Alerting: Display query from grafana-managed alert rules on /api/v1/rules (#45969)

* Aleting: Extract query from alerting rule model for api/v1/rules

* more changes and fixtures

* appease the linter

pkg/services/ngalert/models/alert_query_test.go

@@ -2,6 +2,7 @@ package models
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"testing"
 	"time"
@@ -110,7 +111,7 @@ func TestAlertQuery(t *testing.T) {
 				Model: json.RawMessage(`{
 					"queryType": "metricQuery",
 					"intervalMs": "invalid",
-					"extraParam": "some text"	
+					"extraParam": "some text"
 				}`),
 			},
 			expectedIsExpression: false,
@@ -245,3 +246,38 @@ func TestAlertQueryMarshalling(t *testing.T) {
 		}
 	}
 }
+
+func TestAlertQuery_GetQuery(t *testing.T) {
+	tc := []struct {
+		name       string
+		alertQuery AlertQuery
+		expected   string
+		err        error
+	}{
+		{
+			name:       "when a query is present",
+			alertQuery: AlertQuery{Model: json.RawMessage(`{"expr": "sum by (job) (up)"}`)},
+			expected:   "sum by (job) (up)",
+		},
+		{
+			name:       "when no query is found",
+			alertQuery: AlertQuery{Model: json.RawMessage(`{"exprisnot": "sum by (job) (up)"}`)},
+			err:        ErrNoQuery,
+		},
+		{
+			name:       "when we're unable to cast the query to a string",
+			alertQuery: AlertQuery{Model: json.RawMessage(`{"expr": {"key": 1}}`)},
+			err:        errors.New("failed to cast query to string: map[key:1]"),
+		},
+	}
+
+	for _, tt := range tc {
+		t.Run(tt.name, func(t *testing.T) {
+			expected, err := tt.alertQuery.GetQuery()
+			if err != nil {
+				require.Equal(t, tt.err, err)
+			}
+			require.Equal(t, tt.expected, expected)
+		})
+	}
+}