New API: share project with group

Share project with group using API.
You must be a master or owner of project in order to do it.

POST /projects/:id/share

Parameters:
  id (required) - The ID of a project
  group_id (required) - The ID of a group
  group_access (required) - Level of permissions for sharing

lib/api/entities.rb

@@ -140,5 +140,9 @@ module API
     class LdapGroup < Grape::Entity
       expose :cn
     end
+
+    class ProjectGroupLink < Grape::Entity
+      expose :id, :project_id, :group_id, :group_access
+    end
   end
 end

lib/api/projects.rb

@@ -262,6 +262,29 @@ module API
           {message: "Access revoked", id: params[:user_id].to_i}
         end
       end
+
+      # Share project with group
+      #
+      # Parameters:
+      #   id (required) - The ID of a project
+      #   group_id (required) - The ID of a group
+      #   group_access (required) - Level of permissions for sharing
+      #
+      # Example Request:
+      #   POST /projects/:id/share
+      post ":id/share" do
+        authorize! :admin_project, user_project
+        required_attributes! [:group_id, :group_access]
+
+        link = user_project.project_group_links.new
+        link.group_id = params[:group_id]
+        link.group_access = params[:group_access]
+        if link.save
+          present link, with: Entities::ProjectGroupLink
+        else
+          render_api_error!(link.errors.full_messages.first, 409)
+        end
+      end
     end
   end
 end

spec/requests/api/projects_spec.rb

@@ -692,4 +692,35 @@ describe API::API do
       end
     end
   end
+
+  describe "POST /projects/:id/share" do
+    let(:group) { create(:group) }
+
+    it "should share project with group" do
+      expect {
+        post api("/projects/#{project.id}/share", user), group_id: group.id,
+          group_access: Gitlab::Access::DEVELOPER
+      }.to change { ProjectGroupLink.count }.by(1)
+
+      response.status.should == 201
+      json_response['group_id'].should == group.id
+      json_response['group_access'].should == Gitlab::Access::DEVELOPER
+    end
+
+    it "should return a 400 error when group id is not given" do
+      post api("/projects/#{project.id}/share", user), group_access: Gitlab::Access::DEVELOPER
+      response.status.should == 400
+    end
+
+    it "should return a 400 error when access level is not given" do
+      post api("/projects/#{project.id}/share", user), group_id: group.id
+      response.status.should == 400
+    end
+
+    it "should return a 409 error when wrong params passed" do
+      post api("/projects/#{project.id}/share", user), group_id: group.id, group_access: 1234
+      response.status.should == 409
+      json_response['message'].should == 'Group access is not included in the list'
+    end
+  end
 end