Added test for the chart legend

changelogs/unreleased/34655-label-field-for-setting-a-chart-s-legend-text-is-not-working.yml

+---
+title: Fixed the chart legend not being set correctly
+merge_request: 12628
+author:

spec/javascripts/monitoring/mock_data.js

@@ -2481,6 +2481,7 @@ export const singleRowMetrics = [
     'queries': [
       {
         'query_range': 'avg(rate(container_cpu_usage_seconds_total{%{environment_filter}}[2m])) * 100',
+        'label': 'Container CPU',
         'result': [
           {
             'metric': {

spec/javascripts/monitoring/monitoring_column_spec.js

@@ -95,7 +95,7 @@ describe('MonitoringColumn', () => {
     });
   });
 
-  it('has a title for the y-axis that comes from the backend', () => {
+  it('has a title for the y-axis and the chart legend that comes from the backend', () => {
     const component = createComponent({
       columnData: singleRowMetrics[0],
       classType: 'col-md-6',
@@ -104,5 +104,6 @@ describe('MonitoringColumn', () => {
     });
 
     expect(component.yAxisLabel).toEqual(component.columnData.y_label);
+    expect(component.legendTitle).toEqual(component.columnData.queries[0].label);
   });
 });