[v10.0.x] Alerting: Sort NumberCaptureValues in EvaluationString

pkg/services/ngalert/eval/extract_md.go

@@ -2,6 +2,7 @@ package eval
 
 import (
 	"fmt"
+	"sort"
 	"strings"
 
 	"github.com/grafana/grafana-plugin-sdk-go/data"
@@ -43,28 +44,27 @@ func extractEvalString(frame *data.Frame) (s string) {
 	}
 
 	if captures, ok := frame.Meta.Custom.([]NumberValueCapture); ok {
+		// Sort captures in ascending order of "Var" so we can assert in tests
+		sort.Slice(captures, func(i, j int) bool {
+			return captures[i].Var < captures[j].Var
+		})
 		sb := strings.Builder{}
-
 		for i, capture := range captures {
 			sb.WriteString("[ ")
 			sb.WriteString(fmt.Sprintf("var='%s' ", capture.Var))
 			sb.WriteString(fmt.Sprintf("labels={%s} ", capture.Labels))
-
 			valString := "null"
 			if capture.Value != nil {
 				valString = fmt.Sprintf("%v", *capture.Value)
 			}
-
 			sb.WriteString(fmt.Sprintf("value=%v ", valString))
-
 			sb.WriteString("]")
 			if i < len(captures)-1 {
 				sb.WriteString(", ")
 			}
 		}
 		return sb.String()
 	}
-
 	return ""
 }
 

pkg/services/ngalert/eval/extract_md_test.go

@@ -40,6 +40,14 @@ func TestExtractEvalString(t *testing.T) {
 			}, util.Pointer(1.0), withRefID("A")),
 			outString: `[ var='A0' metric='Test' labels={host=foo} value=32.3 ], [ var='A1' metric='Test' labels={host=baz} value=10 ], [ var='A2' metric='TestA' labels={host=zip} value=11 ]`,
 		},
+		{
+			desc: "Captures are sorted in ascending order of var",
+			inFrame: newMetaFrame([]NumberValueCapture{
+				{Var: "B", Labels: data.Labels{"host": "foo"}, Value: util.Pointer(1.0)},
+				{Var: "A", Labels: data.Labels{"host": "foo"}, Value: util.Pointer(10.0)},
+			}, util.Pointer(1.0)),
+			outString: `[ var='A' labels={host=foo} value=10 ], [ var='B' labels={host=foo} value=1 ]`,
+		},
 	}
 	for _, tc := range cases {
 		t.Run(tc.desc, func(t *testing.T) {