SSE: Fix NoData when some series were no data but others not (#45867)

Co-authored-by: Santiago <santiagohernandez.1997@gmail.com>

pkg/expr/classic/classic.go

@@ -129,7 +129,7 @@ func (ccc *ConditionsCmd) Execute(ctx context.Context, vars mathexp.Vars) (mathe
 		}
 
 		thisCondFiring := firingCount > 0
-		thisCondNoData := nilReducedCount > 0
+		thisCondNoData := len(querySeriesSet.Values) == nilReducedCount
 
 		if i == 0 {
 			firing = thisCondFiring
@@ -144,7 +144,7 @@ func (ccc *ConditionsCmd) Execute(ctx context.Context, vars mathexp.Vars) (mathe
 			noDataFound = noDataFound && thisCondNoData
 		}
 
-		if len(querySeriesSet.Values) == nilReducedCount {
+		if thisCondNoData {
 			matches = append(matches, EvalMatch{
 				Metric: "NoData",
 			})

pkg/expr/classic/classic_test.go

@@ -169,6 +169,31 @@ func TestConditionsCmdExecute(t *testing.T) {
 				return v
 			},
 		},
+		{
+			name: "single query and single condition - empty series and not empty series",
+			vars: mathexp.Vars{
+				"A": mathexp.Results{
+					Values: []mathexp.Value{
+						valBasedSeries(),
+						valBasedSeries(ptr.Float64(3)),
+					},
+				},
+			},
+			conditionsCmd: &ConditionsCmd{
+				Conditions: []condition{
+					{
+						QueryRefID: "A",
+						Reducer:    classicReducer("avg"),
+						Operator:   "and",
+						Evaluator:  &thresholdEvaluator{Type: "gt", Threshold: .5},
+					},
+				}},
+			resultNumber: func() mathexp.Number {
+				v := valBasedNumber(ptr.Float64(1))
+				v.SetMeta([]EvalMatch{{Value: ptr.Float64(3)}})
+				return v
+			},
+		},
 		{
 			name: "single query and two conditions",
 			vars: mathexp.Vars{

pkg/expr/classic/reduce_test.go

@@ -102,6 +102,12 @@ func TestReducer(t *testing.T) {
 			inputSeries:    valBasedSeries(nil, nil, ptr.Float64(3), ptr.Float64(4)),
 			expectedNumber: valBasedNumber(ptr.Float64(2)),
 		},
+		{
+			name:           "count_non_null with mixed null/real values",
+			reducer:        classicReducer("count_non_null"),
+			inputSeries:    valBasedSeries(nil, nil, ptr.Float64(3), ptr.Float64(4)),
+			expectedNumber: valBasedNumber(ptr.Float64(2)),
+		},
 		{
 			name:           "count_non_null with no values",
 			reducer:        classicReducer("count_non_null"),