Unassign all Issues and Merge Requests when member leaves team

app/services/members/authorized_destroy_service.rb

@@ -9,7 +9,11 @@ module Members
     def execute
       return false if member.is_a?(GroupMember) && member.source.last_owner?(member.user)
 
-      member.destroy
+      Member.transaction do
+        unassign_issues_and_merge_requests(member)
+
+        member.destroy
+      end
 
       if member.request? && member.user != user
         notification_service.decline_access_request(member)
@@ -17,5 +21,22 @@ module Members
 
       member
     end
+
+    private
+
+    def unassign_issues_and_merge_requests(member)
+      if member.is_a?(GroupMember)
+        IssuesFinder.new(user, group_id: member.source_id, assignee_id: member.user_id).
+          execute.
+          update_all(assignee_id: nil)
+        MergeRequestsFinder.new(user, group_id: member.source_id, assignee_id: member.user_id).
+          execute.
+          update_all(assignee_id: nil)
+      else
+        project = member.source
+        project.issues.opened.assigned_to(member.user).update_all(assignee_id: nil)
+        project.merge_requests.opened.assigned_to(member.user).update_all(assignee_id: nil)
+      end
+    end
   end
 end

spec/services/members/authorized_destroy_service_spec.rb

+require 'spec_helper'
+
+describe Members::AuthorizedDestroyService, services: true do
+  let(:user) { create(:user) }
+  let(:member_user) { create(:user) }
+  let(:project) { create(:empty_project, :public) }
+  let(:group) { create(:group, :public) }
+  let(:group_project) { create(:empty_project, :public, group: group) }
+
+  def number_of_assigned_issuables(user)
+    user.assigned_issues.count + user.assigned_merge_requests.count
+  end
+
+  context 'Group member' do
+    it "unassigns issues and merge requests" do
+      group.add_developer(member_user)
+
+      issue = create :issue, project: group_project, assignee: member_user
+      create :issue, assignee: member_user
+      merge_request = create :merge_request, target_project: group_project, source_project: group_project, assignee: member_user
+      create :merge_request, target_project: project, source_project: project, assignee: member_user
+
+      member = group.members.find_by(user_id: member_user.id)
+
+      expect{ described_class.new(member, member_user).execute }
+        .to change{ number_of_assigned_issuables(member_user) }.from(4).to(2)
+
+      expect(issue.reload.assignee_id).to be_nil
+      expect(merge_request.reload.assignee_id).to be_nil
+    end
+  end
+
+  context 'Project member' do
+    it "unassigns issues and merge requests" do
+      project.team << [member_user, :developer]
+
+      create :issue, project: project, assignee: member_user
+      create :merge_request, target_project: project, source_project: project, assignee: member_user
+
+      member = project.members.find_by(user_id: member_user.id)
+
+      expect{ described_class.new(member, member_user).execute }
+        .to change{ number_of_assigned_issuables(member_user) }.from(2).to(0)
+    end
+  end
+end