stackdriver: adds remove group by option

Adds a -- remove group by -- option to the group by
segment. When chosen it removes the group by.

public/app/plugins/datasource/stackdriver/query_ctrl.ts

@@ -67,6 +67,7 @@ export class StackdriverQueryCtrl extends QueryCtrl {
   lastQueryError?: string;
   metricLabels: LabelType[];
   resourceLabels: LabelType[];
+  removeSegment: any;
 
   /** @ngInject */
   constructor($scope, $injector, private uiSegmentSrv, private timeSrv) {
@@ -83,6 +84,7 @@ export class StackdriverQueryCtrl extends QueryCtrl {
     this.groupBySegments = this.target.aggregation.groupBys.map(groupBy => {
       return uiSegmentSrv.getSegmentForValue(groupBy);
     });
+    this.removeSegment = uiSegmentSrv.newSegment({ fake: true, value: '-- remove group by --' });
     this.ensurePlusButton(this.groupBySegments);
   }
 
@@ -174,11 +176,15 @@ export class StackdriverQueryCtrl extends QueryCtrl {
         });
       });
 
-    return Promise.resolve([...metricLabels, ...resourceLabels]);
+    return Promise.resolve([...metricLabels, ...resourceLabels, this.removeSegment]);
   }
 
-  groupByChanged(segment) {
-    segment.type = 'value';
+  groupByChanged(segment, index) {
+    if (segment.value === this.removeSegment.value) {
+      this.groupBySegments.splice(index, 1);
+    } else {
+      segment.type = 'value';
+    }
 
     const reducer = (memo, seg) => {
       if (!seg.fake) {

public/app/plugins/datasource/stackdriver/specs/query_ctrl.test.ts

@@ -17,9 +17,10 @@ describe('StackdriverQueryCtrl', () => {
     });
 
     it('should populate group bys segments', () => {
-      expect(result.length).toBe(2);
+      expect(result.length).toBe(3);
       expect(result[0].value).toBe('metric.label.metric-key-1');
       expect(result[1].value).toBe('resource.label.resource-key-1');
+      expect(result[2].value).toBe('-- remove group by --');
     });
   });
 
@@ -39,16 +40,18 @@ describe('StackdriverQueryCtrl', () => {
     });
 
     it('should not be used to populate group bys segments', () => {
-      expect(result.length).toBe(2);
+      expect(result.length).toBe(3);
       expect(result[0].value).toBe('metric.label.metric-key-2');
       expect(result[1].value).toBe('resource.label.resource-key-2');
+      expect(result[2].value).toBe('-- remove group by --');
     });
   });
 
   describe('when a group by is selected', () => {
     beforeEach(() => {
+      const removeSegment = { fake: true, value: '-- remove group by --' };
       const segment = { value: 'groupby1' };
-      ctrl.groupBySegments = [segment];
+      ctrl.groupBySegments = [segment, removeSegment];
       ctrl.groupByChanged(segment);
     });
 
@@ -56,6 +59,19 @@ describe('StackdriverQueryCtrl', () => {
       expect(ctrl.target.aggregation.groupBys.length).toBe(1);
     });
   });
+
+  describe('when a selected group by is removed', () => {
+    beforeEach(() => {
+      const removeSegment = { fake: true, value: '-- remove group by --' };
+      const segment = { value: 'groupby1' };
+      ctrl.groupBySegments = [segment, removeSegment];
+      ctrl.groupByChanged(removeSegment);
+    });
+
+    it('should be added to group bys list', () => {
+      expect(ctrl.target.aggregation.groupBys.length).toBe(0);
+    });
+  });
 });
 
 function createCtrlWithFakes() {