Alerting: Add QueryError to expr package (grafana#41737)

pkg/expr/nodes.go

@@ -19,6 +19,15 @@ var (
  logger = log.New("expr")
 )
 
+type QueryError struct {
+ RefID string
+ Err error
+}
+
+func (e QueryError) Error() string {
+ return fmt.Sprintf("failed to execute query %s: %s", e.RefID, e.Err)
+}
+
 // baseNode includes common properties used across DPNodes.
 type baseNode struct {
  id int64
@@ -240,7 +249,7 @@ func (dn *DSNode) Execute(ctx context.Context, vars mathexp.Vars, s *Service) (m
  vals := make([]mathexp.Value, 0)
  for refID, qr := range resp.Responses {
  if qr.Error != nil {
- return mathexp.Results{}, fmt.Errorf("failed to execute query %v: %w", refID, qr.Error)
+ return mathexp.Results{}, QueryError{RefID: refID, Err: qr.Error}
  }
 
  if len(qr.Frames) == 1 {

pkg/expr/nodes_test.go

@@ -0,0 +1,16 @@
+package expr
+
+import (
+ "errors"
+ "testing"
+
+ "github.com/stretchr/testify/assert"
+)
+
+func TestQueryError(t *testing.T) {
+ e := QueryError{
+ RefID: "A",
+ Err: errors.New("this is an error message"),
+ }
+ assert.EqualError(t, e, "failed to execute query A: this is an error message")
+}