Merge branch 'merge-if-green' into 'master'

Merge when build succeeds

### What does this MR do?
Adds a button to a MR when the build/ci is running so it can be merged when/if the build is successfull.

### Are there points in the code the reviewer needs to double check?
English spelling and whether or not the grammer is correct.

### Why was this MR needed?
When you expect its all good, and don't want to revisit the current MR it can be accepted allready.

### What are the relevant issue numbers / Feature requests?
Fixes #2640 -- although `Merge if green` is replaced with `Merge when the build succeeds` the general idea is the same.

### Screenshots (if relevant)
![Screenshot_from_2015-12-07_10-34-39](/uploads/b90b558b6ad6c8266bc9c96120d86f96/Screenshot_from_2015-12-07_10-34-39.png)

![Screenshot_from_2015-11-02_17-26-56](/uploads/9f52f56e3c5e9ec63cb8f42978c92a52/Screenshot_from_2015-11-02_17-26-56.png)
![Screenshot_from_2015-11-02_17-27-03](/uploads/119fc18c9b15ff73dc38010ac5b6244a/Screenshot_from_2015-11-02_17-27-03.png)

![Screenshot_from_2015-12-03_10-08-14](/uploads/bad7b35c7d129981d43631877c958be0/Screenshot_from_2015-12-03_10-08-14.png)

![Screenshot_from_2015-11-02_17-27-16](/uploads/b616d750a16cc11ba72f2ca84213515e/Screenshot_from_2015-11-02_17-27-16.png)

### Further considerations
What if there are minor things needed solving, e.g. Rubocop, the current implementation will reset the approved status of the MR. It might be a consideration keep the approval for team member, or even guests. This would require an extra option in the Admin screen, though might add extra value.

#### TODO
- [x] Docs
- [x] Specs

/cc @DouweM @rspeicher

See merge request !1729

CHANGELOG

@@ -1,6 +1,7 @@
 Please view this file on the master branch, on stable branches it's out of date.
 
 v 8.3.0 (unreleased)
+  - Merge when build succeeds (Zeger-Jan van de Weg)
   - Bump gollum-lib to 4.1.0 (Stan Hu)
   - Fix broken group avatar upload under "New group" (Stan Hu)
   - Update project repositorize size and commit count during import:repos task (Stan Hu)

app/assets/stylesheets/pages/merge_requests.scss

@@ -18,6 +18,7 @@
   .accept-merge-holder {
     .accept-action {
       display: inline-block;
+      float: left;
 
       .accept_merge_request {
         &.ci-pending,
@@ -36,14 +37,15 @@
 
     .accept-control {
       display: inline-block;
+      float: left;
       margin: 0;
       margin-left: 20px;
       padding: 5px;
+      padding-top: 12px;
       line-height: 20px;
 
       &.right {
         float: right;
-        padding-top: 12px;
         a {
           color: $gl-gray;
         }

app/controllers/projects/merge_requests_controller.rb

@@ -2,11 +2,12 @@ class Projects::MergeRequestsController < Projects::ApplicationController
   before_action :module_enabled
   before_action :merge_request, only: [
     :edit, :update, :show, :diffs, :commits, :builds, :merge, :merge_check,
-    :ci_status, :toggle_subscription
+    :ci_status, :toggle_subscription, :cancel_merge_when_build_succeeds
   ]
   before_action :closes_issues, only: [:edit, :update, :show, :diffs, :commits, :builds]
   before_action :validates_merge_request, only: [:show, :diffs, :commits, :builds]
   before_action :define_show_vars, only: [:show, :diffs, :commits, :builds]
+  before_action :define_widget_vars, only: [:merge, :cancel_merge_when_build_succeeds]
   before_action :ensure_ref_fetched, only: [:show, :diffs, :commits, :builds]
 
   # Allow read any merge_request
@@ -164,15 +165,29 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     render partial: "projects/merge_requests/widget/show.html.haml", layout: false
   end
 
+  def cancel_merge_when_build_succeeds
+    return access_denied! unless @merge_request.can_cancel_merge_when_build_succeeds?(current_user)
+
+    MergeRequests::MergeWhenBuildSucceedsService.new(@project, current_user).cancel(@merge_request)
+  end
+
   def merge
     return access_denied! unless @merge_request.can_be_merged_by?(current_user)
 
-    if @merge_request.mergeable?
-      @merge_request.update(merge_error: nil)
-      MergeWorker.perform_async(@merge_request.id, current_user.id, params)
-      @status = true
+    unless @merge_request.mergeable?
+      @status = :failed
+      return
+    end
+
+    @merge_request.update(merge_error: nil)
+
+    if params[:merge_when_build_succeeds] && @merge_request.ci_commit && @merge_request.ci_commit.active?
+      MergeRequests::MergeWhenBuildSucceedsService.new(@project, current_user, merge_params)
+                                                      .execute(@merge_request)
+      @status = :merge_when_build_succeeds
     else
-      @status = false
+      MergeWorker.perform_async(@merge_request.id, current_user.id, params)
+      @status = :success
     end
   end
 
@@ -287,6 +302,10 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     end
   end
 
+  def define_widget_vars
+    @ci_commit = @merge_request.ci_commit
+  end
+
   def invalid_mr
     # Render special view for MR with removed source or target branch
     render 'invalid'
@@ -300,6 +319,10 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     )
   end
 
+  def merge_params
+    params.permit(:should_remove_source_branch, :commit_message)
+  end
+
   # Make sure merge requests created before 8.0
   # have head file in refs/merge-requests/
   def ensure_ref_fetched

app/models/ci/commit.rb

@@ -165,6 +165,14 @@ module Ci
       status == 'canceled'
     end
 
+    def active?
+      running? || pending?
+    end
+
+    def complete?
+      canceled? || success? || failed?
+    end
+
     def duration
       duration_array = latest_statuses.map(&:duration).compact
       duration_array.reduce(:+).to_i

app/models/commit_status.rb

@@ -1,34 +1,30 @@
 # == Schema Information
 #
-# Table name: ci_builds
-#
-#  id                 :integer          not null, primary key
-#  project_id         :integer
-#  status             :string(255)
-#  finished_at        :datetime
-#  trace              :text
-#  created_at         :datetime
-#  updated_at         :datetime
-#  started_at         :datetime
-#  runner_id          :integer
-#  coverage           :float
-#  commit_id          :integer
-#  commands           :text
-#  job_id             :integer
-#  name               :string(255)
-#  deploy             :boolean          default(FALSE)
-#  options            :text
-#  allow_failure      :boolean          default(FALSE), not null
-#  stage              :string(255)
-#  trigger_request_id :integer
-#  stage_idx          :integer
-#  tag                :boolean
-#  ref                :string(255)
-#  user_id            :integer
-#  type               :string(255)
-#  target_url         :string(255)
-#  description        :string(255)
-#  artifacts_file     :text
+#  project_id            integer
+#  status                string
+#  finished_at           datetime
+#  trace                 text
+#  created_at            datetime
+#  updated_at            datetime
+#  started_at            datetime
+#  runner_id             integer
+#  coverage              float
+#  commit_id             integer
+#  commands              text
+#  job_id                integer
+#  name                  string
+#  deploy                boolean           default: false
+#  options               text
+#  allow_failure         boolean           default: false, null: false
+#  stage                 string
+#  trigger_request_id    integer
+#  stage_idx             integer
+#  tag                   boolean
+#  ref                   string
+#  user_id               integer
+#  type                  string
+#  target_url            string
+#  description           string
 #
 
 class CommitStatus < ActiveRecord::Base
@@ -79,6 +75,10 @@ class CommitStatus < ActiveRecord::Base
       build.update_attributes finished_at: Time.now
     end
 
+    after_transition [:pending, :running] => :success do |build, transition|
+      MergeRequests::MergeWhenBuildSucceedsService.new(build.commit.gl_project, nil).trigger(build)
+    end
+
     state :pending, value: 'pending'
     state :running, value: 'running'
     state :failed, value: 'failed'

app/models/merge_request.rb

@@ -2,25 +2,28 @@
 #
 # Table name: merge_requests
 #
-#  id                :integer          not null, primary key
-#  target_branch     :string(255)      not null
-#  source_branch     :string(255)      not null
-#  source_project_id :integer          not null
-#  author_id         :integer
-#  assignee_id       :integer
-#  title             :string(255)
-#  created_at        :datetime
-#  updated_at        :datetime
-#  milestone_id      :integer
-#  state             :string(255)
-#  merge_status      :string(255)
-#  target_project_id :integer          not null
-#  iid               :integer
-#  description       :text
-#  position          :integer          default(0)
-#  locked_at         :datetime
-#  updated_by_id     :integer
-#  merge_error       :string(255)
+#  id                         :integer          not null, primary key
+#  target_branch              :string(255)      not null
+#  source_branch              :string(255)      not null
+#  source_project_id          :integer          not null
+#  author_id                  :integer
+#  assignee_id                :integer
+#  title                      :string(255)
+#  created_at                 :datetime
+#  updated_at                 :datetime
+#  milestone_id               :integer
+#  state                      :string(255)
+#  merge_status               :string(255)
+#  target_project_id          :integer          not null
+#  iid                        :integer
+#  description                :text
+#  position                   :integer          default(0)
+#  locked_at                  :datetime
+#  updated_by_id              :integer
+#  merge_error                :string(255)
+#  merge_params               :text (serialized to hash)
+#  merge_when_build_succeeds  :boolean          default(false), not null
+#  merge_user_id              :integer
 #
 
 require Rails.root.join("app/models/commit")
@@ -35,9 +38,12 @@ class MergeRequest < ActiveRecord::Base
 
   belongs_to :target_project, foreign_key: :target_project_id, class_name: "Project"
   belongs_to :source_project, foreign_key: :source_project_id, class_name: "Project"
+  belongs_to :merge_user, class_name: "User"
 
   has_one :merge_request_diff, dependent: :destroy
 
+  serialize :merge_params, Hash
+
   after_create :create_merge_request_diff
   after_update :update_merge_request_diff
 
@@ -121,6 +127,7 @@ class MergeRequest < ActiveRecord::Base
   validates :source_branch, presence: true
   validates :target_project, presence: true
   validates :target_branch, presence: true
+  validates :merge_user, presence: true, if: :merge_when_build_succeeds?
   validate :validate_branches
   validate :validate_fork
 
@@ -258,6 +265,16 @@ class MergeRequest < ActiveRecord::Base
     end
   end
 
+  def can_cancel_merge_when_build_succeeds?(current_user)
+    can_be_merged_by?(current_user) || self.author == current_user
+  end
+
+  def can_remove_source_branch?(current_user)
+    !source_project.protected_branch?(source_branch) &&
+      !source_project.root_ref?(source_branch) &&
+      Ability.abilities.allowed?(current_user, :push_code, source_project)
+  end
+
   def mr_and_commit_notes
     # Fetch comments only from last 100 commits
     commits_for_notes_limit = 100
@@ -393,6 +410,16 @@ class MergeRequest < ActiveRecord::Base
     message
   end
 
+  def reset_merge_when_build_succeeds
+    return unless merge_when_build_succeeds?
+
+    self.merge_when_build_succeeds = false
+    self.merge_user = nil
+    self.merge_params = nil
+
+    self.save
+  end
+
   # Return array of possible target branches
   # depends on target project of MR
   def target_branches
@@ -480,8 +507,6 @@ class MergeRequest < ActiveRecord::Base
   end
 
   def ci_commit
-    if last_commit and source_project
-      source_project.ci_commit(last_commit.id)
-    end
+    @ci_commit ||= source_project.ci_commit(last_commit.id) if last_commit && source_project
   end
 end

app/services/merge_requests/merge_service.rb

@@ -6,15 +6,12 @@ module MergeRequests
   # Executed when you do merge via GitLab UI
   #
   class MergeService < MergeRequests::BaseService
-    attr_reader :merge_request, :commit_message
+    attr_reader :merge_request
 
-    def execute(merge_request, commit_message)
-      @commit_message = commit_message
+    def execute(merge_request)
       @merge_request = merge_request
 
-      unless @merge_request.mergeable?
-        return error('Merge request is not mergeable')
-      end
+      return error('Merge request is not mergeable') unless @merge_request.mergeable?
 
       merge_request.in_locked_state do
         if commit
@@ -32,7 +29,7 @@ module MergeRequests
       committer = repository.user_to_committer(current_user)
 
       options = {
-        message: commit_message,
+        message: params[:commit_message] || merge_request.merge_commit_message,
         author: committer,
         committer: committer
       }
@@ -46,6 +43,11 @@ module MergeRequests
 
     def after_merge
       MergeRequests::PostMergeService.new(project, current_user).execute(merge_request)
+
+      if params[:should_remove_source_branch]
+        DeleteBranchService.new(@merge_request.source_project, current_user).
+          execute(merge_request.source_branch)
+      end
     end
   end
 end

app/services/merge_requests/merge_when_build_succeeds_service.rb

@@ -0,0 +1,55 @@
+module MergeRequests
+  class MergeWhenBuildSucceedsService < MergeRequests::BaseService
+    # Marks the passed `merge_request` to be merged when the build succeeds or
+    # updates the params for the automatic merge
+    def execute(merge_request)
+      merge_request.merge_params.merge!(params)
+
+      # The service is also called when the merge params are updated.
+      already_approved = merge_request.merge_when_build_succeeds?
+
+      unless already_approved
+        merge_request.merge_when_build_succeeds = true
+        merge_request.merge_user                = @current_user
+
+        SystemNoteService.merge_when_build_succeeds(merge_request, @project, @current_user, merge_request.last_commit)
+      end
+
+      merge_request.save
+    end
+
+    # Triggers the automatic merge of merge_request once the build succeeds
+    def trigger(build)
+      merge_requests = merge_request_from(build)
+
+      merge_requests.each do |merge_request|
+        next unless merge_request.merge_when_build_succeeds?
+
+        if merge_request.ci_commit && merge_request.ci_commit.success? && merge_request.mergeable?
+          MergeWorker.perform_async(merge_request.id, merge_request.merge_user_id, merge_request.merge_params)
+        end
+      end
+    end
+
+    # Cancels the automatic merge
+    def cancel(merge_request)
+      if merge_request.merge_when_build_succeeds? && merge_request.open?
+        merge_request.reset_merge_when_build_succeeds
+        SystemNoteService.cancel_merge_when_build_succeeds(merge_request, @project, @current_user)
+
+        success
+      else
+        error("Can't cancel the automatic merge", 406)
+      end
+    end
+
+    private
+
+    def merge_request_from(build)
+      merge_requests = @project.origin_merge_requests.opened.where(source_branch: build.ref).to_a
+      merge_requests += @project.fork_merge_requests.opened.where(source_branch: build.ref).to_a
+
+      merge_requests.uniq.select(&:source_project)
+    end
+  end
+end

app/services/merge_requests/refresh_service.rb

@@ -11,6 +11,7 @@ module MergeRequests
       # empty diff during a manual merge
       close_merge_requests
       reload_merge_requests
+      reset_merge_when_build_succeeds
 
       # Leave a system note if a branch was deleted/added
       if branch_added? || branch_removed?
@@ -57,7 +58,6 @@ module MergeRequests
       merge_requests = filter_merge_requests(merge_requests)
 
       merge_requests.each do |merge_request|
-
         if merge_request.source_branch == @branch_name || force_push?
           merge_request.reload_code
           merge_request.mark_as_unchecked
@@ -76,6 +76,10 @@ module MergeRequests
       end
     end
 
+    def reset_merge_when_build_succeeds
+      merge_requests_for_source_branch.each(&:reset_merge_when_build_succeeds)
+    end
+
     def find_new_commits
       if branch_added?
         @commits = []

app/services/system_note_service.rb

@@ -130,6 +130,20 @@ class SystemNoteService
     create_note(noteable: noteable, project: project, author: author, note: body)
   end
 
+  # Called when 'merge when build succeeds' is executed
+  def self.merge_when_build_succeeds(noteable, project, author, last_commit)
+    body = "Enabled an automatic merge when the build for #{last_commit.to_reference(project)} succeeds"
+
+    create_note(noteable: noteable, project: project, author: author, note: body)
+  end
+
+  # Called when 'merge when build succeeds' is canceled
+  def self.cancel_merge_when_build_succeeds(noteable, project, author)
+    body = "Canceled the automatic merge"
+
+    create_note(noteable: noteable, project: project, author: author, note: body)
+  end
+
   # Called when the title of a Noteable is changed
   #
   # noteable  - Noteable object that responds to `title`

app/views/projects/merge_requests/_merge_request.html.haml

@@ -1,11 +1,10 @@
-- ci_commit = merge_request.ci_commit
 %li{ class: mr_css_classes(merge_request) }
   .merge-request-title
     %span.merge-request-title-text
       = link_to_gfm merge_request.title, merge_request_path(merge_request), class: "row_title"
     .pull-right.light
-      - if ci_commit
-        = render_ci_status(ci_commit)
+      - if merge_request.ci_commit
+        = render_ci_status(merge_request.ci_commit)
       - if merge_request.merged?
         %span
           = icon('check')

app/views/projects/merge_requests/cancel_merge_when_build_succeeds.js.haml

@@ -0,0 +1,2 @@
+:plain
+  $('.mr-widget-body').html("#{escape_javascript(render('projects/merge_requests/widget/open/accept'))}");

app/views/projects/merge_requests/merge.js.haml

@@ -1,6 +1,10 @@
-- if @status
+- case @status
+- when :success
   :plain
     merge_request_widget.mergeInProgress(#{params[:should_remove_source_branch] == '1'});
+- when :merge_when_build_succeeds
+  :plain
+    $('.mr-widget-body').html("#{escape_javascript(render('projects/merge_requests/widget/open/merge_when_build_succeeds'))}");
 - else
   :plain
     $('.mr-widget-body').html("#{escape_javascript(render('projects/merge_requests/widget/open/reload'))}");

app/views/projects/merge_requests/widget/_merged.html.haml

@@ -14,7 +14,7 @@
             = @merge_request.target_branch
         The source branch has been removed.
 
-      - elsif can_remove_branch?(@merge_request.source_project, @merge_request.source_branch)
+      - elsif @merge_request.can_remove_source_branch?(current_user)
         .remove_source_branch_widget
           %p
             = succeed '.' do
@@ -50,5 +50,3 @@
             $('.remove_source_branch_in_progress').hide();
             $('.remove_source_branch_widget.failed').show();
           });
-
-

app/views/projects/merge_requests/widget/_open.html.haml

@@ -13,6 +13,8 @@
       = render 'projects/merge_requests/widget/open/conflicts'
     - elsif @merge_request.work_in_progress?
       = render 'projects/merge_requests/widget/open/wip'
+    - elsif @merge_request.merge_when_build_succeeds?
+      = render 'projects/merge_requests/widget/open/merge_when_build_succeeds'
     - elsif !@merge_request.can_be_merged_by?(current_user)
       = render 'projects/merge_requests/widget/open/not_allowed'
     - elsif @merge_request.can_be_merged?

app/views/projects/merge_requests/widget/open/_accept.html.haml

@@ -3,26 +3,60 @@
 = form_for [:merge, @project.namespace.becomes(Namespace), @project, @merge_request], remote: true, method: :post, html: { class: 'accept-mr-form js-requires-input' } do |f|
   = hidden_field_tag :authenticity_token, form_authenticity_token
   .accept-merge-holder.clearfix.js-toggle-container
-    .accept-action
-      = f.button class: "btn btn-create accept_merge_request#{status_class}" do
-        Accept Merge Request
-    - if can_remove_branch?(@merge_request.source_project, @merge_request.source_branch) && !@merge_request.for_fork?
-      .accept-control.checkbox
-        = label_tag :should_remove_source_branch, class: "remove_source_checkbox" do
-          = check_box_tag :should_remove_source_branch
-          Remove source branch
-    .accept-control.right
-      = link_to "#", class: "modify-merge-commit-link js-toggle-button" do
-        = icon('edit')
-        Modify commit message
-    .js-toggle-content.hide.prepend-top-20
+    .clearfix
+      .accept-action
+        - if @ci_commit && @ci_commit.active?
+          %span.btn-group
+            = link_to "#", class: "btn btn-create merge_when_build_succeeds" do
+              Merge When Build Succeeds
+            %a.btn.btn-success.dropdown-toggle{ 'data-toggle' => 'dropdown' }
+              %span.caret
+              %span.sr-only
+                Select Merge Moment
+            %ul.dropdown-menu.dropdown-menu-right{ role: 'menu' }
+              %li
+                = link_to "#", class: "merge_when_build_succeeds" do
+                  = icon('check fw')
+                  Merge When Build Succeeds
+              %li
+                = link_to "#", class: "accept_merge_request" do
+                  = icon('warning fw')
+                  Merge Immediately
+        - else
+          = f.button class: "btn btn-create btn-grouped accept_merge_request #{status_class}" do
+            Accept Merge Request
+      - if @merge_request.can_remove_source_branch?(current_user)
+        .accept-control.checkbox
+          = label_tag :should_remove_source_branch, class: "remove_source_checkbox" do
+            = check_box_tag :should_remove_source_branch
+            Remove source branch
+      .accept-control.right
+        = link_to "#", class: "modify-merge-commit-link js-toggle-button" do
+          = icon('edit')
+          Modify commit message
+    .js-toggle-content.hide.prepend-top-default
       = render 'shared/commit_message_container', params: params,
           text: @merge_request.merge_commit_message,
           rows: 14, hint: true
 
+    = hidden_field_tag :merge_when_build_succeeds, "", autocomplete: "off"
+
   :javascript
-    $('.accept-mr-form').on('ajax:before', function() {
-      var btn = $('.accept_merge_request');
-      btn.disable();
-      btn.html("<i class='fa fa-spinner fa-spin'></i> Merge in progress");
+    $('.accept_merge_request').on('click', function() {
+      $(this).html("<i class='fa fa-spinner fa-spin'></i> Merge in progress");
+    });
+
+    $('.accept-mr-form').on('ajax:send', function() {
+      $(".accept-mr-form :input").disable();
+    });
+
+    $('a.accept_merge_request').on('click', function(e) {
+      e.preventDefault();
+      $(this).closest("form").submit();
+    });
+
+    $('a.merge_when_build_succeeds').on('click', function(e) {
+      e.preventDefault();
+      $("#merge_when_build_succeeds").val("1");
+      $(this).closest("form").submit();
     });

app/views/projects/merge_requests/widget/open/_merge_when_build_succeeds.html.haml

@@ -0,0 +1,26 @@
+%h4
+  Set by #{link_to_member(@project, @merge_request.merge_user, avatar: true)}
+  to be merged automatically when the build succeeds.
+%div
+  - should_remove_source_branch = @merge_request.merge_params["should_remove_source_branch"].present?
+  %p
+    = succeed '.' do
+      The changes will be merged into
+      %span.label-branch= @merge_request.target_branch
+    - if should_remove_source_branch
+      The source branch will be removed.
+    - else
+      The source branch will not be removed.
+
+  - remove_source_branch_button = @merge_request.can_remove_source_branch?(current_user) && !should_remove_source_branch
+  - user_can_cancel_automatic_merge = @merge_request.can_cancel_merge_when_build_succeeds?(current_user)
+  - if remove_source_branch_button || user_can_cancel_automatic_merge
+    .clearfix.prepend-top-10
+      - if remove_source_branch_button
+        = link_to merge_namespace_project_merge_request_path(@merge_request.target_project.namespace, @merge_request.target_project, @merge_request, merge_when_build_succeeds: true, should_remove_source_branch: true), remote: true, method: :post, class: "btn btn-grouped btn-primary btn-sm remove_source_branch" do
+          = icon('times')
+          Remove Source Branch When Merged
+
+      - if user_can_cancel_automatic_merge
+        = link_to cancel_merge_when_build_succeeds_namespace_project_merge_request_path(@merge_request.target_project.namespace, @merge_request.target_project, @merge_request), remote: true, method: :post, class: "btn btn-grouped btn-warning btn-sm" do
+          Cancel Automatic Merge

app/workers/merge_worker.rb

@@ -8,16 +8,7 @@ class MergeWorker
     current_user = User.find(current_user_id)
     merge_request = MergeRequest.find(merge_request_id)
 
-    result = MergeRequests::MergeService.new(merge_request.target_project, current_user).
-      execute(merge_request, params[:commit_message])
-
-    if result[:status] == :success && params[:should_remove_source_branch].present?
-      DeleteBranchService.new(merge_request.source_project, current_user).
-        execute(merge_request.source_branch)
-
-      merge_request.source_project.repository.expire_branch_names
-    end
-
-    result
+    MergeRequests::MergeService.new(merge_request.target_project, current_user, params).
+      execute(merge_request)
   end
 end

config/routes.rb

@@ -573,8 +573,9 @@ Rails.application.routes.draw do
             get :commits
             get :diffs
             get :builds
-            post :merge
             get :merge_check
+            post :merge
+            post :cancel_merge_when_build_succeeds
             get :ci_status
             post :toggle_subscription
           end

db/migrate/20151028152939_add_merge_when_build_succeeds_to_merge_request.rb

@@ -0,0 +1,7 @@
+class AddMergeWhenBuildSucceedsToMergeRequest < ActiveRecord::Migration
+  def change
+    add_column :merge_requests, :merge_params, :text
+    add_column :merge_requests, :merge_when_build_succeeds, :boolean, default: false, null: false
+    add_column :merge_requests, :merge_user_id, :integer
+  end
+end

db/schema.rb

@@ -476,9 +476,9 @@ ActiveRecord::Schema.define(version: 20151203162133) do
   add_index "merge_request_diffs", ["merge_request_id"], name: "index_merge_request_diffs_on_merge_request_id", unique: true, using: :btree
 
   create_table "merge_requests", force: :cascade do |t|
-    t.string   "target_branch",                 null: false
-    t.string   "source_branch",                 null: false
-    t.integer  "source_project_id",             null: false
+    t.string   "target_branch",                             null: false
+    t.string   "source_branch",                             null: false
+    t.integer  "source_project_id",                         null: false
     t.integer  "author_id"
     t.integer  "assignee_id"
     t.string   "title"
@@ -487,13 +487,16 @@ ActiveRecord::Schema.define(version: 20151203162133) do
     t.integer  "milestone_id"
     t.string   "state"
     t.string   "merge_status"
-    t.integer  "target_project_id",             null: false
+    t.integer  "target_project_id",                         null: false
     t.integer  "iid"
     t.text     "description"
-    t.integer  "position",          default: 0
+    t.integer  "position",                  default: 0
     t.datetime "locked_at"
     t.integer  "updated_by_id"
     t.string   "merge_error"
+    t.text     "merge_params"
+    t.boolean  "merge_when_build_succeeds", default: false, null: false
+    t.integer  "merge_user_id"
   end
 
   add_index "merge_requests", ["assignee_id"], name: "index_merge_requests_on_assignee_id", using: :btree

doc/api/merge_requests.md

@@ -335,9 +335,57 @@ PUT /projects/:id/merge_request/:merge_request_id/merge
 
 Parameters:
 
-- `id` (required)                   - The ID of a project
-- `merge_request_id` (required)     - ID of MR
-- `merge_commit_message` (optional) - Custom merge commit message
+- `id` (required)                           - The ID of a project
+- `merge_request_id` (required)             - ID of MR
+- `merge_commit_message` (optional)         - Custom merge commit message
+- `should_remove_source_branch` (optional)  - if `true` removes the source branch
+- `merged_when_build_succeeds` (optional)    - if `true` the MR is merge when the build succeeds
+
+```json
+{
+  "id": 1,
+  "target_branch": "master",
+  "source_branch": "test1",
+  "project_id": 3,
+  "title": "test1",
+  "state": "merged",
+  "upvotes": 0,
+  "downvotes": 0,
+  "author": {
+    "id": 1,
+    "username": "admin",
+    "email": "admin@example.com",
+    "name": "Administrator",
+    "state": "active",
+    "created_at": "2012-04-29T08:46:00Z"
+  },
+  "assignee": {
+    "id": 1,
+    "username": "admin",
+    "email": "admin@example.com",
+    "name": "Administrator",
+    "state": "active",
+    "created_at": "2012-04-29T08:46:00Z"
+  }
+}
+```
+
+## Cancel Merge When Build Succeeds
+
+If successful you'll get `200 OK`.
+
+If you don't have permissions to accept this merge request - you'll get a 401
+
+If the merge request is already merged or closed - you get 405 and error message 'Method Not Allowed'
+
+In case the merge request is not set to be merged when the build succeeds, you'll also get a 406 error.
+```
+PUT /projects/:id/merge_request/:merge_request_id/cancel_merge_when_build_succeeds
+```
+Parameters:
+
+- `id` (required)                           - The ID of a project
+- `merge_request_id` (required)             - ID of MR
 
 ```json
 {

doc/workflow/README.md

@@ -17,4 +17,5 @@
 - [Milestones](milestones.md)
 - [Merge Requests](merge_requests.md)
 - ["Work In Progress" Merge Requests](wip_merge_requests.md)
+- [Merge When Build Succeeds](merge_when_build_succeeds.md)
 - [Manage large binaries with Git LFS](lfs/manage_large_binaries_with_git_lfs.md)

doc/workflow/merge_when_build_succeeds.md

@@ -0,0 +1,15 @@
+# Merge When Build Succeeds
+
+When reviewing a merge request that looks ready to merge but still has one or more CI builds running, you can set it to be merged automatically when all builds succeed. This way, you don't have to wait for the builds to finish and remember to merge the request manually.
+
+![Enable](merge_when_build_succeeds/enable.png)
+
+When you hit the "Merge When Build Succeeds" button, the status of the merge request will be updated to represent the impending merge. If you cannot wait for the build to succeed and want to merge immediately, this option is available in the dropdown menu on the right of the main button.
+
+Both team developers and the author of the merge request have the option to cancel the automatic merge if they find a reason why it shouldn't be merged after all.
+
+![Status](merge_when_build_succeeds/status.png)
+
+When the build succeeds, the merge request will automatically be merged. When the build fails, the author gets a chance to retry any failed builds, or to push new commits to fix the failure.
+
+When the builds are retried and succeed on the second try, the merge request will automatically be merged after all. When the merge request is updated with new commits, the automatic merge is automatically canceled to allow the new changes to be reviewed.

lib/api/entities.rb

@@ -171,6 +171,7 @@ module API
       expose :description
       expose :work_in_progress?, as: :work_in_progress
       expose :milestone, using: Entities::Milestone
+      expose :merge_when_build_succeeds
     end
 
     class MergeRequestChanges < MergeRequest

lib/api/merge_requests.rb

@@ -195,46 +195,54 @@ module API
       # Merge MR
       #
       # Parameters:
-      #   id (required)                   - The ID of a project
-      #   merge_request_id (required)     - ID of MR
-      #   merge_commit_message (optional) - Custom merge commit message
+      #   id (required)                           - The ID of a project
+      #   merge_request_id (required)             - ID of MR
+      #   merge_commit_message (optional)         - Custom merge commit message
+      #   should_remove_source_branch (optional)  - When true, the source branch will be deleted if possible
+      #   merge_when_build_succeeds (optional)    - When true, this MR will be merged when the build succeeds
       # Example:
       #   PUT /projects/:id/merge_request/:merge_request_id/merge
       #
       put ":id/merge_request/:merge_request_id/merge" do
         merge_request = user_project.merge_requests.find(params[:merge_request_id])
 
-        allowed = ::Gitlab::GitAccess.new(current_user, user_project).
-          can_push_to_branch?(merge_request.target_branch)
+        # Merge request can not be merged
+        # because user dont have permissions to push into target branch
+        unauthorized! unless merge_request.can_be_merged_by?(current_user)
+        not_allowed! if !merge_request.open? || merge_request.work_in_progress?
 
-        if allowed
-          if merge_request.unchecked?
-            merge_request.check_if_can_be_merged
-          end
+        merge_request.check_if_can_be_merged if merge_request.unchecked?
 
-          if merge_request.open? && !merge_request.work_in_progress?
-            if merge_request.can_be_merged?
-              commit_message = params[:merge_commit_message] || merge_request.merge_commit_message
+        render_api_error!('Branch cannot be merged', 406) unless merge_request.can_be_merged?
 
-              ::MergeRequests::MergeService.new(merge_request.target_project, current_user).
-                execute(merge_request, commit_message)
+        merge_params = {
+          commit_message: params[:merge_commit_message],
+          should_remove_source_branch: params[:should_remove_source_branch]
+        }
 
-              present merge_request, with: Entities::MergeRequest
-            else
-              render_api_error!('Branch cannot be merged', 405)
-            end
-          else
-            # Merge request can not be merged
-            # because it is already closed/merged or marked as WIP
-            not_allowed!
-          end
+        if parse_boolean(params[:merge_when_build_succeeds]) && merge_request.ci_commit && merge_request.ci_commit.active?
+          ::MergeRequests::MergeWhenBuildSucceedsService.new(merge_request.target_project, current_user, merge_params).
+            execute(merge_request)
         else
-          # Merge request can not be merged
-          # because user dont have permissions to push into target branch
-          unauthorized!
+          ::MergeRequests::MergeService.new(merge_request.target_project, current_user, merge_params).
+            execute(merge_request)
         end
+
+        present merge_request, with: Entities::MergeRequest
       end
 
+      # Cancel Merge if Merge When build succeeds is enabled
+      # Parameters:
+      #   id (required)                         - The ID of a project
+      #   merge_request_id (required)           - ID of MR
+      #
+      post ":id/merge_request/:merge_request_id/cancel_merge_when_build_succeeds" do
+        merge_request = user_project.merge_requests.find(params[:merge_request_id])
+
+        unauthorized! unless merge_request.can_cancel_merge_when_build_succeeds?(current_user)
+
+        ::MergeRequest::MergeWhenBuildSucceedsService.new(merge_request.target_project, current_user).cancel(merge_request)
+      end
 
       # Get a merge request's comments
       #

spec/factories/ci/commits.rb

@@ -2,17 +2,18 @@
 #
 # Table name: commits
 #
-#  id           :integer          not null, primary key
-#  project_id   :integer
-#  ref          :string(255)
-#  sha          :string(255)
-#  before_sha   :string(255)
-#  push_data    :text
-#  created_at   :datetime
-#  updated_at   :datetime
-#  tag          :boolean          default(FALSE)
-#  yaml_errors  :text
-#  committed_at :datetime
+#  id             :integer          not null, primary key
+#  project_id     :integer
+#  ref            :string(255)
+#  sha            :string(255)
+#  before_sha     :string(255)
+#  push_data      :text
+#  created_at     :datetime
+#  updated_at     :datetime
+#  tag            :boolean          default(FALSE)
+#  yaml_errors    :text
+#  committed_at   :datetime
+#  gl_project_id  :integer
 #
 
 # Read about factories at https://github.com/thoughtbot/factory_girl

spec/factories/commit_statuses.rb

@@ -5,7 +5,7 @@ FactoryGirl.define do
     name 'default'
     status 'success'
     description 'commit status'
-    commit factory: :ci_commit
+    commit factory: :ci_commit_with_one_job
 
     factory :generic_commit_status, class: GenericCommitStatus do
       name 'generic'

spec/factories/merge_requests.rb

@@ -65,6 +65,11 @@ FactoryGirl.define do
       target_branch "master"
     end
 
+    trait :merge_when_build_succeeds do
+      merge_when_build_succeeds true
+      merge_user author
+    end
+
     factory :closed_merge_request, traits: [:closed]
     factory :reopened_merge_request, traits: [:reopened]
     factory :merge_request_with_diffs, traits: [:with_diffs]

spec/features/merge_requests/merge_when_build_succeeds_spec.rb

@@ -0,0 +1,85 @@
+require 'spec_helper'
+
+feature 'Merge When Build Succeeds', feature: true, js: true do
+  let(:user) { create(:user) }
+
+  let(:project)       { create(:project, :public) }
+  let(:merge_request) { create(:merge_request_with_diffs, source_project: project, author: user, title: "Bug NS-04") }
+
+  before do
+    project.team << [user, :master]
+    project.enable_ci
+  end
+
+  context "Active build for Merge Request" do
+    let!(:ci_commit) { create(:ci_commit, gl_project: project, sha: merge_request.last_commit.id, ref: merge_request.source_branch) }
+    let!(:ci_build) { create(:ci_build, commit: ci_commit) }
+
+    before do
+      login_as user
+      visit_merge_request(merge_request)
+    end
+
+    it 'displays the Merge When Build Succeeds button' do
+      expect(page).to have_link "Merge When Build Succeeds"
+    end
+
+    context "Merge When Build succeeds enabled" do
+      before do
+        click_link "Merge When Build Succeeds"
+      end
+
+      it 'activates Merge When Build Succeeds feature' do
+        expect(page).to have_link "Cancel Automatic Merge"
+
+        expect(page).to have_content "Set by #{user.name} to be merged automatically when the build succeeds."
+        expect(page).to have_content "The source branch will not be removed."
+
+        visit_merge_request(merge_request) # Needed to refresh the page
+        expect(page).to have_content /Enabled an automatic merge when the build for [0-9a-f]{8} succeeds/i
+      end
+    end
+  end
+
+  context 'When it is enabled' do
+    let(:merge_request) do
+      create(:merge_request_with_diffs, :simple,  source_project: project, author: user,
+                                                  merge_user: user, title: "MepMep", merge_when_build_succeeds: true)
+    end
+
+    let!(:ci_commit) { create(:ci_commit, gl_project: project, sha: merge_request.last_commit.id, ref: merge_request.source_branch) }
+    let!(:ci_build) { create(:ci_build, commit: ci_commit) }
+
+    before do
+      login_as user
+      visit_merge_request(merge_request)
+    end
+
+    it 'cancels the automatic merge' do
+      click_link "Cancel Automatic Merge"
+
+      expect(page).to have_link  "Merge When Build Succeeds"
+
+      visit_merge_request(merge_request) # Needed to refresh the page
+      expect(page).to have_content "Canceled the automatic merge"
+    end
+
+    it "allows the user to remove the source branch" do
+      expect(page).to have_link "Remove Source Branch When Merged"
+
+      click_link "Remove Source Branch When Merged"
+      expect(page).to have_content "The source branch will be removed"
+    end
+  end
+
+  context 'Build is not active' do
+    it "should not allow for enabling" do
+      visit_merge_request(merge_request)
+      expect(page).not_to have_link "Merge When Build Succeeds"
+    end
+  end
+
+  def visit_merge_request(merge_request)
+    visit namespace_project_merge_request_path(merge_request.project.namespace, merge_request.project, merge_request)
+  end
+end

spec/models/merge_request_spec.rb

@@ -31,7 +31,7 @@ describe MergeRequest do
   describe 'associations' do
     it { is_expected.to belong_to(:target_project).with_foreign_key(:target_project_id).class_name('Project') }
     it { is_expected.to belong_to(:source_project).with_foreign_key(:source_project_id).class_name('Project') }
-
+    it { is_expected.to belong_to(:merge_user).class_name("User") }
     it { is_expected.to have_one(:merge_request_diff).dependent(:destroy) }
   end
 
@@ -48,12 +48,32 @@ describe MergeRequest do
   describe 'validation' do
     it { is_expected.to validate_presence_of(:target_branch) }
     it { is_expected.to validate_presence_of(:source_branch) }
+
+    context "Validation of merge user with Merge When Build succeeds" do
+      it "allows user to be nil when the feature is disabled" do
+        expect(subject).to be_valid
+      end
+
+      it "is invalid without merge user" do
+        subject.merge_when_build_succeeds = true
+        expect(subject).not_to be_valid
+      end
+
+      it "is valid with merge user" do
+        subject.merge_when_build_succeeds = true
+        subject.merge_user = build(:user)
+
+        expect(subject).to be_valid
+      end
+    end
   end
 
   describe 'respond to' do
     it { is_expected.to respond_to(:unchecked?) }
     it { is_expected.to respond_to(:can_be_merged?) }
     it { is_expected.to respond_to(:cannot_be_merged?) }
+    it { is_expected.to respond_to(:merge_params) }
+    it { is_expected.to respond_to(:merge_when_build_succeeds) }
   end
 
   describe '#to_reference' do
@@ -172,6 +192,50 @@ describe MergeRequest do
     end
   end
 
+  describe '#can_remove_source_branch?' do
+    let(:user) { create(:user) }
+    let(:user2) { create(:user) }
+
+    before do
+      subject.source_project.team << [user, :master]
+
+      subject.source_branch = "feature"
+      subject.target_branch = "master"
+      subject.save!
+    end
+
+    it "can't be removed when its a protected branch" do
+      allow(subject.source_project).to receive(:protected_branch?).and_return(true)
+      expect(subject.can_remove_source_branch?(user)).to be_falsey
+    end
+
+    it "cant remove a root ref" do
+      subject.source_branch = "master"
+      subject.target_branch = "feature"
+
+      expect(subject.can_remove_source_branch?(user)).to be_falsey
+    end
+
+    it "is unable to remove the source branch for a project the user cannot push to" do
+      expect(subject.can_remove_source_branch?(user2)).to be_falsey
+    end
+
+    it "is can be removed in all other cases" do
+      expect(subject.can_remove_source_branch?(user)).to be_truthy
+    end
+  end
+
+  describe "#reset_merge_when_build_succeeds" do
+    let(:merge_if_green) { create :merge_request, merge_when_build_succeeds: true, merge_user: create(:user) }
+
+    it "sets the item to false" do
+      merge_if_green.reset_merge_when_build_succeeds
+      merge_if_green.reload
+
+      expect(merge_if_green.merge_when_build_succeeds).to be_falsey
+    end
+  end
+
   describe "#hook_attrs" do
     it "has all the required keys" do
       attrs = subject.hook_attrs

spec/requests/api/merge_requests_spec.rb

@@ -320,19 +320,21 @@ describe API::API, api: true  do
   end
 
   describe "PUT /projects/:id/merge_request/:merge_request_id/merge" do
+    let(:ci_commit) { create(:ci_commit_without_jobs) }
+
     it "should return merge_request in case of success" do
       put api("/projects/#{project.id}/merge_request/#{merge_request.id}/merge", user)
 
       expect(response.status).to eq(200)
     end
 
-    it "should return 405 if branch can't be merged" do
+    it "should return 406 if branch can't be merged" do
       allow_any_instance_of(MergeRequest).
         to receive(:can_be_merged?).and_return(false)
 
       put api("/projects/#{project.id}/merge_request/#{merge_request.id}/merge", user)
 
-      expect(response.status).to eq(405)
+      expect(response.status).to eq(406)
       expect(json_response['message']).to eq('Branch cannot be merged')
     end
 
@@ -357,6 +359,17 @@ describe API::API, api: true  do
       expect(response.status).to eq(401)
       expect(json_response['message']).to eq('401 Unauthorized')
     end
+
+    it "enables merge when build succeeds if the ci is active" do
+      allow_any_instance_of(MergeRequest).to receive(:ci_commit).and_return(ci_commit)
+      allow(ci_commit).to receive(:active?).and_return(true)
+
+      put api("/projects/#{project.id}/merge_request/#{merge_request.id}/merge", user), merge_when_build_succeeds: true
+
+      expect(response.status).to eq(200)
+      expect(json_response['title']).to eq('Test')
+      expect(json_response['merge_when_build_succeeds']).to eq(true)
+    end
   end
 
   describe "PUT /projects/:id/merge_request/:merge_request_id" do

spec/services/merge_requests/merge_service_spec.rb

@@ -13,12 +13,13 @@ describe MergeRequests::MergeService do
 
   describe :execute do
     context 'valid params' do
-      let(:service) { MergeRequests::MergeService.new(project, user, {}) }
+      let(:service) { MergeRequests::MergeService.new(project, user, commit_message: 'Awesome message') }
 
       before do
         allow(service).to receive(:execute_hooks)
+
         perform_enqueued_jobs do
-          service.execute(merge_request, 'Awesome message')
+          service.execute(merge_request)
         end
       end
 
@@ -38,14 +39,14 @@ describe MergeRequests::MergeService do
     end
 
     context "error handling" do
-      let(:service) { MergeRequests::MergeService.new(project, user, {}) }
+      let(:service) { MergeRequests::MergeService.new(project, user, commit_message: 'Awesome message') }
 
       it 'saves error if there is an exception' do
         allow(service).to receive(:repository).and_raise("error")
 
         allow(service).to receive(:execute_hooks)
 
-        service.execute(merge_request, 'Awesome message')
+        service.execute(merge_request)
 
         expect(merge_request.merge_error).to eq("Something went wrong during merge")
       end

spec/services/merge_requests/merge_when_build_succeeds_service_spec.rb

@@ -0,0 +1,84 @@
+require 'spec_helper'
+
+describe MergeRequests::MergeWhenBuildSucceedsService do
+  let(:user)          { create(:user) }
+  let(:merge_request) { create(:merge_request) }
+
+  let(:mr_merge_if_green_enabled) do
+    create(:merge_request, merge_when_build_succeeds: true, merge_user: user,
+                           source_branch: "source_branch", target_branch: project.default_branch,
+                           source_project: project, target_project: project, state: "opened")
+  end
+
+  let(:project) { create(:project) }
+  let(:ci_commit) { create(:ci_commit_with_one_job, ref: mr_merge_if_green_enabled.source_branch, gl_project: project) }
+  let(:service) { MergeRequests::MergeWhenBuildSucceedsService.new(project, user, commit_message: 'Awesome message') }
+
+  describe "#execute" do
+    context 'first time enabling' do
+      before do
+        allow(merge_request).to receive(:ci_commit).and_return(ci_commit)
+        service.execute(merge_request)
+      end
+
+      it 'sets the params, merge_user, and flag' do
+        expect(merge_request).to be_valid
+        expect(merge_request.merge_when_build_succeeds).to be_truthy
+        expect(merge_request.merge_params).to eq commit_message: 'Awesome message'
+        expect(merge_request.merge_user).to be user
+      end
+
+      it 'creates a system note' do
+        note = merge_request.notes.last
+        expect(note.note).to match /Enabled an automatic merge when the build for (\w+\/\w+@)?[0-9a-z]{8}/
+      end
+    end
+
+    context 'already approved' do
+      let(:service) { MergeRequests::MergeWhenBuildSucceedsService.new(project, user, new_key: true) }
+      let(:build)   { create(:ci_build, ref: mr_merge_if_green_enabled.source_branch) }
+
+      before do
+        allow(mr_merge_if_green_enabled).to receive(:ci_commit).and_return(ci_commit)
+        allow(mr_merge_if_green_enabled).to receive(:mergeable?).and_return(true)
+        allow(ci_commit).to receive(:success?).and_return(true)
+      end
+
+      it 'updates the merge params' do
+        expect(SystemNoteService).not_to receive(:merge_when_build_succeeds)
+
+        service.execute(mr_merge_if_green_enabled)
+        expect(mr_merge_if_green_enabled.merge_params).to have_key(:new_key)
+      end
+    end
+  end
+
+  describe "#trigger" do
+    let(:build)     { create(:ci_build, ref: mr_merge_if_green_enabled.source_branch, status: "success") }
+
+    it "merges all merge requests with merge when build succeeds enabled" do
+      allow_any_instance_of(MergeRequest).to receive(:ci_commit).and_return(ci_commit)
+      allow(ci_commit).to receive(:success?).and_return(true)
+
+      expect(MergeWorker).to receive(:perform_async)
+      service.trigger(build)
+    end
+  end
+
+  describe "#cancel" do
+    before do
+      service.cancel(mr_merge_if_green_enabled)
+    end
+
+    it "resets all the merge_when_build_succeeds params" do
+      expect(mr_merge_if_green_enabled.merge_when_build_succeeds).to be_falsey
+      expect(mr_merge_if_green_enabled.merge_params).to eq({})
+      expect(mr_merge_if_green_enabled.merge_user).to be nil
+    end
+
+    it 'Posts a system note' do
+      note = mr_merge_if_green_enabled.notes.last
+      expect(note.note).to include 'Canceled the automatic merge'
+    end
+  end
+end

spec/services/merge_requests/refresh_service_spec.rb

@@ -17,7 +17,9 @@ describe MergeRequests::RefreshService do
                               source_project: @project,
                               source_branch: 'master',
                               target_branch: 'feature',
-                              target_project: @project)
+                              target_project: @project,
+                              merge_when_build_succeeds: true,
+                              merge_user: @user)
 
       @fork_merge_request = create(:merge_request,
                                    source_project: @fork_project,
@@ -46,6 +48,7 @@ describe MergeRequests::RefreshService do
 
       it { expect(@merge_request.notes).not_to be_empty }
       it { expect(@merge_request).to be_open }
+      it { expect(@merge_request.merge_when_build_succeeds).to be_falsey}
       it { expect(@fork_merge_request).to be_open }
       it { expect(@fork_merge_request.notes).to be_empty }
     end
@@ -146,6 +149,7 @@ describe MergeRequests::RefreshService do
       end
     end
 
+
     def reload_mrs
       @merge_request.reload
       @fork_merge_request.reload

spec/services/system_note_service_spec.rb

@@ -207,6 +207,32 @@ describe SystemNoteService do
     end
   end
 
+  describe '.merge_when_build_succeeds' do
+    let(:ci_commit) { build :ci_commit_without_jobs }
+    let(:noteable) { create :merge_request }
+
+    subject { described_class.merge_when_build_succeeds(noteable, project, author, noteable.last_commit) }
+
+    it_behaves_like 'a system note'
+
+    it "posts the Merge When Build Succeeds system note" do
+      expect(subject.note).to match  /Enabled an automatic merge when the build for (\w+\/\w+@)?[0-9a-f]{40} succeeds/
+    end
+  end
+
+  describe '.cancel_merge_when_build_succeeds' do
+    let(:ci_commit) { build :ci_commit_without_jobs }
+    let(:noteable) { create :merge_request }
+
+    subject { described_class.cancel_merge_when_build_succeeds(noteable, project, author) }
+
+    it_behaves_like 'a system note'
+
+    it "posts the Merge When Build Succeeds system note" do
+      expect(subject.note).to eq  "Canceled the automatic merge"
+    end
+  end
+
   describe '.change_title' do
     subject { described_class.change_title(noteable, project, author, 'Old title') }