test/channelz: Don't try to dial non-dialable addresses

On some platforms, dialing 127.0.0.1:0 doesn't fail immediately but
rather blocks until it times out. This leads to test failures because
the leak detector identifies stray goroutines.

Even if the tests don't need the dial to succeed, create a random
listener and use that as resolved address.

Signed-off-by: Tom Wieczorek <[email protected]>

Author: twz123

test/channelz_test.go

@@ -323,7 +323,8 @@ func (s) TestCZNestedChannelRegistrationAndDeletion(t *testing.T) {
 	r := manual.NewBuilderWithScheme("whatever")
 	te.resolverScheme = r.Scheme()
 	te.clientConn(grpc.WithResolvers(r))
-	resolvedAddrs := []resolver.Address{{Addr: "127.0.0.1:0", ServerName: "grpclb.server"}}
+	localListenAddress := randomLocalListenAddress(t)
+	resolvedAddrs := []resolver.Address{{Addr: localListenAddress, ServerName: "grpclb.server"}}
 	grpclbConfig := parseServiceConfig(t, r, `{"loadBalancingPolicy": "grpclb"}`)
 	r.UpdateState(grpclbstate.Set(resolver.State{ServiceConfig: grpclbConfig}, &grpclbstate.State{BalancerAddresses: resolvedAddrs}))
 	defer te.tearDown()
@@ -342,7 +343,7 @@ func (s) TestCZNestedChannelRegistrationAndDeletion(t *testing.T) {
 	}
 
 	r.UpdateState(resolver.State{
-		Addresses:     []resolver.Address{{Addr: "127.0.0.1:0"}},
+		Addresses:     []resolver.Address{{Addr: localListenAddress}},
 		ServiceConfig: parseServiceConfig(t, r, `{"loadBalancingPolicy": "round_robin"}`),
 	})
 
@@ -1504,7 +1505,8 @@ func (s) TestCZChannelTraceCreationDeletion(t *testing.T) {
 	r := manual.NewBuilderWithScheme("whatever")
 	te.resolverScheme = r.Scheme()
 	te.clientConn(grpc.WithResolvers(r))
-	resolvedAddrs := []resolver.Address{{Addr: "127.0.0.1:0", ServerName: "grpclb.server"}}
+	localListenAddress := randomLocalListenAddress(t)
+	resolvedAddrs := []resolver.Address{{Addr: localListenAddress, ServerName: "grpclb.server"}}
 	grpclbConfig := parseServiceConfig(t, r, `{"loadBalancingPolicy": "grpclb"}`)
 	r.UpdateState(grpclbstate.Set(resolver.State{ServiceConfig: grpclbConfig}, &grpclbstate.State{BalancerAddresses: resolvedAddrs}))
 	defer te.tearDown()
@@ -1546,7 +1548,7 @@ func (s) TestCZChannelTraceCreationDeletion(t *testing.T) {
 	}
 
 	r.UpdateState(resolver.State{
-		Addresses:     []resolver.Address{{Addr: "127.0.0.1:0"}},
+		Addresses:     []resolver.Address{{Addr: localListenAddress}},
 		ServiceConfig: parseServiceConfig(t, r, `{"loadBalancingPolicy": "round_robin"}`),
 	})
 
@@ -2014,7 +2016,8 @@ func (s) TestCZTraceOverwriteChannelDeletion(t *testing.T) {
 	r := manual.NewBuilderWithScheme("whatever")
 	te.resolverScheme = r.Scheme()
 	te.clientConn(grpc.WithResolvers(r))
-	resolvedAddrs := []resolver.Address{{Addr: "127.0.0.1:0", ServerName: "grpclb.server"}}
+	localListenAddress := randomLocalListenAddress(t)
+	resolvedAddrs := []resolver.Address{{Addr: localListenAddress, ServerName: "grpclb.server"}}
 	grpclbConfig := parseServiceConfig(t, r, `{"loadBalancingPolicy": "grpclb"}`)
 	r.UpdateState(grpclbstate.Set(resolver.State{ServiceConfig: grpclbConfig}, &grpclbstate.State{BalancerAddresses: resolvedAddrs}))
 	defer te.tearDown()
@@ -2037,7 +2040,7 @@ func (s) TestCZTraceOverwriteChannelDeletion(t *testing.T) {
 	}
 
 	r.UpdateState(resolver.State{
-		Addresses:     []resolver.Address{{Addr: "127.0.0.1:0"}},
+		Addresses:     []resolver.Address{{Addr: localListenAddress}},
 		ServiceConfig: parseServiceConfig(t, r, `{"loadBalancingPolicy": "round_robin"}`),
 	})
 
@@ -2163,3 +2166,12 @@ func (s) TestCZTraceTopChannelDeletionTraceClear(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func randomLocalListenAddress(t *testing.T) string {
+	lis, err := net.Listen("tcp", "localhost:0")
+	if err != nil {
+		t.Fatalf("Failed to listen: %v", err)
+	}
+	t.Cleanup(func() { lis.Close() })
+	return lis.Addr().String()
+}