Add column chart component to the monitoring bundle

This merge request just adds the column chart
component without integrating it to the dashboard

app/assets/javascripts/monitoring/components/charts/column.vue

+<script>
+import { GlColumnChart } from '@gitlab/ui/dist/charts';
+import { debounceByAnimationFrame } from '~/lib/utils/common_utils';
+import { getSvgIconPathContent } from '~/lib/utils/icon_utils';
+import { chartHeight } from '../../constants';
+import { makeDataSeries } from '~/helpers/monitor_helper';
+
+export default {
+  components: {
+    GlColumnChart,
+  },
+  inheritAttrs: false,
+  props: {
+    graphData: {
+      type: Object,
+      required: true,
+      validator(data) {
+        return (
+          Array.isArray(data.queries) &&
+          data.queries.filter(query => {
+            if (Array.isArray(query.result)) {
+              return (
+                query.result.filter(res => Array.isArray(res.values)).length === query.result.length
+              );
+            }
+            return false;
+          }).length === data.queries.length
+        );
+      },
+      containerWidth: {
+        type: Number,
+        required: true,
+      },
+    },
+  },
+  data() {
+    return {
+      width: 0,
+      height: chartHeight,
+      svgs: {},
+      debouncedResizeCallback: {},
+    };
+  },
+  computed: {
+    chartData() {
+      const queryData = this.graphData.queries.reduce((acc, query) => {
+        const series = makeDataSeries(query.result, {
+          name: this.formatLegendLabel(query),
+        });
+
+        return acc.concat(series);
+      }, []);
+
+      return {
+        values: queryData[0].data,
+      };
+    },
+    xAxisTitle() {
+      return this.graphData.queries[0].result[0].x_label !== undefined
+        ? this.graphData.queries[0].result[0].x_label
+        : '';
+    },
+    yAxisTitle() {
+      return this.graphData.queries[0].result[0].y_label !== undefined
+        ? this.graphData.queries[0].result[0].y_label
+        : '';
+    },
+    xAxisType() {
+      return this.graphData.x_type !== undefined ? this.graphData.x_type : 'category';
+    },
+    dataZoomConfig() {
+      const handleIcon = this.svgs['scroll-handle'];
+
+      return handleIcon ? { handleIcon } : {};
+    },
+    chartOptions() {
+      return {
+        dataZoom: this.dataZoomConfig,
+      };
+    },
+  },
+  watch: {
+    containerWidth: 'onResize',
+  },
+  beforeDestroy() {
+    window.removeEventListener('resize', this.debouncedResizeCallback);
+  },
+  created() {
+    this.debouncedResizeCallback = debounceByAnimationFrame(this.onResize);
+    window.addEventListener('resize', this.debouncedResizeCallback);
+    this.setSvg('scroll-handle');
+  },
+  methods: {
+    formatLegendLabel(query) {
+      return `${query.label}`;
+    },
+    onResize() {
+      const { width } = this.$refs.columnChart.$el.getBoundingClientRect();
+      this.width = width;
+    },
+    setSvg(name) {
+      getSvgIconPathContent(name)
+        .then(path => {
+          if (path) {
+            this.$set(this.svgs, name, `path://${path}`);
+          }
+        })
+        .catch(() => {});
+    },
+  },
+};
+</script>
+<template>
+  <div class="prometheus-graph col-12 col-lg-6">
+    <div class="prometheus-graph-header">
+      <h5 ref="graphTitle" class="prometheus-graph-title">{{ graphData.title }}</h5>
+      <div ref="graphWidgets" class="prometheus-graph-widgets"><slot></slot></div>
+    </div>
+    <gl-column-chart
+      ref="columnChart"
+      v-bind="$attrs"
+      :data="chartData"
+      :option="chartOptions"
+      :width="width"
+      :height="height"
+      :x-axis-title="xAxisTitle"
+      :y-axis-title="yAxisTitle"
+      :x-axis-type="xAxisType"
+    />
+  </div>
+</template>

spec/javascripts/monitoring/charts/column_spec.js

+import { shallowMount } from '@vue/test-utils';
+import { GlColumnChart } from '@gitlab/ui/dist/charts';
+import ColumnChart from '~/monitoring/components/charts/column.vue';
+
+describe('Column component', () => {
+  let columnChart;
+
+  beforeEach(() => {
+    columnChart = shallowMount(ColumnChart, {
+      propsData: {
+        graphData: {
+          queries: [
+            {
+              x_label: 'Time',
+              y_label: 'Usage',
+              result: [
+                {
+                  metric: {},
+                  values: [
+                    [1495700554.925, '8.0390625'],
+                    [1495700614.925, '8.0390625'],
+                    [1495700674.925, '8.0390625'],
+                  ],
+                },
+              ],
+            },
+          ],
+        },
+        containerWidth: 100,
+      },
+    });
+  });
+
+  afterEach(() => {
+    columnChart.destroy();
+  });
+
+  describe('wrapped components', () => {
+    describe('GitLab UI column chart', () => {
+      let glColumnChart;
+
+      beforeEach(() => {
+        glColumnChart = columnChart.find(GlColumnChart);
+      });
+
+      it('is a Vue instance', () => {
+        expect(glColumnChart.isVueInstance()).toBe(true);
+      });
+
+      it('receives data properties needed for proper chart render', () => {
+        const props = glColumnChart.props();
+
+        expect(props.data).toBe(columnChart.vm.chartData);
+        expect(props.option).toBe(columnChart.vm.chartOptions);
+      });
+    });
+  });
+});