Original implementation to allow users to subscribe to labels

1. Allow subscribing (the current user) to a label

- Refactor the `Subscription` coffeescript class
  - The main change is that it accepts a container, and conducts all
    DOM queries within its scope. We need this because the labels
    page has multiple instances of `Subscription` on the same page.

2. Creating an issue or MR with labels notifies users subscribed to those labels

- Label `has_many` subscribers through subscriptions.

3. Adding a label to an issue or MR notifies users subscribed to those labels

- This only applies to subscribers of the label that has just been
  added, not all labels for the issue.

2 files changed, 50 insertions, 0 deletions

diff --git a/features/project/labels.feature b/features/project/labels.feature
new file mode 100644
index 00000000000..cd3f3a789f0
--- /dev/null
+++ b/features/project/labels.feature
@@ -0,0 +1,16 @@
+@labels
+Feature: Labels
+  Background:
+    Given I sign in as a user
+    And I own project "Shop"
+    And I visit project "Shop" issues page
+    And project "Shop" has labels: "bug", "feature", "enhancement"
+
+  @javascript
+  Scenario: I can subscribe to a label
+    When I visit project "Shop" labels page
+    Then I should see that I am unsubscribed
+    When I click button "Subscribe"
+    Then I should see that I am subscribed
+    When I click button "Unsubscribe"
+    Then I should see that I am unsubscribed
diff --git a/features/steps/project/labels.rb b/features/steps/project/labels.rb
new file mode 100644
index 00000000000..3f800a10594
--- /dev/null
+++ b/features/steps/project/labels.rb
@@ -0,0 +1,34 @@
+class Spinach::Features::Labels < Spinach::FeatureSteps
+  include SharedAuthentication
+  include SharedIssuable
+  include SharedProject
+  include SharedNote
+  include SharedPaths
+  include SharedMarkdown
+
+  step 'And I visit project "Shop" labels page' do
+    visit namespace_project_labels_path(project.namespace, project)
+  end
+
+  step 'I should see that I am subscribed' do
+    expect(subscribe_button).to have_content 'Unsubscribe'
+  end
+
+  step 'I should see that I am unsubscribed' do
+    expect(subscribe_button).to have_content 'Subscribe'
+  end
+
+  step 'I click button "Unsubscribe"' do
+    subscribe_button.click
+  end
+
+  step 'I click button "Subscribe"' do
+    subscribe_button.click
+  end
+
+  private
+
+  def subscribe_button
+    first('.subscribe-button span')
+  end
+end