api for generating new merge request

DRY code + fix rubocop

Add more test cases

Append to changelog

DRY changes list

find_url service for merge_requests

use GET for getting merge request links

remove files

rename to get_url_service

reduce loop

add test case for cross project

refactor tiny thing

update changelog

3 files changed, 148 insertions, 0 deletions

diff --git a/spec/lib/gitlab/changes_list_spec.rb b/spec/lib/gitlab/changes_list_spec.rb
new file mode 100644
index 00000000000..69d86144e32
--- /dev/null
+++ b/spec/lib/gitlab/changes_list_spec.rb
@@ -0,0 +1,30 @@
+require "spec_helper"
+
+describe Gitlab::ChangesList do
+  let(:valid_changes_string) { "\n000000 570e7b2 refs/heads/my_branch\nd14d6c 6fd24d refs/heads/master" }
+  let(:invalid_changes) { 1 }
+
+  context 'when changes is a valid string' do
+    let(:changes_list) { Gitlab::ChangesList.new(valid_changes_string) }
+
+    it 'splits elements by newline character' do
+      expect(changes_list).to contain_exactly({
+        oldrev: "000000",
+        newrev: "570e7b2",
+        ref: "refs/heads/my_branch"
+      }, {
+        oldrev: "d14d6c",
+        newrev: "6fd24d",
+        ref: "refs/heads/master"
+      })
+    end
+
+    it 'behaves like a list' do
+      expect(changes_list.first).to eq({
+        oldrev: "000000",
+        newrev: "570e7b2",
+        ref: "refs/heads/my_branch"
+      })
+    end
+  end
+end
diff --git a/spec/requests/api/internal_spec.rb b/spec/requests/api/internal_spec.rb
index f6f85d6e95e..be52f88831f 100644
--- a/spec/requests/api/internal_spec.rb
+++ b/spec/requests/api/internal_spec.rb
@@ -275,6 +275,24 @@ describe API::API, api: true  do
     end
   end
 
+  describe 'GET /internal/merge_request_urls' do
+    let(:repo_name) { "#{project.namespace.name}/#{project.path}" }
+    let(:changes) { URI.escape("#{Gitlab::Git::BLANK_SHA} 570e7b2abdd848b95f2f578043fc23bd6f6fd24d refs/heads/new_branch") }
+
+    before do
+      project.team << [user, :developer]
+      get api("/internal/merge_request_urls?project=#{repo_name}&changes=#{changes}"), secret_token: secret_token
+    end
+
+    it 'returns link to create new merge request' do
+      expect(json_response).to match [{
+        "branch_name" => "new_branch",
+        "url" => "http://localhost/#{project.namespace.name}/#{project.path}/merge_requests/new?merge_request%5Bsource_branch%5D=new_branch",
+        "new_merge_request" => true
+      }]
+    end
+  end
+
   def pull(key, project, protocol = 'ssh')
     post(
       api("/internal/allowed"),
diff --git a/spec/services/merge_requests/get_urls_service_spec.rb b/spec/services/merge_requests/get_urls_service_spec.rb
new file mode 100644
index 00000000000..ec26770c3eb
--- /dev/null
+++ b/spec/services/merge_requests/get_urls_service_spec.rb
@@ -0,0 +1,100 @@
+require "spec_helper"
+
+describe MergeRequests::GetUrlsService do
+  let(:project) { create(:project, :public) }
+  let(:service) { MergeRequests::GetUrlsService.new(project) }
+  let(:source_branch) { "my_branch" }
+  let(:new_merge_request_url) { "http://localhost/#{project.namespace.name}/#{project.path}/merge_requests/new?merge_request%5Bsource_branch%5D=#{source_branch}" }
+  let(:show_merge_request_url) { "http://localhost/#{project.namespace.name}/#{project.path}/merge_requests/#{merge_request.iid}" }
+  let(:new_branch_changes) { "#{Gitlab::Git::BLANK_SHA} 570e7b2abdd848b95f2f578043fc23bd6f6fd24d refs/heads/#{source_branch}" }
+  let(:existing_branch_changes) { "d14d6c0abdd253381df51a723d58691b2ee1ab08 570e7b2abdd848b95f2f578043fc23bd6f6fd24d refs/heads/#{source_branch}" }
+
+  describe "#execute" do
+    shared_examples 'new_merge_request_link' do
+      it 'returns url to create new merge request' do
+        result = service.execute(changes)
+        expect(result).to match([{
+          branch_name: source_branch,
+          url: new_merge_request_url,
+          new_merge_request: true
+        }])
+      end
+    end
+
+    shared_examples 'show_merge_request_url' do
+      it 'returns url to view merge request' do
+        result = service.execute(changes)
+        expect(result).to match([{
+          branch_name: source_branch,
+          url: show_merge_request_url,
+          new_merge_request: false
+        }])
+      end
+    end
+
+    context 'pushing one completely new branch' do
+      let(:changes) { new_branch_changes }
+      it_behaves_like 'new_merge_request_link'
+    end
+
+    context 'pushing to existing branch but no merge request' do
+      let(:changes) { existing_branch_changes }
+      it_behaves_like 'new_merge_request_link'
+    end
+
+    context 'pushing to existing branch and merge request opened' do
+      let!(:merge_request) { create(:merge_request, source_project: project, source_branch: source_branch) }
+      let(:changes) { existing_branch_changes }
+      it_behaves_like 'show_merge_request_url'
+    end
+
+    context 'pushing to existing branch and merge request is reopened' do
+      let!(:merge_request) { create(:merge_request, :reopened, source_project: project, source_branch: source_branch) }
+      let(:changes) { existing_branch_changes }
+      it_behaves_like 'show_merge_request_url'
+    end
+
+    context 'pushing to existing branch from forked project' do
+      let(:user) { create(:user) }
+      let!(:forked_project) { Projects::ForkService.new(project, user).execute }
+      let!(:merge_request) { create(:merge_request, source_project: forked_project, target_project: project, source_branch: source_branch) }
+      let(:changes) { existing_branch_changes }
+      # Source project is now the forked one
+      let(:service) { MergeRequests::GetUrlsService.new(forked_project) }
+      it_behaves_like 'show_merge_request_url'
+    end
+
+    context 'pushing to existing branch and merge request is closed' do
+      let!(:merge_request) { create(:merge_request, :closed, source_project: project, source_branch: source_branch) }
+      let(:changes) { existing_branch_changes }
+      it_behaves_like 'new_merge_request_link'
+    end
+
+    context 'pushing to existing branch and merge request is merged' do
+      let!(:merge_request) { create(:merge_request, :merged, source_project: project, source_branch: source_branch) }
+      let(:changes) { existing_branch_changes }
+      it_behaves_like 'new_merge_request_link'
+    end
+
+    context 'pushing new branch and existing branch (with merge request created) at once' do
+      let!(:merge_request) { create(:merge_request, source_project: project, source_branch: "existing_branch") }
+      let(:new_branch_changes) { "#{Gitlab::Git::BLANK_SHA} 570e7b2abdd848b95f2f578043fc23bd6f6fd24d refs/heads/new_branch" }
+      let(:existing_branch_changes) { "d14d6c0abdd253381df51a723d58691b2ee1ab08 570e7b2abdd848b95f2f578043fc23bd6f6fd24d refs/heads/existing_branch" }
+      let(:changes) { "#{new_branch_changes}\n#{existing_branch_changes}" }
+      let(:new_merge_request_url) { "http://localhost/#{project.namespace.name}/#{project.path}/merge_requests/new?merge_request%5Bsource_branch%5D=new_branch" }
+
+      it 'returns 2 urls for both creating new and showing merge request' do
+        result = service.execute(changes)
+        expect(result).to match([{
+          branch_name: "new_branch",
+          url: new_merge_request_url,
+          new_merge_request: true
+        }, {
+          branch_name: "existing_branch",
+          url: show_merge_request_url,
+          new_merge_request: false
+        }])
+      end
+    end
+  end
+end