Expose paths needed in API

It is helpful to not duplicate these paths in the FE.

ee/app/presenters/ee/merge_request_presenter.rb

@@ -11,6 +11,30 @@ module EE
       end
     end
 
+    def api_approvals_path
+      if requires_approve?
+        api_v4_projects_merge_requests_approvals_path(id: project.id, merge_request_iid: merge_request.iid)
+      end
+    end
+
+    def api_approval_settings_path
+      if requires_approve?
+        api_v4_projects_merge_requests_approval_settings_path(id: project.id, merge_request_iid: merge_request.iid)
+      end
+    end
+
+    def api_approve_path
+      if requires_approve?
+        api_v4_projects_merge_requests_approve_path(id: project.id, merge_request_iid: merge_request.iid)
+      end
+    end
+
+    def api_unapprove_path
+      if requires_approve?
+        api_v4_projects_merge_requests_unapprove_path(id: project.id, merge_request_iid: merge_request.iid)
+      end
+    end
+
     def target_project
       merge_request.target_project.present(current_user: current_user)
     end

ee/app/serializers/ee/merge_request_widget_entity.rb

@@ -128,6 +128,18 @@ module EE
       expose :approvals_path do |merge_request|
         presenter(merge_request).approvals_path
       end
+      expose :api_approvals_path do |merge_request|
+        presenter(merge_request).api_approvals_path
+      end
+      expose :api_approval_settings_path do |merge_request|
+        presenter(merge_request).api_approval_settings_path
+      end
+      expose :api_approve_path do |merge_request|
+        presenter(merge_request).api_approve_path
+      end
+      expose :api_unapprove_path do |merge_request|
+        presenter(merge_request).api_unapprove_path
+      end
     end
 
     private

ee/spec/presenters/merge_request_presenter_spec.rb

@@ -13,6 +13,38 @@ describe MergeRequestPresenter do
     end
   end
 
+  describe '#api_approvals_path' do
+    subject { described_class.new(resource, current_user: user).api_approvals_path }
+
+    it 'returns path' do
+      is_expected.to eq("/api/v4/projects/#{resource.project.id}/merge_requests/#{resource.iid}/approvals")
+    end
+  end
+
+  describe '#api_approval_settings_path' do
+    subject { described_class.new(resource, current_user: user).api_approval_settings_path }
+
+    it 'returns path' do
+      is_expected.to eq("/api/v4/projects/#{resource.project.id}/merge_requests/#{resource.iid}/approval_settings")
+    end
+  end
+
+  describe '#api_approve_path' do
+    subject { described_class.new(resource, current_user: user).api_approve_path }
+
+    it 'returns path' do
+      is_expected.to eq("/api/v4/projects/#{resource.project.id}/merge_requests/#{resource.iid}/approve")
+    end
+  end
+
+  describe '#api_unapprove_path' do
+    subject { described_class.new(resource, current_user: user).api_unapprove_path }
+
+    it 'returns path' do
+      is_expected.to eq("/api/v4/projects/#{resource.project.id}/merge_requests/#{resource.iid}/unapprove")
+    end
+  end
+
   describe '#approvers_left' do
     let!(:private_group) { create(:group_with_members, :private) }
     let!(:public_group) { create(:group_with_members) }

spec/fixtures/api/schemas/entities/merge_request_widget.json

@@ -129,6 +129,10 @@
     "approvals_before_merge": { "type": ["integer", "null"] },
     "approved": { "type": "boolean" },
     "approvals_path": { "type": ["string", "null"] },
+    "api_approvals_path": { "type": ["string", "null"] },
+    "api_approval_settings_path": { "type": ["string", "null"] },
+    "api_approve_path": { "type": ["string", "null"] },
+    "api_unapprove_path": { "type": ["string", "null"] },
     "codeclimate": {
       "head_path": { "type": "string" },
       "base_path": { "type": "string" }