Merge branch 'disable-calendar-deselection' into 'master'

Fix deselecting calendar days on contribution graph

## What does this MR do?
Fix deselecting calendar days on contribution graph

## Are there points in the code the reviewer needs to double check?
Shouldn't be

## Why was this MR needed?
In `master`, you can currently deselect a calendar day after selecting but you cannot reselect that day.

## Screenshots (if relevant)
Before:
![2016-10-25_10.42.20](/uploads/7d442c09cd15082cf69f673a544b56f9/2016-10-25_10.42.20.gif)

After:
![2016-10-25_10.40.35](/uploads/6123365f0ec63ee84658ee6057e7715c/2016-10-25_10.40.35.gif)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] 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 you do - 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 #22381

See merge request !6453

app/assets/javascripts/users/calendar.js

@@ -206,6 +206,7 @@
           }
         });
       } else {
+        this.currentSelectedDate = '';
         return $('.user-calendar-activities').html('');
       }
     };

changelogs/unreleased/disable-calendar-deselection.yml

+---
+title: Fix deselecting calendar days on contribution graph
+merge_request: 6453
+author: ClemMakesApps

spec/features/calendar_spec.rb

@@ -52,6 +52,10 @@ feature 'Contributions Calendar', js: true, feature: true do
     Event.create(push_params)
   end
 
+  def get_first_cell_content
+    find('.user-calendar-activities').text
+  end
+
   before do
     login_as :user
     visit @user.username
@@ -62,6 +66,43 @@ feature 'Contributions Calendar', js: true, feature: true do
     expect(page).to have_css('.js-contrib-calendar')
   end
 
+  describe 'select calendar day', js: true do
+    let(:cells) { page.all('.user-contrib-cell') }
+    let(:first_cell_content_before) { get_first_cell_content }
+
+    before do
+      cells[0].click
+      wait_for_ajax
+      first_cell_content_before
+    end
+
+    it 'displays calendar day activities', js: true do
+      expect(get_first_cell_content).not_to eq('')
+    end
+
+    describe 'select another calendar day', js: true do
+      before do
+        cells[1].click
+        wait_for_ajax
+      end
+
+      it 'displays different calendar day activities', js: true do
+        expect(get_first_cell_content).not_to eq(first_cell_content_before)
+      end
+    end
+
+    describe 'deselect calendar day', js: true do
+      before do
+        cells[0].click
+        wait_for_ajax
+      end
+
+      it 'hides calendar day activities', js: true do
+        expect(get_first_cell_content).to eq('')
+      end
+    end
+  end
+
   describe '1 calendar activity' do
     before do
       Issues::CreateService.new(contributed_project, @user, issue_params).execute