[v10.0.x] Alerting: Exclude expression refIDs from NoData state (#72394)

* Alerting: Exclude expression refIDs from NoData state (#72219)

(cherry picked from commit 5ba164d)

* use expr.IsDatasource

---------

Co-authored-by: Yuri Tseretyan <yuriy.tseretyan@grafana.com>

pkg/services/ngalert/eval/eval.go

@@ -322,8 +322,6 @@ func queryDataResponseToExecutionResults(c models.Condition, execResp *backend.Q
 	for _, next := range c.Data {
 		datasourceUIDsForRefIDs[next.RefID] = next.DatasourceUID
 	}
-	// datasourceExprUID is a special DatasourceUID for expressions
-	datasourceExprUID := strconv.FormatInt(expr.DatasourceID, 10)
 
 	result := ExecutionResults{Results: make(map[string]data.Frames)}
 	for refID, res := range execResp.Responses {
@@ -345,7 +343,7 @@ func queryDataResponseToExecutionResults(c models.Condition, execResp *backend.Q
 			hasNoFrames := len(res.Frames) == 0
 			hasNoFields := len(res.Frames) == 1 && len(res.Frames[0].Fields) == 0
 			if hasNoFrames || hasNoFields {
-				if s, ok := datasourceUIDsForRefIDs[refID]; ok && s != datasourceExprUID {
+				if s, ok := datasourceUIDsForRefIDs[refID]; ok && !expr.IsDataSource(s) {
 					result.NoData[refID] = s
 				}
 			}

pkg/services/ngalert/eval/eval_test.go

@@ -561,11 +561,19 @@ func TestEvaluate(t *testing.T) {
 			Data: []models.AlertQuery{{
 				RefID:         "A",
 				DatasourceUID: "test",
+			}, {
+				RefID:         "B",
+				DatasourceUID: expr.DatasourceUID,
+			}, {
+				RefID:         "C",
+				DatasourceUID: expr.OldDatasourceUID,
 			}},
 		},
 		resp: backend.QueryDataResponse{
 			Responses: backend.Responses{
 				"A": {Frames: nil},
+				"B": {Frames: []*data.Frame{{Fields: nil}}},
+				"C": {Frames: nil},
 			},
 		},
 		expected: Results{{