Add custom instance config to tests

spanner/integration_test.go

@@ -63,6 +63,11 @@ var (
 	// by setting the environment variable GCLOUD_TESTS_GOLANG_SPANNER_HOST
 	spannerHost = getSpannerHost()
 
+	// instanceConfig specifies the instance config used to create a instance for testing.
+	// It can be changed by setting the environment variable
+	// GCLOUD_TESTS_GOLANG_SPANNER_INSTANCE_CONFIG.
+	instanceConfig = getInstanceConfig()
+
 	dbNameSpace       = uid.NewSpace("gotest", &uid.Options{Sep: '_', Short: true})
 	instanceNameSpace = uid.NewSpace("gotest", &uid.Options{Sep: '-', Short: true})
 	backupIDSpace     = uid.NewSpace("gotest", &uid.Options{Sep: '_', Short: true})
@@ -204,6 +209,10 @@ func getSpannerHost() string {
 	return os.Getenv("GCLOUD_TESTS_GOLANG_SPANNER_HOST")
 }
 
+func getInstanceConfig() string {
+	return os.Getenv("GCLOUD_TESTS_GOLANG_SPANNER_INSTANCE_CONFIG")
+}
+
 const (
 	str1 = "alice"
 	str2 = "a@example.com"
@@ -262,6 +271,10 @@ func initIntegrationTests() (cleanup func()) {
 	if err != nil {
 		log.Fatalf("Cannot get any instance configurations.\nPlease make sure the Cloud Spanner API is enabled for the test project.\nGet error: %v", err)
 	}
+	configName := config.Name
+	if instanceConfig != "" {
+		configName = fmt.Sprintf("projects/%s/instanceConfigs/%s", testProjectID, instanceConfig)
+	}
 
 	// First clean up any old test instances before we start the actual testing
 	// as these might cause this test run to fail.
@@ -272,7 +285,7 @@ func initIntegrationTests() (cleanup func()) {
 		Parent:     fmt.Sprintf("projects/%s", testProjectID),
 		InstanceId: testInstanceID,
 		Instance: &instancepb.Instance{
-			Config:      config.Name,
+			Config:      configName,
 			DisplayName: testInstanceID,
 			NodeCount:   1,
 		},