[SIP-5] Build metrics in query_object in the client (#6423)

* [SIP-5] Build metrics in query_object in the client
- Unify the metric interface (absorb the current plain string metric for built-in metric keys into the format used by adhoc metric)
- Port the logic in adhocMetric on the client and process_metrics in the backend to the new typed Metrics class
- Omit hasCustomLabel and formFromData properties from the new metric interface as their value can be inferred from label and optionName
- Expose from the Metrics class both metrics and their labels as public methods to match the all_metrics and metric_labels fields in the backend code
- Provide defaut values for filters, metrics and groupby in the backend

* addressing PR comments

* Adding a comment for metrictype values

superset/assets/spec/javascripts/superset-ui/Metric.test.ts

@@ -0,0 +1,95 @@
+import { ColumnType } from 'src/query/Column';
+import {
+  AdhocMetric, Aggregate, ExpressionType, LABEL_MAX_LENGTH, Metrics,
+} from 'src/query/Metric';
+
+describe('Metrics', () => {
+  let metrics: Metrics;
+  const formData = {
+    datasource: '5__table',
+    granularity_sqla: 'ds',
+  };
+
+  it('should build metrics for built-in metric keys', () => {
+    metrics = new Metrics({
+      ...formData,
+      metric: 'sum__num',
+    });
+    expect(metrics.getMetrics()).toEqual([{label: 'sum__num'}]);
+    expect(metrics.getLabels()).toEqual(['sum__num']);
+  });
+
+  it('should build metrics for simple adhoc metrics', () => {
+    const adhocMetric: AdhocMetric = {
+      aggregate: Aggregate.AVG,
+      column: {
+        columnName: 'sum_girls',
+        id: 5,
+        type: ColumnType.BIGINT,
+      },
+      expressionType: ExpressionType.SIMPLE,
+    };
+    metrics = new Metrics({
+      ...formData,
+      metric: adhocMetric,
+    });
+    expect(metrics.getMetrics()).toEqual([{
+      aggregate: 'AVG',
+      column: {
+        columnName: 'sum_girls',
+        id: 5,
+        type: ColumnType.BIGINT,
+      },
+      expressionType: 'SIMPLE',
+      label: 'AVG(sum_girls)',
+    }]);
+    expect(metrics.getLabels()).toEqual(['AVG(sum_girls)']);
+  });
+
+  it('should build metrics for SQL adhoc metrics', () => {
+    const adhocMetric: AdhocMetric = {
+      expressionType: ExpressionType.SQL,
+      sqlExpression: 'COUNT(sum_girls)',
+    };
+    metrics = new Metrics({
+      ...formData,
+      metric: adhocMetric,
+    });
+    expect(metrics.getMetrics()).toEqual([{
+      expressionType: 'SQL',
+      label: 'COUNT(sum_girls)',
+      sqlExpression: 'COUNT(sum_girls)',
+    }]);
+    expect(metrics.getLabels()).toEqual(['COUNT(sum_girls)']);
+  });
+
+  it('should build metrics for adhoc metrics with custom labels', () => {
+    const adhocMetric: AdhocMetric = {
+      expressionType: ExpressionType.SQL,
+      label: 'foo',
+      sqlExpression: 'COUNT(sum_girls)',
+    };
+    metrics = new Metrics({
+      ...formData,
+      metric: adhocMetric,
+    });
+    expect(metrics.getMetrics()).toEqual([{
+      expressionType: 'SQL',
+      label: 'foo',
+      sqlExpression: 'COUNT(sum_girls)',
+    }]);
+    expect(metrics.getLabels()).toEqual(['foo']);
+  });
+
+  it('should truncate labels if they are too long', () => {
+    const adhocMetric: AdhocMetric = {
+      expressionType: ExpressionType.SQL,
+      sqlExpression: 'COUNT(verrrrrrrrry_loooooooooooooooooooooong_string)',
+    };
+    metrics = new Metrics({
+      ...formData,
+      metric: adhocMetric,
+    });
+    expect(metrics.getLabels()[0].length).toBeLessThanOrEqual(LABEL_MAX_LENGTH);
+  });
+});

superset/assets/spec/javascripts/superset-ui/buildQueryObject.test.ts

@@ -1,13 +1,24 @@
-import build from 'src/query/buildQueryObject';
+import build, { QueryObject } from 'src/query/buildQueryObject';
 
 describe('queryObjectBuilder', () => {
+  let query: QueryObject;
+
   it('should build granularity for sql alchemy datasources', () => {
-    const query = build({datasource: '5__table', granularity_sqla: 'ds'});
+    query = build({datasource: '5__table', granularity_sqla: 'ds'});
     expect(query.granularity).toEqual('ds');
   });
 
-  it('should build granularity for sql alchemy datasources', () => {
-    const query = build({datasource: '5__druid', granularity: 'ds'});
+  it('should build granularity for sql druid datasources', () => {
+    query = build({datasource: '5__druid', granularity: 'ds'});
     expect(query.granularity).toEqual('ds');
   });
+
+  it('should build metrics', () => {
+    query = build({
+      datasource: '5__table',
+      granularity_sqla: 'ds',
+      metric: 'sum__num',
+    });
+    expect(query.metrics).toEqual([{label: 'sum__num'}]);
+  });
 });