Continue code quality widget polling while parsing

When the pipeline for an MR is running
or the results are being parsed and compared
the reports response has a 204 (no content) status.
Use pollUntilComplete to keep polling in this case
until we receive either a 200 (ok) status or an error.

Changelog: fixed

app/assets/javascripts/reports/codequality_report/store/actions.js

-import axios from '~/lib/utils/axios_utils';
+import pollUntilComplete from '~/lib/utils/poll_until_complete';
 import * as types from './mutation_types';
 import { parseCodeclimateMetrics } from './utils/codequality_parser';
 
@@ -10,8 +10,7 @@ export const fetchReports = ({ state, dispatch, commit }) => {
   if (!state.basePath) {
     return dispatch('receiveReportsError');
   }
-  return axios
-    .get(state.reportsPath)
+  return pollUntilComplete(state.reportsPath)
     .then(({ data }) => {
       return dispatch('receiveReportsSuccess', {
         newIssues: parseCodeclimateMetrics(data.new_errors, state.headBlobPath),

spec/frontend/reports/codequality_report/store/actions_spec.js

@@ -7,6 +7,11 @@ import * as actions from '~/reports/codequality_report/store/actions';
 import * as types from '~/reports/codequality_report/store/mutation_types';
 import { reportIssues, parsedReportIssues } from '../mock_data';
 
+const pollInterval = 123;
+const pollIntervalHeader = {
+  'Poll-Interval': pollInterval,
+};
+
 describe('Codequality Reports actions', () => {
   let localState;
   let localStore;
@@ -39,10 +44,11 @@ describe('Codequality Reports actions', () => {
   });
 
   describe('fetchReports', () => {
+    const endpoint = `${TEST_HOST}/codequality_reports.json`;
     let mock;
 
     beforeEach(() => {
-      localState.reportsPath = `${TEST_HOST}/codequality_reports.json`;
+      localState.reportsPath = endpoint;
       localState.basePath = '/base/path';
       mock = new MockAdapter(axios);
     });
@@ -53,7 +59,7 @@ describe('Codequality Reports actions', () => {
 
     describe('on success', () => {
       it('commits REQUEST_REPORTS and dispatches receiveReportsSuccess', (done) => {
-        mock.onGet(`${TEST_HOST}/codequality_reports.json`).reply(200, reportIssues);
+        mock.onGet(endpoint).reply(200, reportIssues);
 
         testAction(
           actions.fetchReports,
@@ -73,7 +79,7 @@ describe('Codequality Reports actions', () => {
 
     describe('on error', () => {
       it('commits REQUEST_REPORTS and dispatches receiveReportsError', (done) => {
-        mock.onGet(`${TEST_HOST}/codequality_reports.json`).reply(500);
+        mock.onGet(endpoint).reply(500);
 
         testAction(
           actions.fetchReports,
@@ -100,6 +106,63 @@ describe('Codequality Reports actions', () => {
         );
       });
     });
+
+    describe('while waiting for report results', () => {
+      it('continues polling until it receives data', (done) => {
+        mock
+          .onGet(endpoint)
+          .replyOnce(204, undefined, pollIntervalHeader)
+          .onGet(endpoint)
+          .reply(200, reportIssues);
+
+        Promise.all([
+          testAction(
+            actions.fetchReports,
+            null,
+            localState,
+            [{ type: types.REQUEST_REPORTS }],
+            [
+              {
+                payload: parsedReportIssues,
+                type: 'receiveReportsSuccess',
+              },
+            ],
+            done,
+          ),
+          axios
+            // wait for initial NO_CONTENT response to be fulfilled
+            .waitForAll()
+            .then(() => {
+              jest.advanceTimersByTime(pollInterval);
+            }),
+        ]).catch(done.fail);
+      });
+
+      it('continues polling until it receives an error', (done) => {
+        mock
+          .onGet(endpoint)
+          .replyOnce(204, undefined, pollIntervalHeader)
+          .onGet(endpoint)
+          .reply(500);
+
+        Promise.all([
+          testAction(
+            actions.fetchReports,
+            null,
+            localState,
+            [{ type: types.REQUEST_REPORTS }],
+            [{ type: 'receiveReportsError', payload: expect.any(Error) }],
+            done,
+          ),
+          axios
+            // wait for initial NO_CONTENT response to be fulfilled
+            .waitForAll()
+            .then(() => {
+              jest.advanceTimersByTime(pollInterval);
+            }),
+        ]).catch(done.fail);
+      });
+    });
   });
 
   describe('receiveReportsSuccess', () => {