conn.Close()
+	// Use the connection when creating a pubsub client.
+	client, err := pubsub.NewClient(ctx, "project", option.WithGRPCConn(conn))
+	if err != nil {
+		// TODO: Handle error.
+	}
+	defer client.Close()
+	_ = client // TODO: Use the client.
+}

pubsub/pstest/fake.go

@@ -114,9 +114,14 @@ type GServer struct {
 
 // NewServer creates a new fake server running in the current process.
 func NewServer(opts ...ServerReactorOption) *Server {
-	srv, err := testutil.NewServer()
+	return NewServerWithPort(0, opts...)
+}
+
+// NewServerWithPort creates a new fake server running in the current process at the specified port.
+func NewServerWithPort(port int, opts ...ServerReactorOption) *Server {
+	srv, err := testutil.NewServerWithPort(port)
 	if err != nil {
-		panic(fmt.Sprintf("pstest.NewServer: %v", err))
+		panic(fmt.Sprintf("pstest.NewServerWithPort: %v", err))
 	}
 	reactorOptions := ReactorOptions{}
 	for _, opt := range opts {

pubsub/pstest/fake_test.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"net"
 	"reflect"
 	"strings"
 	"sync"
@@ -34,6 +35,31 @@ import (
 	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
+func TestNewServerWithPort(t *testing.T) {
+	// Allocate an available port to use with NewServerWithPort and then close it so it's available.
+	// Note: There is no guarantee that the port does not become used between closing
+	// the listener and creating the new server with NewServerWithPort, but the chances are
+	// very small.
+	l, err := net.Listen("tcp", ":0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	port := l.Addr().(*net.TCPAddr).Port
+	l.Close()
+
+	// Pass a non 0 port to demonstrate we can pass a hardcoded port for the server to listen on
+	srv := NewServerWithPort(port)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer srv.Close()
+	conn, err := grpc.Dial(srv.Addr, grpc.WithInsecure())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close()
+}
+
 func TestTopics(t *testing.T) {
 	pclient, _, server, cleanup := newFake(context.TODO(), t)
 	defer cleanup()