/* * * Copyright 2014 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 grpc import ( "errors" "fmt" "math" "net" "sync/atomic" "testing" "time" "golang.org/x/net/context" "golang.org/x/net/http2" "google.golang.org/grpc/connectivity" "google.golang.org/grpc/credentials" "google.golang.org/grpc/internal/backoff" "google.golang.org/grpc/internal/leakcheck" "google.golang.org/grpc/internal/transport" "google.golang.org/grpc/keepalive" "google.golang.org/grpc/naming" "google.golang.org/grpc/resolver" "google.golang.org/grpc/resolver/manual" _ "google.golang.org/grpc/resolver/passthrough" "google.golang.org/grpc/testdata" ) var ( mutableMinConnectTimeout = time.Second * 20 ) func init() { getMinConnectTimeout = func() time.Duration { return time.Duration(atomic.LoadInt64((*int64)(&mutableMinConnectTimeout))) } } func assertState(wantState connectivity.State, cc *ClientConn) (connectivity.State, bool) { ctx, cancel := context.WithTimeout(context.Background(), time.Second) defer cancel() var state connectivity.State for state = cc.GetState(); state != wantState && cc.WaitForStateChange(ctx, state); state = cc.GetState() { } return state, state == wantState } func TestDialWithMultipleBackendsNotSendingServerPreface(t *testing.T) { defer leakcheck.Check(t) numServers := 2 servers := make([]net.Listener, numServers) var err error for i := 0; i < numServers; i++ { servers[i], err = net.Listen("tcp", "localhost:0") if err != nil { t.Fatalf("Error while listening. Err: %v", err) } } dones := make([]chan struct{}, numServers) for i := 0; i < numServers; i++ { dones[i] = make(chan struct{}) } for i := 0; i < numServers; i++ { go func(i int) { defer func() { close(dones[i]) }() conn, err := servers[i].Accept() if err != nil { t.Errorf("Error while accepting. Err: %v", err) return } defer conn.Close() switch i { case 0: // 1st server accepts the connection and immediately closes it. case 1: // 2nd server accepts the connection and sends settings frames. framer := http2.NewFramer(conn, conn) if err := framer.WriteSettings(http2.Setting{}); err != nil { t.Errorf("Error while writing settings frame. %v", err) return } conn.SetDeadline(time.Now().Add(time.Second)) buf := make([]byte, 1024) for { // Make sure the connection stays healthy. _, err = conn.Read(buf) if err == nil { continue } if nerr, ok := err.(net.Error); !ok || !nerr.Timeout() { t.Errorf("Server expected the conn.Read(_) to timeout instead got error: %v", err) } return } } }(i) } r, cleanup := manual.GenerateAndRegisterManualResolver() defer cleanup() resolvedAddrs := make([]resolver.Address, numServers) for i := 0; i < numServers; i++ { resolvedAddrs[i] = resolver.Address{Addr: servers[i].Addr().String()} } r.InitialAddrs(resolvedAddrs) client, err := Dial(r.Scheme()+":///test.server", WithInsecure()) if err != nil { t.Errorf("Dial failed. Err: %v", err) } else { defer client.Close() } time.Sleep(time.Second) // Close the servers after a second for cleanup. for _, s := range servers { s.Close() } for _, done := range dones { <-done } } func TestDialWaitsForServerSettings(t *testing.T) { defer leakcheck.Check(t) lis, err := net.Listen("tcp", "localhost:0") if err != nil { t.Fatalf("Error while listening. Err: %v", err) } defer lis.Close() done := make(chan struct{}) sent := make(chan struct{}) dialDone := make(chan struct{}) go func() { // Launch the server. defer func() { close(done) }() conn, err := lis.Accept() if err != nil { t.Errorf("Error while accepting. Err: %v", err) return } defer conn.Close() // Sleep for a little bit to make sure that Dial on client // side blocks until settings are received. time.Sleep(500 * time.Millisecond) framer := http2.NewFramer(conn, conn) close(sent) if err := framer.WriteSettings(http2.Setting{}); err != nil { t.Errorf("Error while writing settings. Err: %v", err) return } <-dialDone // Close conn only after dial returns. }() ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second) defer cancel() client, err := DialContext(ctx, lis.Addr().String(), WithInsecure(), WithWaitForHandshake(), WithBlock()) close(dialDone) if err != nil { t.Fatalf("Error while dialing. Err: %v", err) } defer client.Close() select { case <-sent: default: t.Fatalf("Dial returned before server settings were sent") } <-done } func TestDialWaitsForServerSettingsAndFails(t *testing.T) { defer leakcheck.Check(t) lis, err := net.Listen("tcp", "localhost:0") if err != nil { t.Fatalf("Error while listening. Err: %v", err) } done := make(chan struct{}) numConns := 0 go func() { // Launch the server. defer func() { close(done) }() for { conn, err := lis.Accept() if err != nil { break } numConns++ defer conn.Close() } }() getMinConnectTimeout = func() time.Duration { return time.Second / 2 } ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second) defer cancel() client, err := DialContext(ctx, lis.Addr().String(), WithInsecure(), WithWaitForHandshake(), WithBlock()) lis.Close() if err == nil { client.Close() t.Fatalf("Unexpected success (err=nil) while dialing") } if err != context.DeadlineExceeded { t.Fatalf("DialContext(_) = %v; want context.DeadlineExceeded", err) } if numConns < 2 { t.Fatalf("dial attempts: %v; want > 1", numConns) } <-done } func TestCloseConnectionWhenServerPrefaceNotReceived(t *testing.T) { // 1. Client connects to a server that doesn't send preface. // 2. After minConnectTimeout(500 ms here), client disconnects and retries. // 3. The new server sends its preface. // 4. Client doesn't kill the connection this time. mctBkp := getMinConnectTimeout() defer func() { atomic.StoreInt64((*int64)(&mutableMinConnectTimeout), int64(mctBkp)) }() defer leakcheck.Check(t) atomic.StoreInt64((*int64)(&mutableMinConnectTimeout), int64(time.Millisecond)*500) lis, err := net.Listen("tcp", "localhost:0") if err != nil { t.Fatalf("Error while listening. Err: %v", err) } var ( conn2 net.Conn over uint32 ) defer func() { lis.Close() // conn2 shouldn't be closed until the client has // observed a successful test. if conn2 != nil { conn2.Close() } }() done := make(chan struct{}) accepted := make(chan struct{}) go func() { // Launch the server. defer close(done) conn1, err := lis.Accept() if err != nil { t.Errorf("Error while accepting. Err: %v", err) return } defer conn1.Close() // Don't send server settings and the client should close the connection and try again. conn2, err = lis.Accept() // Accept a reconnection request from client. if err != nil { t.Errorf("Error while accepting. Err: %v", err) return } close(accepted) framer := http2.NewFramer(conn2, conn2) if err = framer.WriteSettings(http2.Setting{}); err != nil { t.Errorf("Error while writing settings. Err: %v", err) return } b := make([]byte, 8) for { _, err = conn2.Read(b) if err == nil { continue } if atomic.LoadUint32(&over) == 1 { // The connection stayed alive for the timer. // Success. return } t.Errorf("Unexpected error while reading. Err: %v, want timeout error", err) break } }() client, err := Dial(lis.Addr().String(), WithInsecure()) if err != nil { t.Fatalf("Error while dialing. Err: %v", err) } // wait for connection to be accepted on the server. timer := time.NewTimer(time.Second * 10) select { case <-accepted: case <-timer.C: t.Fatalf("Client didn't make another connection request in time.") } // Make sure the connection stays alive for sometime. time.Sleep(time.Second * 2) atomic.StoreUint32(&over, 1) client.Close() <-done } func TestBackoffWhenNoServerPrefaceReceived(t *testing.T) { defer leakcheck.Check(t) lis, err := net.Listen("tcp", "localhost:0") if err != nil { t.Fatalf("Error while listening. Err: %v", err) } defer lis.Close() done := make(chan struct{}) go func() { // Launch the server. defer func() { close(done) }() conn, err := lis.Accept() // Accept the connection only to close it immediately. if err != nil { t.Errorf("Error while accepting. Err: %v", err) return } prevAt := time.Now() conn.Close() var prevDuration time.Duration // Make sure the retry attempts are backed off properly. for i := 0; i < 3; i++ { conn, err := lis.Accept() if err != nil { t.Errorf("Error while accepting. Err: %v", err) return } meow := time.Now() conn.Close() dr := meow.Sub(prevAt) if dr <= prevDuration { t.Errorf("Client backoff did not increase with retries. Previous duration: %v, current duration: %v", prevDuration, dr) return } prevDuration = dr prevAt = meow } }() client, err := Dial(lis.Addr().String(), WithInsecure()) if err != nil { t.Fatalf("Error while dialing. Err: %v", err) } defer client.Close() <-done } func TestConnectivityStates(t *testing.T) { defer leakcheck.Check(t) servers, resolver, cleanup := startServers(t, 2, math.MaxUint32) defer cleanup() cc, err := Dial("passthrough:///foo.bar.com", WithBalancer(RoundRobin(resolver)), WithInsecure()) if err != nil { t.Fatalf("Dial(\"foo.bar.com\", WithBalancer(_)) = _, %v, want _ ", err) } defer cc.Close() wantState := connectivity.Ready if state, ok := assertState(wantState, cc); !ok { t.Fatalf("asserState(%s) = %s, false, want %s, true", wantState, state, wantState) } // Send an update to delete the server connection (tearDown addrConn). update := []*naming.Update{ { Op: naming.Delete, Addr: "localhost:" + servers[0].port, }, } resolver.w.inject(update) wantState = connectivity.TransientFailure if state, ok := assertState(wantState, cc); !ok { t.Fatalf("asserState(%s) = %s, false, want %s, true", wantState, state, wantState) } update[0] = &naming.Update{ Op: naming.Add, Addr: "localhost:" + servers[1].port, } resolver.w.inject(update) wantState = connectivity.Ready if state, ok := assertState(wantState, cc); !ok { t.Fatalf("asserState(%s) = %s, false, want %s, true", wantState, state, wantState) } } func TestWithTimeout(t *testing.T) { defer leakcheck.Check(t) conn, err := Dial("passthrough:///Non-Existent.Server:80", WithTimeout(time.Millisecond), WithBlock(), WithInsecure()) if err == nil { conn.Close() } if err != context.DeadlineExceeded { t.Fatalf("Dial(_, _) = %v, %v, want %v", conn, err, context.DeadlineExceeded) } } func TestWithTransportCredentialsTLS(t *testing.T) { ctx, cancel := context.WithTimeout(context.Background(), time.Millisecond) defer cancel() defer leakcheck.Check(t) creds, err := credentials.NewClientTLSFromFile(testdata.Path("ca.pem"), "x.test.youtube.com") if err != nil { t.Fatalf("Failed to create credentials %v", err) } conn, err := DialContext(ctx, "passthrough:///Non-Existent.Server:80", WithTransportCredentials(creds), WithBlock()) if err == nil { conn.Close() } if err != context.DeadlineExceeded { t.Fatalf("Dial(_, _) = %v, %v, want %v", conn, err, context.DeadlineExceeded) } } func TestDefaultAuthority(t *testing.T) { defer leakcheck.Check(t) target := "Non-Existent.Server:8080" conn, err := Dial(target, WithInsecure()) if err != nil { t.Fatalf("Dial(_, _) = _, %v, want _, ", err) } defer conn.Close() if conn.authority != target { t.Fatalf("%v.authority = %v, want %v", conn, conn.authority, target) } } func TestTLSServerNameOverwrite(t *testing.T) { defer leakcheck.Check(t) overwriteServerName := "over.write.server.name" creds, err := credentials.NewClientTLSFromFile(testdata.Path("ca.pem"), overwriteServerName) if err != nil { t.Fatalf("Failed to create credentials %v", err) } conn, err := Dial("passthrough:///Non-Existent.Server:80", WithTransportCredentials(creds)) if err != nil { t.Fatalf("Dial(_, _) = _, %v, want _, ", err) } defer conn.Close() if conn.authority != overwriteServerName { t.Fatalf("%v.authority = %v, want %v", conn, conn.authority, overwriteServerName) } } func TestWithAuthority(t *testing.T) { defer leakcheck.Check(t) overwriteServerName := "over.write.server.name" conn, err := Dial("passthrough:///Non-Existent.Server:80", WithInsecure(), WithAuthority(overwriteServerName)) if err != nil { t.Fatalf("Dial(_, _) = _, %v, want _, ", err) } defer conn.Close() if conn.authority != overwriteServerName { t.Fatalf("%v.authority = %v, want %v", conn, conn.authority, overwriteServerName) } } func TestWithAuthorityAndTLS(t *testing.T) { defer leakcheck.Check(t) overwriteServerName := "over.write.server.name" creds, err := credentials.NewClientTLSFromFile(testdata.Path("ca.pem"), overwriteServerName) if err != nil { t.Fatalf("Failed to create credentials %v", err) } conn, err := Dial("passthrough:///Non-Existent.Server:80", WithTransportCredentials(creds), WithAuthority("no.effect.authority")) if err != nil { t.Fatalf("Dial(_, _) = _, %v, want _, ", err) } defer conn.Close() if conn.authority != overwriteServerName { t.Fatalf("%v.authority = %v, want %v", conn, conn.authority, overwriteServerName) } } func TestDialContextCancel(t *testing.T) { defer leakcheck.Check(t) ctx, cancel := context.WithCancel(context.Background()) cancel() if _, err := DialContext(ctx, "Non-Existent.Server:80", WithBlock(), WithInsecure()); err != context.Canceled { t.Fatalf("DialContext(%v, _) = _, %v, want _, %v", ctx, err, context.Canceled) } } type failFastError struct{} func (failFastError) Error() string { return "failfast" } func (failFastError) Temporary() bool { return false } func TestDialContextFailFast(t *testing.T) { defer leakcheck.Check(t) ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second) defer cancel() failErr := failFastError{} dialer := func(string, time.Duration) (net.Conn, error) { return nil, failErr } _, err := DialContext(ctx, "Non-Existent.Server:80", WithBlock(), WithInsecure(), WithDialer(dialer), FailOnNonTempDialError(true)) if terr, ok := err.(transport.ConnectionError); !ok || terr.Origin() != failErr { t.Fatalf("DialContext() = _, %v, want _, %v", err, failErr) } } // blockingBalancer mimics the behavior of balancers whose initialization takes a long time. // In this test, reading from blockingBalancer.Notify() blocks forever. type blockingBalancer struct { ch chan []Address } func newBlockingBalancer() Balancer { return &blockingBalancer{ch: make(chan []Address)} } func (b *blockingBalancer) Start(target string, config BalancerConfig) error { return nil } func (b *blockingBalancer) Up(addr Address) func(error) { return nil } func (b *blockingBalancer) Get(ctx context.Context, opts BalancerGetOptions) (addr Address, put func(), err error) { return Address{}, nil, nil } func (b *blockingBalancer) Notify() <-chan []Address { return b.ch } func (b *blockingBalancer) Close() error { close(b.ch) return nil } func TestDialWithBlockingBalancer(t *testing.T) { defer leakcheck.Check(t) ctx, cancel := context.WithCancel(context.Background()) dialDone := make(chan struct{}) go func() { DialContext(ctx, "Non-Existent.Server:80", WithBlock(), WithInsecure(), WithBalancer(newBlockingBalancer())) close(dialDone) }() cancel() <-dialDone } // securePerRPCCredentials always requires transport security. type securePerRPCCredentials struct{} func (c securePerRPCCredentials) GetRequestMetadata(ctx context.Context, uri ...string) (map[string]string, error) { return nil, nil } func (c securePerRPCCredentials) RequireTransportSecurity() bool { return true } func TestCredentialsMisuse(t *testing.T) { defer leakcheck.Check(t) tlsCreds, err := credentials.NewClientTLSFromFile(testdata.Path("ca.pem"), "x.test.youtube.com") if err != nil { t.Fatalf("Failed to create authenticator %v", err) } // Two conflicting credential configurations if _, err := Dial("passthrough:///Non-Existent.Server:80", WithTransportCredentials(tlsCreds), WithBlock(), WithInsecure()); err != errCredentialsConflict { t.Fatalf("Dial(_, _) = _, %v, want _, %v", err, errCredentialsConflict) } // security info on insecure connection if _, err := Dial("passthrough:///Non-Existent.Server:80", WithPerRPCCredentials(securePerRPCCredentials{}), WithBlock(), WithInsecure()); err != errTransportCredentialsMissing { t.Fatalf("Dial(_, _) = _, %v, want _, %v", err, errTransportCredentialsMissing) } } func TestWithBackoffConfigDefault(t *testing.T) { defer leakcheck.Check(t) testBackoffConfigSet(t, &DefaultBackoffConfig) } func TestWithBackoffConfig(t *testing.T) { defer leakcheck.Check(t) b := BackoffConfig{MaxDelay: DefaultBackoffConfig.MaxDelay / 2} expected := b testBackoffConfigSet(t, &expected, WithBackoffConfig(b)) } func TestWithBackoffMaxDelay(t *testing.T) { defer leakcheck.Check(t) md := DefaultBackoffConfig.MaxDelay / 2 expected := BackoffConfig{MaxDelay: md} testBackoffConfigSet(t, &expected, WithBackoffMaxDelay(md)) } func testBackoffConfigSet(t *testing.T, expected *BackoffConfig, opts ...DialOption) { opts = append(opts, WithInsecure()) conn, err := Dial("passthrough:///foo:80", opts...) if err != nil { t.Fatalf("unexpected error dialing connection: %v", err) } defer conn.Close() if conn.dopts.bs == nil { t.Fatalf("backoff config not set") } actual, ok := conn.dopts.bs.(backoff.Exponential) if !ok { t.Fatalf("unexpected type of backoff config: %#v", conn.dopts.bs) } expectedValue := backoff.Exponential{ MaxDelay: expected.MaxDelay, } if actual != expectedValue { t.Fatalf("unexpected backoff config on connection: %v, want %v", actual, expected) } } // emptyBalancer returns an empty set of servers. type emptyBalancer struct { ch chan []Address } func newEmptyBalancer() Balancer { return &emptyBalancer{ch: make(chan []Address, 1)} } func (b *emptyBalancer) Start(_ string, _ BalancerConfig) error { b.ch <- nil return nil } func (b *emptyBalancer) Up(_ Address) func(error) { return nil } func (b *emptyBalancer) Get(_ context.Context, _ BalancerGetOptions) (Address, func(), error) { return Address{}, nil, nil } func (b *emptyBalancer) Notify() <-chan []Address { return b.ch } func (b *emptyBalancer) Close() error { close(b.ch) return nil } func TestNonblockingDialWithEmptyBalancer(t *testing.T) { defer leakcheck.Check(t) ctx, cancel := context.WithCancel(context.Background()) defer cancel() dialDone := make(chan error) go func() { dialDone <- func() error { conn, err := DialContext(ctx, "Non-Existent.Server:80", WithInsecure(), WithBalancer(newEmptyBalancer())) if err != nil { return err } return conn.Close() }() }() if err := <-dialDone; err != nil { t.Fatalf("unexpected error dialing connection: %s", err) } } func TestResolverServiceConfigBeforeAddressNotPanic(t *testing.T) { defer leakcheck.Check(t) r, rcleanup := manual.GenerateAndRegisterManualResolver() defer rcleanup() cc, err := Dial(r.Scheme()+":///test.server", WithInsecure()) if err != nil { t.Fatalf("failed to dial: %v", err) } defer cc.Close() // SwitchBalancer before NewAddress. There was no balancer created, this // makes sure we don't call close on nil balancerWrapper. r.NewServiceConfig(`{"loadBalancingPolicy": "round_robin"}`) // This should not panic. time.Sleep(time.Second) // Sleep to make sure the service config is handled by ClientConn. } func TestResolverServiceConfigWhileClosingNotPanic(t *testing.T) { defer leakcheck.Check(t) for i := 0; i < 10; i++ { // Run this multiple times to make sure it doesn't panic. r, rcleanup := manual.GenerateAndRegisterManualResolver() defer rcleanup() cc, err := Dial(r.Scheme()+":///test.server", WithInsecure()) if err != nil { t.Fatalf("failed to dial: %v", err) } // Send a new service config while closing the ClientConn. go cc.Close() go r.NewServiceConfig(`{"loadBalancingPolicy": "round_robin"}`) // This should not panic. } } func TestResolverEmptyUpdateNotPanic(t *testing.T) { defer leakcheck.Check(t) r, rcleanup := manual.GenerateAndRegisterManualResolver() defer rcleanup() cc, err := Dial(r.Scheme()+":///test.server", WithInsecure()) if err != nil { t.Fatalf("failed to dial: %v", err) } defer cc.Close() // This make sure we don't create addrConn with empty address list. r.NewAddress([]resolver.Address{}) // This should not panic. time.Sleep(time.Second) // Sleep to make sure the service config is handled by ClientConn. } func TestClientUpdatesParamsAfterGoAway(t *testing.T) { defer leakcheck.Check(t) lis, err := net.Listen("tcp", "localhost:0") if err != nil { t.Fatalf("Failed to listen. Err: %v", err) } defer lis.Close() addr := lis.Addr().String() s := NewServer() go s.Serve(lis) defer s.Stop() cc, err := Dial(addr, WithBlock(), WithInsecure(), WithKeepaliveParams(keepalive.ClientParameters{ Time: 50 * time.Millisecond, Timeout: 100 * time.Millisecond, PermitWithoutStream: true, })) if err != nil { t.Fatalf("Dial(%s, _) = _, %v, want _, ", addr, err) } defer cc.Close() time.Sleep(1 * time.Second) cc.mu.RLock() defer cc.mu.RUnlock() v := cc.mkp.Time if v < 100*time.Millisecond { t.Fatalf("cc.dopts.copts.Keepalive.Time = %v , want 100ms", v) } } func TestDisableServiceConfigOption(t *testing.T) { r, cleanup := manual.GenerateAndRegisterManualResolver() defer cleanup() addr := r.Scheme() + ":///non.existent" cc, err := Dial(addr, WithInsecure(), WithDisableServiceConfig()) if err != nil { t.Fatalf("Dial(%s, _) = _, %v, want _, ", addr, err) } defer cc.Close() r.NewServiceConfig(`{ "methodConfig": [ { "name": [ { "service": "foo", "method": "Bar" } ], "waitForReady": true } ] }`) time.Sleep(1 * time.Second) m := cc.GetMethodConfig("/foo/Bar") if m.WaitForReady != nil { t.Fatalf("want: method (\"/foo/bar/\") config to be empty, got: %v", m) } } func TestGetClientConnTarget(t *testing.T) { addr := "nonexist:///non.existent" cc, err := Dial(addr, WithInsecure()) if err != nil { t.Fatalf("Dial(%s, _) = _, %v, want _, ", addr, err) } defer cc.Close() if cc.Target() != addr { t.Fatalf("Target() = %s, want %s", cc.Target(), addr) } } type backoffForever struct{} func (b backoffForever) Backoff(int) time.Duration { return time.Duration(math.MaxInt64) } func TestResetConnectBackoff(t *testing.T) { defer leakcheck.Check(t) dials := make(chan struct{}) defer func() { // If we fail, let the http2client break out of dialing. select { case <-dials: default: } }() dialer := func(string, time.Duration) (net.Conn, error) { dials <- struct{}{} return nil, errors.New("failed to fake dial") } cc, err := Dial("any", WithInsecure(), WithDialer(dialer), withBackoff(backoffForever{})) if err != nil { t.Fatalf("Dial() = _, %v; want _, nil", err) } defer cc.Close() select { case <-dials: case <-time.NewTimer(10 * time.Second).C: t.Fatal("Failed to call dial within 10s") } select { case <-dials: t.Fatal("Dial called unexpectedly before resetting backoff") case <-time.NewTimer(100 * time.Millisecond).C: } cc.ResetConnectBackoff() select { case <-dials: case <-time.NewTimer(10 * time.Second).C: t.Fatal("Failed to call dial within 10s after resetting backoff") } } func TestBackoffCancel(t *testing.T) { defer leakcheck.Check(t) dialStrCh := make(chan string) cc, err := Dial("any", WithInsecure(), WithDialer(func(t string, _ time.Duration) (net.Conn, error) { dialStrCh <- t return nil, fmt.Errorf("test dialer, always error") })) if err != nil { t.Fatalf("Failed to create ClientConn: %v", err) } <-dialStrCh cc.Close() // Should not leak. May need -count 5000 to exercise. }