Reset container width when switching to pipelines MR tab

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/29539

app/assets/javascripts/merge_request_tabs.js

@@ -131,12 +131,8 @@ require('./flash');
           offset: 0,
         });
       } else if (action === 'pipelines') {
-        if (this.pipelinesLoaded) {
-          return;
-        }
-        const pipelineTableViewEl = document.querySelector('#commit-pipeline-table-view');
-        gl.commits.pipelines.PipelinesTableBundle.$mount(pipelineTableViewEl);
-        this.pipelinesLoaded = true;
+        this.resetViewContainer();
+        this.loadPipelines();
       } else {
         this.expandView();
         this.resetViewContainer();
@@ -225,6 +221,15 @@ require('./flash');
       });
     }
+    loadPipelines() {
+      if (this.pipelinesLoaded) {
+        return;
+      }
+      const pipelineTableViewEl = document.querySelector('#commit-pipeline-table-view');
+      gl.commits.pipelines.PipelinesTableBundle.$mount(pipelineTableViewEl);
+      this.pipelinesLoaded = true;
+    }
+
     loadDiff(source) {
       if (this.diffsLoaded) {
         return;

lib/tasks/karma.rake

 unless Rails.env.production?
   namespace :karma do
     desc 'GitLab | Karma | Generate fixtures for JavaScript tests'
-    RSpec::Core::RakeTask.new(:fixtures) do |t|
+    RSpec::Core::RakeTask.new(:fixtures, [:pattern]) do |t, args|
+      args.with_defaults(pattern: 'spec/javascripts/fixtures/*.rb')
       ENV['NO_KNAPSACK'] = 'true'
-      t.pattern = 'spec/javascripts/fixtures/*.rb'
+      t.pattern = args[:pattern]
       t.rspec_opts = '--format documentation'
     end

spec/javascripts/fixtures/merge_requests.rb

@@ -6,6 +6,15 @@ describe Projects::MergeRequestsController, '(JavaScript fixtures)', type: :cont
   let(:admin) { create(:admin) }
   let(:namespace) { create(:namespace, name: 'frontend-fixtures' )}
   let(:project) { create(:project, namespace: namespace, path: 'merge-requests-project') }
+  let(:merge_request) { create(:merge_request, :with_diffs, source_project: project, target_project: project, description: '- [ ] Task List Item') }
+  let(:pipeline) do
+    create(
+      :ci_pipeline,
+      project: merge_request.source_project,
+      ref: merge_request.source_branch,
+      sha: merge_request.diff_head_sha
+    )
+  end
   render_views
@@ -18,7 +27,8 @@ describe Projects::MergeRequestsController, '(JavaScript fixtures)', type: :cont
   end
   it 'merge_requests/merge_request_with_task_list.html.raw' do |example|
-    merge_request = create(:merge_request, :with_diffs, source_project: project, target_project: project, description: '- [ ] Task List Item')
+    create(:ci_build, :pending, pipeline: pipeline)
+
     render_merge_request(example.description, merge_request)
   end

spec/javascripts/merge_request_tabs_spec.js

@@ -3,6 +3,7 @@
 require('~/merge_request_tabs');
 require('~/breakpoints');
 require('~/lib/utils/common_utils');
+require('~/commit/pipelines/pipelines_bundle');
 require('vendor/jquery.scrollTo');
 (function () {
@@ -200,6 +201,42 @@ require('vendor/jquery.scrollTo');
         expect(this.subject('show')).toBe('/foo/bar/merge_requests/1');
       });
     });
+
+    describe('#tabShown', () => {
+      beforeEach(function () {
+        loadFixtures('merge_requests/merge_request_with_task_list.html.raw');
+      });
+
+      describe('with "Side-by-side"/parallel diff view', () => {
+        beforeEach(function () {
+          this.class.diffViewType = () => 'parallel';
+        });
+
+        fit('maintains `container-limited` for pipelines tab', function (done) {
+          const asyncClick = function (selector) {
+            return new Promise((resolve) => {
+              setTimeout(() => {
+                document.querySelector(selector).click();
+                resolve();
+              });
+            });
+          };
+
+          asyncClick('.merge-request-tabs .pipelines-tab a')
+            .then(() => asyncClick('.merge-request-tabs .diffs-tab a'))
+            .then(() => asyncClick('.merge-request-tabs .pipelines-tab a'))
+            .then(() => {
+              const hasContainerLimitedClass = document.querySelector('.content-wrapper .container-fluid').classList.contains('container-limited');
+              expect(hasContainerLimitedClass).toBe(true);
+            })
+            .then(done)
+            .catch((err) => {
+              done.fail(`Something went wrong clicking MR tabs: ${err.message}\n${err.stack}`);
+            });
+        });
+      });
+    });
+
     describe('#loadDiff', function () {
       it('requires an absolute pathname', function () {
         spyOn($, 'ajax').and.callFake(function (options) {