Merge branch '25483-broken-tabs' into 'master'

Fix TypeError: Cannot read property 'initTabs'

## What does this MR do?
Adds a default value to the `options` argument in order to prevent errors when `Pipelines` is initialised without arguments.
Adds tests to guarantee this does not happen again.

Adds back removed pipeline class to make the pipeline graph visible, `js-pipeline-graph`

## Why was this MR needed?
In the places where `Pipelines` is initialised without arguments it throws an error: `TypeError: Cannot read property 'initTabs'`


## Does this MR meet the acceptance criteria?
- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?
Closes #25483 
Closes #25493 

See merge request !8009

1 files changed, 7 insertions, 4 deletions

diff --git a/app/assets/javascripts/pipelines.js.es6 b/app/assets/javascripts/pipelines.js.es6
index 72c6c4a1fcd..fb95648e1c7 100644
--- a/app/assets/javascripts/pipelines.js.es6
+++ b/app/assets/javascripts/pipelines.js.es6
@@ -4,7 +4,7 @@
 ((global) => {
 
   class Pipelines {
-    constructor(options) {
+    constructor(options = {}) {
 
       if (options.initTabs && options.tabsOptions) {
         new global.LinkedTabs(options.tabsOptions);
@@ -14,9 +14,11 @@
     }
 
     addMarginToBuildColumns() {
-      this.pipelineGraph = document.querySelector('.pipeline-graph');
-      const secondChildBuildNodes = document.querySelector('.pipeline-graph').querySelectorAll('.build:nth-child(2)');
-      for (buildNodeIndex in secondChildBuildNodes) {
+      this.pipelineGraph = document.querySelector('.js-pipeline-graph');
+
+      const secondChildBuildNodes = this.pipelineGraph.querySelectorAll('.build:nth-child(2)');
+
+      for (const buildNodeIndex in secondChildBuildNodes) {
         const buildNode = secondChildBuildNodes[buildNodeIndex];
         const firstChildBuildNode = buildNode.previousElementSibling;
         if (!firstChildBuildNode || !firstChildBuildNode.matches('.build')) continue;
@@ -28,6 +30,7 @@
         const columnBuilds = previousColumn.querySelectorAll('.build');
         if (columnBuilds.length === 1) previousColumn.classList.add('no-margin');
       }
+
       this.pipelineGraph.classList.remove('hidden');
     }
   }