Merge branch 'jprovazn-rebase' into 'master'

Backport 'Rebase' feature from EE to CE

Closes #40301

See merge request gitlab-org/gitlab-ce!16071

11 files changed, 480 insertions, 7 deletions

diff --git a/spec/controllers/projects/merge_requests_controller_spec.rb b/spec/controllers/projects/merge_requests_controller_spec.rb
index 45c424af8c4..c8cc6b374f6 100644
--- a/spec/controllers/projects/merge_requests_controller_spec.rb
+++ b/spec/controllers/projects/merge_requests_controller_spec.rb
@@ -684,4 +684,62 @@ describe Projects::MergeRequestsController do
                             format: :json
     end
   end
+
+  describe 'POST #rebase' do
+    let(:viewer)        { user }
+
+    def post_rebase
+      post :rebase, namespace_id: project.namespace, project_id: project, id: merge_request
+    end
+
+    def expect_rebase_worker_for(user)
+      expect(RebaseWorker).to receive(:perform_async).with(merge_request.id, user.id)
+    end
+
+    context 'successfully' do
+      it 'enqeues a RebaseWorker' do
+        expect_rebase_worker_for(viewer)
+
+        post_rebase
+
+        expect(response.status).to eq(200)
+      end
+    end
+
+    context 'with a forked project' do
+      let(:fork_project) { create(:project, :repository, forked_from_project: project) }
+      let(:fork_owner) { fork_project.owner }
+
+      before do
+        merge_request.update!(source_project: fork_project)
+        fork_project.add_reporter(user)
+      end
+
+      context 'user cannot push to source branch' do
+        it 'returns 404' do
+          expect_rebase_worker_for(viewer).never
+
+          post_rebase
+
+          expect(response.status).to eq(404)
+        end
+      end
+
+      context 'user can push to source branch' do
+        before do
+          project.add_reporter(fork_owner)
+
+          sign_in(fork_owner)
+        end
+
+        it 'returns 200' do
+          expect_rebase_worker_for(fork_owner)
+
+          post_rebase
+
+          expect(response.status).to eq(200)
+        end
+      end
+    end
+  end
 end
diff --git a/spec/fixtures/api/schemas/entities/merge_request_basic.json b/spec/fixtures/api/schemas/entities/merge_request_basic.json
index 995f13381ad..f1199468d53 100644
--- a/spec/fixtures/api/schemas/entities/merge_request_basic.json
+++ b/spec/fixtures/api/schemas/entities/merge_request_basic.json
@@ -9,6 +9,7 @@
     "human_time_estimate": { "type": ["string", "null"] },
     "human_total_time_spent": { "type": ["string", "null"] },
     "merge_error": { "type": ["string", "null"] },
+    "rebase_in_progress": { "type": "boolean" },
     "assignee_id": { "type": ["integer", "null"] },
     "subscribed": { "type": ["boolean", "null"] },
     "participants": { "type": "array" }
diff --git a/spec/fixtures/api/schemas/entities/merge_request_widget.json b/spec/fixtures/api/schemas/entities/merge_request_widget.json
index 9de27bee751..7f662098216 100644
--- a/spec/fixtures/api/schemas/entities/merge_request_widget.json
+++ b/spec/fixtures/api/schemas/entities/merge_request_widget.json
@@ -103,7 +103,11 @@
     "remove_source_branch": { "type": ["boolean", "null"] },
     "merge_ongoing": { "type": "boolean" },
     "ff_only_enabled": { "type": ["boolean", false] },
-    "should_be_rebased": { "type": "boolean" }
+    "should_be_rebased": { "type": "boolean" },
+    "rebase_commit_sha": { "type": ["string", "null"] },
+    "rebase_in_progress": { "type": "boolean" },
+    "can_push_to_source_branch": { "type": "boolean" },
+    "rebase_path": { "type": ["string", "null"] }
   },
   "additionalProperties": false
 }
diff --git a/spec/javascripts/vue_mr_widget/components/mr_widget_rebase_spec.js b/spec/javascripts/vue_mr_widget/components/mr_widget_rebase_spec.js
new file mode 100644
index 00000000000..66ecaa316c8
--- /dev/null
+++ b/spec/javascripts/vue_mr_widget/components/mr_widget_rebase_spec.js
@@ -0,0 +1,115 @@
+import Vue from 'vue';
+import eventHub from '~/vue_merge_request_widget/event_hub';
+import component from '~/vue_merge_request_widget/components/states/mr_widget_rebase.vue';
+import mountComponent from '../../helpers/vue_mount_component_helper';
+
+describe('Merge request widget rebase component', () => {
+  let Component;
+  let vm;
+  beforeEach(() => {
+    Component = Vue.extend(component);
+  });
+
+  afterEach(() => {
+    vm.$destroy();
+  });
+
+  describe('While rebasing', () => {
+    it('should show progress message', () => {
+      vm = mountComponent(Component, {
+        mr: { rebaseInProgress: true },
+        service: {},
+      });
+
+      expect(
+        vm.$el.querySelector('.rebase-state-find-class-convention span').textContent.trim(),
+      ).toContain('Rebase in progress');
+    });
+  });
+
+  describe('With permissions', () => {
+    beforeEach(() => {
+      vm = mountComponent(Component, {
+        mr: {
+          rebaseInProgress: false,
+          canPushToSourceBranch: true,
+        },
+        service: {},
+      });
+    });
+
+    it('it should render rebase button and warning message', () => {
+      const text = vm.$el.querySelector('.rebase-state-find-class-convention span').textContent.trim();
+      expect(text).toContain('Fast-forward merge is not possible.');
+      expect(text).toContain('Rebase the source branch onto the target branch or merge target');
+      expect(text).toContain('branch into source branch to allow this merge request to be merged.');
+    });
+
+    it('it should render error message when it fails', (done) => {
+      vm.rebasingError = 'Something went wrong!';
+
+      Vue.nextTick(() => {
+        expect(
+          vm.$el.querySelector('.rebase-state-find-class-convention span').textContent.trim(),
+        ).toContain('Something went wrong!');
+        done();
+      });
+    });
+  });
+
+  describe('Without permissions', () => {
+    it('should render a message explaining user does not have permissions', () => {
+      vm = mountComponent(Component, {
+        mr: {
+          rebaseInProgress: false,
+          canPushToSourceBranch: false,
+          targetBranch: 'foo',
+        },
+        service: {},
+      });
+
+      const text = vm.$el.querySelector('.rebase-state-find-class-convention span').textContent.trim();
+
+      expect(text).toContain('Fast-forward merge is not possible.');
+      expect(text).toContain('Rebase the source branch onto');
+      expect(text).toContain('foo');
+      expect(text).toContain('to allow this merge request to be merged.');
+    });
+  });
+
+  describe('methods', () => {
+    it('checkRebaseStatus', (done) => {
+      spyOn(eventHub, '$emit');
+      vm = mountComponent(Component, {
+        mr: {},
+        service: {
+          rebase() {
+            return Promise.resolve();
+          },
+          poll() {
+            return Promise.resolve({
+              data: {
+                rebase_in_progress: false,
+                merge_error: null,
+              },
+            });
+          },
+        },
+      });
+
+      vm.rebase();
+
+      // Wait for the rebase request
+      vm.$nextTick()
+        // Wait for the polling request
+        .then(vm.$nextTick())
+        // Wait for the eventHub to be called
+        .then(vm.$nextTick())
+        .then(() => {
+          expect(eventHub.$emit).toHaveBeenCalledWith('MRWidgetUpdateRequested');
+        })
+        .then(done)
+        .catch(done.fail);
+    });
+  });
+});
diff --git a/spec/models/merge_request_spec.rb b/spec/models/merge_request_spec.rb
index d8ebd46faab..07b3e1c1758 100644
--- a/spec/models/merge_request_spec.rb
+++ b/spec/models/merge_request_spec.rb
@@ -1903,4 +1903,50 @@ describe MergeRequest do
       end
     end
   end
+
+  describe '#should_be_rebased?' do
+    let(:project) { create(:project, :repository) }
+
+    it 'returns false for the same source and target branches' do
+      merge_request = create(:merge_request, source_project: project, target_project: project)
+
+      expect(merge_request.should_be_rebased?).to be_falsey
+    end
+  end
+
+  describe '#rebase_in_progress?' do
+    # Create merge request and project before we stub file calls
+    before do
+      subject
+    end
+
+    it 'returns true when there is a current rebase directory' do
+      allow(File).to receive(:exist?).and_return(true)
+      allow(File).to receive(:mtime).and_return(Time.now)
+
+      expect(subject.rebase_in_progress?).to be_truthy
+    end
+
+    it 'returns false when there is no rebase directory' do
+      allow(File).to receive(:exist?).and_return(false)
+
+      expect(subject.rebase_in_progress?).to be_falsey
+    end
+
+    it 'returns false when the rebase directory has expired' do
+      allow(File).to receive(:exist?).and_return(true)
+      allow(File).to receive(:mtime).and_return(20.minutes.ago)
+
+      expect(subject.rebase_in_progress?).to be_falsey
+    end
+
+    it 'returns false when the source project has been removed' do
+      allow(subject).to receive(:source_project).and_return(nil)
+      allow(File).to receive(:exist?).and_return(true)
+      allow(File).to receive(:mtime).and_return(Time.now)
+
+      expect(File).not_to have_received(:exist?)
+      expect(subject.rebase_in_progress?).to be_falsey
+    end
+  end
 end
diff --git a/spec/models/project_spec.rb b/spec/models/project_spec.rb
index 723677ce996..32f40f8c365 100644
--- a/spec/models/project_spec.rb
+++ b/spec/models/project_spec.rb
@@ -418,14 +418,21 @@ describe Project do
   end
 
   describe '#merge_method' do
-    it 'returns "ff" merge_method when ff is enabled' do
-      project = build(:project, merge_requests_ff_only_enabled: true)
-      expect(project.merge_method).to be :ff
+    using RSpec::Parameterized::TableSyntax
+
+    where(:ff, :rebase, :method) do
+      true  | true  | :ff
+      true  | false | :ff
+      false | true  | :rebase_merge
+      false | false | :merge
     end
 
-    it 'returns "merge" merge_method when ff is disabled' do
-      project = build(:project, merge_requests_ff_only_enabled: false)
-      expect(project.merge_method).to be :merge
+    with_them do
+      let(:project) { build(:project, merge_requests_rebase_enabled: rebase, merge_requests_ff_only_enabled: ff) }
+
+      subject { project.merge_method }
+
+      it { is_expected.to eq(method) }
     end
   end
 
diff --git a/spec/presenters/merge_request_presenter_spec.rb b/spec/presenters/merge_request_presenter_spec.rb
index 969c4753f33..e3b37739e8e 100644
--- a/spec/presenters/merge_request_presenter_spec.rb
+++ b/spec/presenters/merge_request_presenter_spec.rb
@@ -404,4 +404,67 @@ describe MergeRequestPresenter do
         .to eq("<a href=\"/#{resource.source_project.full_path}/tree/#{resource.source_branch}\">#{resource.source_branch}</a>")
     end
   end
+
+  describe '#rebase_path' do
+    before do
+      allow(resource).to receive(:rebase_in_progress?) { rebase_in_progress }
+      allow(resource).to receive(:should_be_rebased?) { should_be_rebased }
+
+      allow_any_instance_of(Gitlab::UserAccess::RequestCacheExtension)
+        .to receive(:can_push_to_branch?)
+        .with(resource.source_branch)
+        .and_return(can_push_to_branch)
+    end
+
+    subject do
+      described_class.new(resource, current_user: user).rebase_path
+    end
+
+    context 'when can rebase' do
+      let(:rebase_in_progress) { false }
+      let(:can_push_to_branch) { true }
+      let(:should_be_rebased) { true }
+
+      before do
+        allow(resource).to receive(:source_branch_exists?) { true }
+      end
+
+      it 'returns path' do
+        is_expected
+          .to eq("/#{project.full_path}/merge_requests/#{resource.iid}/rebase")
+      end
+    end
+
+    context 'when cannot rebase' do
+      context 'when rebase in progress' do
+        let(:rebase_in_progress) { true }
+        let(:can_push_to_branch) { true }
+        let(:should_be_rebased) { true }
+
+        it 'returns nil' do
+          is_expected.to be_nil
+        end
+      end
+
+      context 'when user cannot merge' do
+        let(:rebase_in_progress) { false }
+        let(:can_push_to_branch) { false }
+        let(:should_be_rebased) { true }
+
+        it 'returns nil' do
+          is_expected.to be_nil
+        end
+      end
+
+      context 'should not be rebased' do
+        let(:rebase_in_progress) { false }
+        let(:can_push_to_branch) { true }
+        let(:should_be_rebased) { false }
+
+        it 'returns nil' do
+          is_expected.to be_nil
+        end
+      end
+    end
+  end
 end
diff --git a/spec/serializers/merge_request_widget_entity_spec.rb b/spec/serializers/merge_request_widget_entity_spec.rb
index e25552eb0d8..80a271ba7fb 100644
--- a/spec/serializers/merge_request_widget_entity_spec.rb
+++ b/spec/serializers/merge_request_widget_entity_spec.rb
@@ -190,4 +190,20 @@ describe MergeRequestWidgetEntity do
       end
     end
   end
+
+  describe 'when source project is deleted' do
+    let(:project) { create(:project, :repository) }
+    let(:fork_project) { create(:project, :repository, forked_from_project: project) }
+    let(:merge_request) { create(:merge_request, source_project: fork_project, target_project: project) }
+
+    it 'returns a blank rebase_path' do
+      allow(merge_request).to receive(:should_be_rebased?).and_return(true)
+      fork_project.destroy
+      merge_request.reload
+
+      entity = described_class.new(merge_request, request: request).as_json
+
+      expect(entity[:rebase_path]).to be_nil
+    end
+  end
 end
diff --git a/spec/services/merge_requests/rebase_service_spec.rb b/spec/services/merge_requests/rebase_service_spec.rb
new file mode 100644
index 00000000000..d1b37cdd073
--- /dev/null
+++ b/spec/services/merge_requests/rebase_service_spec.rb
@@ -0,0 +1,134 @@
+require 'spec_helper'
+
+describe MergeRequests::RebaseService do
+  include ProjectForksHelper
+
+  let(:user) { create(:user) }
+  let(:merge_request) do
+    create(:merge_request,
+           source_branch: 'feature_conflict',
+           target_branch: 'master')
+  end
+  let(:project) { merge_request.project }
+  let(:repository) { project.repository.raw }
+
+  subject(:service) { described_class.new(project, user, {}) }
+
+  before do
+    project.add_master(user)
+  end
+
+  describe '#execute' do
+    context 'when another rebase is already in progress' do
+      before do
+        allow(merge_request).to receive(:rebase_in_progress?).and_return(true)
+      end
+
+      it 'saves the error message' do
+        subject.execute(merge_request)
+
+        expect(merge_request.reload.merge_error).to eq 'Rebase task canceled: Another rebase is already in progress'
+      end
+
+      it 'returns an error' do
+        expect(service.execute(merge_request)).to match(status: :error,
+                                                        message: 'Failed to rebase. Should be done manually')
+      end
+    end
+
+    context 'when unexpected error occurs' do
+      before do
+        allow(repository).to receive(:run_git!).and_raise('Something went wrong')
+      end
+
+      it 'saves the error message' do
+        subject.execute(merge_request)
+
+        expect(merge_request.reload.merge_error).to eq 'Something went wrong'
+      end
+
+      it 'returns an error' do
+        expect(service.execute(merge_request)).to match(status: :error,
+                                                        message: 'Failed to rebase. Should be done manually')
+      end
+    end
+
+    context 'with git command failure' do
+      before do
+        allow(repository).to receive(:run_git!).and_raise(Gitlab::Git::Repository::GitError, 'Something went wrong')
+      end
+
+      it 'saves the error message' do
+        subject.execute(merge_request)
+
+        expect(merge_request.reload.merge_error).to eq 'Something went wrong'
+      end
+
+      it 'returns an error' do
+        expect(service.execute(merge_request)).to match(status: :error,
+                                                        message: 'Failed to rebase. Should be done manually')
+      end
+    end
+
+    context 'valid params' do
+      before do
+        service.execute(merge_request)
+      end
+
+      it 'rebases source branch' do
+        parent_sha = merge_request.source_project.repository.commit(merge_request.source_branch).parents.first.sha
+        target_branch_sha = merge_request.target_project.repository.commit(merge_request.target_branch).sha
+        expect(parent_sha).to eq(target_branch_sha)
+      end
+
+      it 'records the new SHA on the merge request' do
+        head_sha = merge_request.source_project.repository.commit(merge_request.source_branch).sha
+        expect(merge_request.reload.rebase_commit_sha).to eq(head_sha)
+      end
+
+      it 'logs correct author and commiter' do
+        head_commit = merge_request.source_project.repository.commit(merge_request.source_branch)
+
+        expect(head_commit.author_email).to eq('dmitriy.zaporozhets@gmail.com')
+        expect(head_commit.author_name).to eq('Dmitriy Zaporozhets')
+        expect(head_commit.committer_email).to eq(user.email)
+        expect(head_commit.committer_name).to eq(user.name)
+      end
+
+      context 'git commands' do
+        it 'sets GL_REPOSITORY env variable when calling git commands' do
+          expect(repository).to receive(:popen).exactly(3)
+            .with(anything, anything, hash_including('GL_REPOSITORY'))
+            .and_return(['', 0])
+
+          service.execute(merge_request)
+        end
+      end
+
+      context 'fork' do
+        let(:forked_project) do
+          fork_project(project, user, repository: true)
+        end
+
+        let(:merge_request_from_fork) do
+          forked_project.repository.create_file(
+            user,
+            'new-file-to-target',
+            '',
+            message: 'Add new file to target',
+            branch_name: 'master')
+
+          create(:merge_request,
+                 source_branch: 'master', source_project: forked_project,
+                 target_branch: 'master', target_project: project)
+        end
+
+        it 'rebases source branch' do
+          parent_sha = forked_project.repository.commit(merge_request_from_fork.source_branch).parents.first.sha
+          target_branch_sha = project.repository.commit(merge_request_from_fork.target_branch).sha
+          expect(parent_sha).to eq(target_branch_sha)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/views/projects/merge_requests/show.html.haml_spec.rb b/spec/views/projects/merge_requests/show.html.haml_spec.rb
index 28d54c2fb77..264e0ce0b40 100644
--- a/spec/views/projects/merge_requests/show.html.haml_spec.rb
+++ b/spec/views/projects/merge_requests/show.html.haml_spec.rb
@@ -54,6 +54,8 @@ describe 'projects/merge_requests/show.html.haml' do
     it 'closes the merge request if the source project does not exist' do
       closed_merge_request.update_attributes(state: 'open')
       forked_project.destroy
+      # Reload merge request so MergeRequest#source_project turns to `nil`
+      closed_merge_request.reload
 
       render
 
diff --git a/spec/workers/rebase_worker_spec.rb b/spec/workers/rebase_worker_spec.rb
new file mode 100644
index 00000000000..20aff020dbb
--- /dev/null
+++ b/spec/workers/rebase_worker_spec.rb
@@ -0,0 +1,27 @@
+require 'spec_helper'
+
+describe RebaseWorker, '#perform' do
+  context 'when rebasing an MR from a fork where upstream has protected branches' do
+    let(:upstream_project) { create(:project, :repository) }
+    let(:fork_project) { create(:project, :repository) }
+
+    let(:merge_request) do
+      create(:merge_request,
+             source_project: fork_project,
+             source_branch: 'feature_conflict',
+             target_project: upstream_project,
+             target_branch: 'master')
+    end
+
+    before do
+      create(:forked_project_link, forked_to_project: fork_project, forked_from_project: upstream_project)
+    end
+
+    it 'sets the correct project for running hooks' do
+      expect(MergeRequests::RebaseService)
+        .to receive(:new).with(fork_project, merge_request.author).and_call_original
+
+      subject.perform(merge_request, merge_request.author)
+    end
+  end
+end