race fix

Signed-off-by: Angelo De Caro <adc@zurich.ibm.com>

Author: adecaro

token/services/identity/membership/lm_discovery_test.go

@@ -240,8 +240,11 @@ func TestLocalMembership_Notifier(t *testing.T) {
 
 	iss.IteratorConfigurationsReturns(&mock.IdentityConfigurationIterator{}, nil)
 
+	var mu sync.Mutex
 	var subCallback fscdriver.TriggerCallback
 	notifier.SubscribeStub = func(callback fscdriver.TriggerCallback) error {
+		mu.Lock()
+		defer mu.Unlock()
 		subCallback = callback
 
 		return nil
@@ -251,14 +254,20 @@ func TestLocalMembership_Notifier(t *testing.T) {
 	require.NoError(t, err)
 
 	assert.Eventually(t, func() bool {
+		mu.Lock()
+		defer mu.Unlock()
+
 		return subCallback != nil
 	}, 2*time.Second, 100*time.Millisecond)
 
 	newConfig := idriver.IdentityConfiguration{ID: "new", URL: "/tmp/new", Type: "testType"}
 	iss.GetConfigurationReturns(&newConfig, nil)
 
 	// Simulate notification
-	subCallback(idriver.Insert, map[idriver.ColumnKey]string{
+	mu.Lock()
+	callback := subCallback
+	mu.Unlock()
+	callback(idriver.Insert, map[idriver.ColumnKey]string{
 		"id":   "new",
 		"type": "testType",
 		"url":  "/tmp/new",