feat(test metrics): fixed issue with built in Grafana test data source, fixes grafana#5299

Author: torkelo

pkg/api/metrics.go

@@ -12,7 +12,7 @@ import (
 	"github.com/grafana/grafana/pkg/util"
 )
 
-func GetTestMetrics(c *middleware.Context) {
+func GetTestMetrics(c *middleware.Context) Response {
 	from := c.QueryInt64("from")
 	to := c.QueryInt64("to")
 	maxDataPoints := c.QueryInt64("maxDataPoints")
@@ -37,7 +37,7 @@ func GetTestMetrics(c *middleware.Context) {
 		result.Data[seriesIndex].DataPoints = points
 	}
 
-	c.JSON(200, &result)
+	return Json(200, &result)
 }
 
 func GetInternalMetrics(c *middleware.Context) Response {

public/app/features/panel/metrics_panel_ctrl.ts

@@ -200,6 +200,11 @@ class MetricsPanelCtrl extends PanelCtrl {
       this.panel.snapshotData = result.data;
     }
 
+    if (!result || !result.data) {
+      console.log('Data source query result invalid, missing data field:', result);
+      result = {data: []};
+    }
+
     return this.events.emit('data-received', result.data);
   }