Prevent merging an MR when namespace storage limits are exceeded

Return an error message

ee/app/services/ee/merge_requests/merge_base_service.rb

@@ -50,13 +50,23 @@ def hooks_validation_error(merge_request)
       private
 
       def check_size_limit
-        size_checker = merge_request.target_project.repository_size_checker
+        size_checker = target_project_size_checker
 
         if size_checker.above_size_limit?
           raise ::MergeRequests::MergeService::MergeError, size_checker.error_message.merge_error
         end
       end
 
+      def target_project_size_checker
+        root_namespace = merge_request.target_project.namespace.root_ancestor
+
+        if ::EE::Gitlab::Namespaces::Storage::Enforcement.enforce_limit?(root_namespace)
+          ::EE::Namespace::RootStorageSize.new(root_namespace)
+        else
+          merge_request.target_project.repository_size_checker
+        end
+      end
+
       def check_blocking_mrs
         return unless merge_request.merge_blocked_by_other_mrs?
 

ee/lib/ee/gitlab/namespace_storage_size_error_message.rb

@@ -15,6 +15,11 @@ def commit_error
         push_error
       end
 
+      def merge_error
+        "This merge request cannot be merged, because the namespace storage limit " \
+        "of #{formatted(limit)} has been reached."
+      end
+
       def push_error(change_size = 0)
         "Your push to this repository has been rejected because the namespace storage limit " \
         "of #{formatted(limit)} has been reached. " \

ee/spec/features/merge_request/user_merges_with_namespace_storage_limits_spec.rb

+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe "Merge request > User merges with namespace storage limits", :js, :saas, :sidekiq_inline do
+  include NamespaceStorageHelpers
+
+  let_it_be(:user) { create(:user) }
+  let_it_be(:group, refind: true) { create(:group) }
+
+  let!(:project) { create(:project, :repository, group: group) }
+  let!(:merge_request) { create(:merge_request, source_project: project) }
+
+  before_all do
+    create(:gitlab_subscription, :premium, namespace: group)
+    create(:namespace_root_storage_statistics, namespace: group)
+  end
+
+  before do
+    project.add_developer(user)
+    enforce_namespace_storage_limit(group)
+    set_storage_size_limit(group, megabytes: 10)
+    sign_in(user)
+  end
+
+  context 'when the namespace storage limit has not been exceeded' do
+    before do
+      set_used_storage(group, megabytes: 4)
+    end
+
+    it 'merges the merge request' do
+      visit(merge_request_path(merge_request))
+
+      click_merge_button
+
+      expect(page).to have_selector('.gl-badge', text: 'Merged')
+    end
+  end
+
+  context 'when the namespace storage limit has been exceeded' do
+    before do
+      set_used_storage(group, megabytes: 15)
+    end
+
+    it 'does not merge the merge request' do
+      visit(merge_request_path(merge_request))
+
+      click_merge_button
+
+      expect(page).to have_text(
+        'This merge request cannot be merged, because ' \
+        'the namespace storage limit of 10 MB has been reached'
+      )
+    end
+  end
+
+  def click_merge_button
+    page.within(".mr-state-widget") do
+      click_button("Merge")
+    end
+  end
+end

ee/spec/lib/ee/gitlab/namespace_storage_size_error_message_spec.rb

@@ -26,6 +26,15 @@
     end
   end
 
+  describe '#merge_error' do
+    it 'returns the expected message' do
+      expected_message = "This merge request cannot be merged, because " \
+        "the namespace storage limit of 10 MB has been reached."
+
+      expect(error_message.merge_error).to eq(expected_message)
+    end
+  end
+
   describe '#push_error' do
     it 'returns the expected message' do
       expected_message = "Your push to this repository has been rejected because " \

ee/spec/services/merge_requests/merge_service_spec.rb

@@ -3,6 +3,8 @@
 require 'spec_helper'
 
 RSpec.describe MergeRequests::MergeService do
+  include NamespaceStorageHelpers
+
   let(:user) { create(:user) }
   let(:merge_request) { create(:merge_request, :simple) }
   let(:project) { merge_request.project }
@@ -15,13 +17,82 @@
   describe '#execute' do
     context 'project has exceeded size limit' do
       before do
-        allow(project.repository_size_checker).to receive(:above_size_limit?).and_return(true)
+        project.update_attribute(:repository_size_limit, 5)
+        project.statistics.update!(repository_size: 8)
+      end
+
+      it 'persists the correct error message' do
+        service.execute(merge_request)
+
+        expect(merge_request.merge_error).to eq(
+          'This merge request cannot be merged, ' \
+          'because this repository has exceeded its size limit of 5 Bytes by 3 Bytes'
+        )
+      end
+    end
+
+    context 'when the namespace storage limit has been exceeded', :saas do
+      let(:namespace) { project.namespace }
+
+      before do
+        create(:gitlab_subscription, :premium, namespace: namespace)
+        create(:namespace_root_storage_statistics, namespace: namespace)
+        enforce_namespace_storage_limit(namespace)
+        set_storage_size_limit(namespace, megabytes: 4)
+        set_used_storage(namespace, megabytes: 5)
+      end
+
+      it 'persists the correct error message' do
+        service.execute(merge_request)
+
+        expect(merge_request.merge_error).to eq(
+          'This merge request cannot be merged, ' \
+          'because the namespace storage limit of 4 MB has been reached.'
+        )
+      end
+    end
+
+    context 'when the repository size limit has been exceeded, but the namespace storage limit has not', :saas do
+      let(:namespace) { project.namespace }
+
+      before do
+        project.update_attribute(:repository_size_limit, 5)
+        project.statistics.update!(repository_size: 6)
+        create(:gitlab_subscription, :premium, namespace: namespace)
+        create(:namespace_root_storage_statistics, namespace: namespace)
+        enforce_namespace_storage_limit(namespace)
+        set_storage_size_limit(namespace, megabytes: 10)
+        set_used_storage(namespace, megabytes: 7)
+      end
+
+      it 'does not set an error message' do
+        service.execute(merge_request)
+
+        expect(merge_request.merge_error).to be_nil
+      end
+    end
+
+    context 'when the namespace storage limit has been exceeded and the merge request is for a subgroup project', :saas do
+      let(:group) { create(:group) }
+      let(:subgroup) { create(:group, parent: group) }
+      let(:project) { create(:project, :repository, group: subgroup) }
+      let(:merge_request) { create(:merge_request, :simple, source_project: project) }
+
+      before do
+        create(:gitlab_subscription, :premium, namespace: group)
+        create(:namespace_root_storage_statistics, namespace: group)
+        enforce_namespace_storage_limit(group)
+        set_storage_size_limit(group, megabytes: 6)
+        set_used_storage(group, megabytes: 8)
       end
 
       it 'persists the correct error message' do
         service.execute(merge_request)
 
-        expect(merge_request.merge_error).to include('This merge request cannot be merged')
+        expect(merge_request.merge_error).to eq(
+          'This merge request cannot be merged, ' \
+          'because the namespace storage limit of 6 MB has been reached.'
+        )
       end
     end