feat: send empty array if no resources in subscription (#239)

* feat: send empty array if no resources in subscription
* fix: simple solution for empty array
* fix: fixed subscription_test

Author: kekcleader

gateway/resolver/subscription.go

@@ -2,11 +2,12 @@ package resolver
 
 import (
 	"fmt"
-	"github.com/openmfp/golang-commons/sentry"
 	"reflect"
 	"sort"
 	"strings"
 
+	"github.com/openmfp/golang-commons/sentry"
+
 	v1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 
 	"github.com/graphql-go/graphql/language/ast"
@@ -119,6 +120,14 @@ func (r *Service) runWatch(
 		return
 	}
 
+	if !singleItem {
+		select {
+		case <-ctx.Done():
+			return
+		case resultChannel <- []map[string]interface{}{}:
+		}
+	}
+
 	watcher, err := r.runtimeClient.Watch(ctx, list, opts...)
 	if err != nil {
 		r.log.Error().Err(err).Str("gvk", gvk.String()).Msg("Failed to start watch")

tests/gateway_test/subscription_test.go

@@ -2,6 +2,11 @@ package gateway_test
 
 import (
 	"context"
+	"strconv"
+	"sync"
+	"testing"
+	"time"
+
 	"github.com/graphql-go/graphql"
 	"github.com/stretchr/testify/require"
 	appsv1 "k8s.io/api/apps/v1"
@@ -10,10 +15,6 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/labels"
 	"sigs.k8s.io/controller-runtime/pkg/client"
-	"strconv"
-	"sync"
-	"testing"
-	"time"
 )
 
 func (suite *CommonTestSuite) TestSchemaSubscribe() {
@@ -44,7 +45,7 @@ func (suite *CommonTestSuite) TestSchemaSubscribe() {
 				// this event will be received because we subscribed to replicas change.
 				suite.updateDeployment(ctx, "my-new-deployment", map[string]string{"app": "my-app", "newLabel": "changed"}, 2)
 			},
-			expectedEvents: 2,
+			expectedEvents: 3,
 		},
 		{
 			testName:       "subscribe_to_deployments_by_labels_OK",
@@ -54,7 +55,7 @@ func (suite *CommonTestSuite) TestSchemaSubscribe() {
 				// this event will be ignored because we subscribe to deployment=first labels only
 				suite.createDeployment(ctx, "my-second-deployment", map[string]string{"deployment": "second"})
 			},
-			expectedEvents: 1,
+			expectedEvents: 2,
 		},
 		{
 			testName:       "subscribe_deployments_and_delete_deployment_OK",
@@ -63,7 +64,7 @@ func (suite *CommonTestSuite) TestSchemaSubscribe() {
 				suite.createDeployment(ctx, "my-new-deployment", map[string]string{"app": "my-app"})
 				suite.deleteDeployment(ctx, "my-new-deployment")
 			},
-			expectedEvents: 2,
+			expectedEvents: 3,
 		},
 		{
 			testName:       "subscribeToClusterRole_OK",
@@ -79,7 +80,7 @@ func (suite *CommonTestSuite) TestSchemaSubscribe() {
 			setupFunc: func(ctx context.Context) {
 				suite.createClusterRole(ctx)
 			},
-			expectedEvents: 65,
+			expectedEvents: 66,
 		},
 		{
 			testName:       "incorrect_subscription_query",
@@ -107,6 +108,7 @@ func (suite *CommonTestSuite) TestSchemaSubscribe() {
 			wg := sync.WaitGroup{}
 			wg.Add(tt.expectedEvents)
 
+			eventsReceived := 0
 			go func() {
 				for {
 					select {
@@ -118,13 +120,19 @@ func (suite *CommonTestSuite) TestSchemaSubscribe() {
 						if tt.expectError && res.Errors == nil {
 							t.Errorf("Expected error but got nil")
 							cancel()
+							return
 						}
 
 						if !tt.expectError && res.Data == nil {
 							t.Errorf("Data is nil because of the error: %v", res.Errors)
 							cancel()
+							return
+						}
+
+						eventsReceived++
+						if eventsReceived <= tt.expectedEvents {
+							wg.Done()
 						}
-						wg.Done()
 
 					case <-ctx.Done():
 						return
@@ -139,6 +147,9 @@ func (suite *CommonTestSuite) TestSchemaSubscribe() {
 			}
 
 			wg.Wait()
+			if eventsReceived > tt.expectedEvents {
+				t.Errorf("Received more events than expected. Expected: %d, Got: %d", tt.expectedEvents, eventsReceived)
+			}
 		})
 	}
 }