test: add a test for clientConn close with pending RPC (#5264)

test/clientconn_test.go

@@ -0,0 +1,89 @@
+/*
+ *
+ * Copyright 2022 gRPC authors.
+ *
+ * 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 test
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/internal/channelz"
+	"google.golang.org/grpc/resolver/manual"
+	"google.golang.org/grpc/status"
+	testgrpc "google.golang.org/grpc/test/grpc_testing"
+	testpb "google.golang.org/grpc/test/grpc_testing"
+)
+
+// TestClientConnClose_WithPendingRPC tests the scenario where the channel has
+// not yet received any update from the name resolver and hence RPCs are
+// blocking. The test verifies that closing the ClientConn unblocks the RPC with
+// the expected error code.
+func (s) TestClientConnClose_WithPendingRPC(t *testing.T) {
+	// Initialize channelz. Used to determine pending RPC count.
+	czCleanup := channelz.NewChannelzStorageForTesting()
+	defer czCleanupWrapper(czCleanup, t)
+
+	r := manual.NewBuilderWithScheme("whatever")
+	cc, err := grpc.Dial(r.Scheme()+":///test.server", grpc.WithTransportCredentials(insecure.NewCredentials()), grpc.WithResolvers(r))
+	if err != nil {
+		t.Fatalf("grpc.Dial() failed: %v", err)
+	}
+	client := testgrpc.NewTestServiceClient(cc)
+
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	doneErrCh := make(chan error, 1)
+	go func() {
+		// This RPC would block until the ClientConn is closed, because the
+		// resolver has not provided its first update yet.
+		_, err := client.EmptyCall(ctx, &testpb.Empty{})
+		if status.Code(err) != codes.Canceled || !strings.Contains(err.Error(), "client connection is closing") {
+			doneErrCh <- fmt.Errorf("EmptyCall() = %v, want %s", err, codes.Canceled)
+		}
+		doneErrCh <- nil
+	}()
+
+	// Make sure that there is one pending RPC on the ClientConn before attempting
+	// to close it. If we don't do this, cc.Close() can happen before the above
+	// goroutine gets to make the RPC.
+	for {
+		if err := ctx.Err(); err != nil {
+			t.Fatal(err)
+		}
+		tcs, _ := channelz.GetTopChannels(0, 0)
+		if len(tcs) != 1 {
+			t.Fatalf("there should only be one top channel, not %d", len(tcs))
+		}
+		started := tcs[0].ChannelData.CallsStarted
+		completed := tcs[0].ChannelData.CallsSucceeded + tcs[0].ChannelData.CallsFailed
+		if (started - completed) == 1 {
+			break
+		}
+		time.Sleep(defaultTestShortTimeout)
+	}
+	cc.Close()
+	if err := <-doneErrCh; err != nil {
+		t.Fatal(err)
+	}
+}