Replaces "Create merge request" link with one to the MR when one exists

8 files changed, 122 insertions, 9 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 800f9c7918f..94873b4e35c 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -51,6 +51,7 @@ v 8.4.4
   - Update omniauth-saml gem to 1.4.2
   - Prevent long-running backup tasks from timing out the database connection
   - Add a Project setting to allow guests to view build logs (defaults to true)
+  - Replaces "Create merge request" link with one to the "Merge Request" when one exists
 
 v 8.4.3
   - Increase lfs_objects size column to 8-byte integer to allow files larger
diff --git a/app/controllers/projects/commits_controller.rb b/app/controllers/projects/commits_controller.rb
index bf5b54c8cb7..1420b96840c 100644
--- a/app/controllers/projects/commits_controller.rb
+++ b/app/controllers/projects/commits_controller.rb
@@ -21,6 +21,9 @@ class Projects::CommitsController < Projects::ApplicationController
     @note_counts = project.notes.where(commit_id: @commits.map(&:id)).
       group(:commit_id).count
 
+    @merge_request = @project.merge_requests.opened.
+      find_by(source_project: @project, source_branch: @ref, target_branch: @repository.root_ref)
+
     respond_to do |format|
       format.html
       format.json { pager_json("projects/commits/_commits", @commits.size) }
diff --git a/app/controllers/projects/compare_controller.rb b/app/controllers/projects/compare_controller.rb
index 7bbe75b3974..dc5d217f3e4 100644
--- a/app/controllers/projects/compare_controller.rb
+++ b/app/controllers/projects/compare_controller.rb
@@ -4,24 +4,23 @@ class Projects::CompareController < Projects::ApplicationController
   # Authorize
   before_action :require_non_empty_project
   before_action :authorize_download_code!
+  before_action :assign_ref_vars, only: [:index, :show]
+  before_action :merge_request, only: [:index, :show]
 
   def index
-    @ref = Addressable::URI.unescape(params[:to])
   end
 
   def show
-    base_ref = Addressable::URI.unescape(params[:from])
-    @ref = head_ref = Addressable::URI.unescape(params[:to])
     diff_options = { ignore_whitespace_change: true } if params[:w] == '1'
 
     compare_result = CompareService.new.
-      execute(@project, head_ref, @project, base_ref, diff_options)
+      execute(@project, @head_ref, @project, @base_ref, diff_options)
 
     if compare_result
       @commits = Commit.decorate(compare_result.commits, @project)
       @diffs = compare_result.diffs
-      @commit = @project.commit(head_ref)
-      @base_commit = @project.merge_base_commit(base_ref, head_ref)
+      @commit = @project.commit(@head_ref)
+      @base_commit = @project.merge_base_commit(@base_ref, @head_ref)
       @diff_refs = [@base_commit, @commit]
       @line_notes = []
     end
@@ -31,4 +30,16 @@ class Projects::CompareController < Projects::ApplicationController
     redirect_to namespace_project_compare_path(@project.namespace, @project,
                                                params[:from], params[:to])
   end
+
+  private
+
+  def assign_ref_vars
+    @base_ref = Addressable::URI.unescape(params[:from])
+    @ref = @head_ref = Addressable::URI.unescape(params[:to])
+  end
+
+  def merge_request
+    @merge_request ||= @project.merge_requests.opened.
+      find_by(source_project: @project, source_branch: @head_ref, target_branch: @base_ref)
+  end
 end
diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index ddc476447ca..345b9a26d4e 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -137,6 +137,7 @@ class MergeRequest < ActiveRecord::Base
   scope :by_milestone, ->(milestone) { where(milestone_id: milestone) }
   scope :in_projects, ->(project_ids) { where("source_project_id in (:project_ids) OR target_project_id in (:project_ids)", project_ids: project_ids) }
   scope :of_projects, ->(ids) { where(target_project_id: ids) }
+  scope :opened, -> { with_state(:opened) }
   scope :merged, -> { with_state(:merged) }
   scope :closed, -> { with_state(:closed) }
   scope :closed_and_merged, -> { with_states(:closed, :merged) }
diff --git a/app/views/projects/commits/show.html.haml b/app/views/projects/commits/show.html.haml
index ede64d47ab3..89e091203a3 100644
--- a/app/views/projects/commits/show.html.haml
+++ b/app/views/projects/commits/show.html.haml
@@ -11,7 +11,10 @@
     = render 'shared/ref_switcher', destination: 'commits'
 
   .block-controls.hidden-xs.hidden-sm
-    - if create_mr_button?(@repository.root_ref, @ref)
+    - if @merge_request.present?
+      .control
+        = link_to "View #{@merge_request.to_reference}", namespace_project_merge_request_path(@project.namespace, @project, @merge_request), class: 'btn btn-success'
+    - elsif create_mr_button?(@repository.root_ref, @ref)
       .control
         = link_to create_mr_path(@repository.root_ref, @ref), class: 'btn btn-success' do
           = icon('plus')
diff --git a/app/views/projects/compare/_form.html.haml b/app/views/projects/compare/_form.html.haml
index efc25eda26b..bdaa39055ad 100644
--- a/app/views/projects/compare/_form.html.haml
+++ b/app/views/projects/compare/_form.html.haml
@@ -13,12 +13,13 @@
         = text_field_tag :to, params[:to], class: "form-control", required: true
     &nbsp;
     = button_tag "Compare", class: "btn btn-create commits-compare-btn"
-    - if create_mr_button?
+    - if @merge_request.present?
+      = link_to "View #{@merge_request.to_reference}", namespace_project_merge_request_path(@project.namespace, @project, @merge_request), class: 'prepend-left-10 btn'
+    - elsif create_mr_button?
       = link_to create_mr_path, class: 'prepend-left-10 btn' do
         = icon("plus")
         Create Merge Request
 
-
 :javascript
   var availableTags = #{@project.repository.ref_names.to_json};
 
diff --git a/features/project/commits/commits.feature b/features/project/commits/commits.feature
index 01c10721312..a95df038357 100644
--- a/features/project/commits/commits.feature
+++ b/features/project/commits/commits.feature
@@ -7,6 +7,26 @@ Feature: Project Commits
 
   Scenario: I browse commits list for master branch
     Then I see project commits
+    And I should not see button to create a new merge request
+    Then I click the "Compare" tab
+    And I should not see button to create a new merge request
+
+  Scenario: I browse commits list for feature branch without a merge request
+    Given I visit commits list page for feature branch
+    Then I see feature branch commits
+    And I see button to create a new merge request
+    Then I click the "Compare" tab
+    And I see button to create a new merge request
+
+  Scenario: I browse commits list for feature branch with an open merge request
+    Given project have an open merge request
+    And I visit commits list page for feature branch
+    Then I see feature branch commits
+    And I should not see button to create a new merge request
+    And I should see button to the merge request
+    Then I click the "Compare" tab
+    And I should not see button to create a new merge request
+    And I should see button to the merge request
 
   Scenario: I browse atom feed of commits list for master branch
     Given I click atom feed link
@@ -31,6 +51,22 @@ Feature: Project Commits
     Then I see inline diff button
 
   @javascript
+  Scenario: I compare branches without a merge request
+    Given I visit compare refs page
+    And I fill compare fields with branches
+    Then I see compared branches
+    And I see button to create a new merge request
+
+  @javascript
+  Scenario: I compare branches with an open merge request
+    Given project have an open merge request
+    And I visit compare refs page
+    And I fill compare fields with branches
+    Then I see compared branches
+    And I should not see button to create a new merge request
+    And I should see button to the merge request
+
+  @javascript
   Scenario: I compare refs
     Given I visit compare refs page
     And I fill compare fields with refs
diff --git a/features/steps/project/commits/commits.rb b/features/steps/project/commits/commits.rb
index daf6cdaaac8..23814c2ee25 100644
--- a/features/steps/project/commits/commits.rb
+++ b/features/steps/project/commits/commits.rb
@@ -33,6 +33,13 @@ class Spinach::Features::ProjectCommits < Spinach::FeatureSteps
     expect(page).to have_content "Showing #{sample_commit.files_changed_count} changed files"
   end
 
+  step 'I fill compare fields with branches' do
+    fill_in 'from', with: 'feature'
+    fill_in 'to',   with: 'master'
+
+    click_button 'Compare'
+  end
+
   step 'I fill compare fields with refs' do
     fill_in "from", with: sample_commit.parent_id
     fill_in "to",   with: sample_commit.id
@@ -56,6 +63,56 @@ class Spinach::Features::ProjectCommits < Spinach::FeatureSteps
     expect(page).to have_content "Showing 2 changed files"
   end
 
+  step 'I visit commits list page for feature branch' do
+    visit namespace_project_commits_path(@project.namespace, @project, 'feature', { limit: 5 })
+  end
+
+  step 'I see feature branch commits' do
+    commit = @project.repository.commit('0b4bc9a')
+    expect(page).to have_content(@project.name)
+    expect(page).to have_content(commit.message[0..12])
+    expect(page).to have_content(commit.short_id)
+  end
+
+  step 'project have an open merge request' do
+    create(:merge_request,
+           title: 'Feature',
+           source_project: @project,
+           source_branch: 'feature',
+           target_branch: 'master',
+           author: @project.users.first
+          )
+  end
+
+  step 'I click the "Compare" tab' do
+    click_link('Compare')
+  end
+
+  step 'I fill compare fields with branches' do
+    fill_in 'from', with: 'master'
+    fill_in 'to',   with: 'feature'
+
+    click_button 'Compare'
+  end
+
+  step 'I see compared branches' do
+    expect(page).to have_content 'Commits (1)'
+    expect(page).to have_content 'Showing 1 changed file with 5 additions and 0 deletions'
+  end
+
+  step 'I see button to create a new merge request' do
+    expect(page).to have_link 'Create Merge Request'
+  end
+
+  step 'I should not see button to create a new merge request' do
+    expect(page).to_not have_link 'Create Merge Request'
+  end
+
+  step 'I should see button to the merge request' do
+    merge_request = MergeRequest.find_by(title: 'Feature')
+    expect(page).to have_link "View #{merge_request.to_reference}", href: namespace_project_merge_request_path(@project.namespace, @project, merge_request)
+  end
+
   step 'I see breadcrumb links' do
     expect(page).to have_selector('ul.breadcrumb')
     expect(page).to have_selector('ul.breadcrumb a', count: 4)