Merge branch 'zj-display-error-team-fetch' into 'master'

Fix inconsistent return type

Closes #27150

See merge request !8290

app/controllers/projects/mattermosts_controller.rb

@@ -34,7 +34,7 @@ class Projects::MattermostsController < Projects::ApplicationController
   end
 
   def teams
-    @teams ||= @service.list_teams(current_user)
+    @teams, @teams_error_message = @service.list_teams(current_user)
   end
 
   def service

app/models/project_services/mattermost_slash_commands_service.rb

@@ -28,8 +28,8 @@ class MattermostSlashCommandsService < ChatSlashCommandsService
     [false, e.message]
   end
 
-  def list_teams(user)
-    Mattermost::Team.new(user).all
+  def list_teams(current_user)
+    [Mattermost::Team.new(current_user).all, nil]
   rescue Mattermost::Error => e
     [[], e.message]
   end

app/views/projects/mattermosts/_no_teams.html.haml

+- if @teams_error_message
+  = content_for :flash_message do
+    .alert.alert-danger= @teams_error_message
+
 %p
   You aren’t a member of any team on the Mattermost instance at
   %strong= Gitlab.config.mattermost.host

spec/controllers/projects/mattermosts_controller_spec.rb

@@ -13,13 +13,13 @@ describe Projects::MattermostsController do
     before do
       allow_any_instance_of(MattermostSlashCommandsService).
         to receive(:list_teams).and_return([])
+    end
 
+    it 'accepts the request' do
       get(:new,
           namespace_id: project.namespace.to_param,
           project_id: project.to_param)
-    end
 
-    it 'accepts the request' do
       expect(response).to have_http_status(200)
     end
   end

spec/features/projects/services/mattermost_slash_command_spec.rb

@@ -99,6 +99,15 @@ feature 'Setup Mattermost slash commands', feature: true do
       expect(select_element.all('option').count).to eq(3)
     end
 
+    it 'shows an error alert with the error message if there is an error requesting teams' do
+      allow_any_instance_of(MattermostSlashCommandsService).to receive(:list_teams) { [[], 'test mattermost error message'] }
+
+      click_link 'Add to Mattermost'
+
+      expect(page).to have_selector('.alert')
+      expect(page).to have_content('test mattermost error message')
+    end
+
     def stub_teams(count: 0)
       teams = create_teams(count)
 

spec/models/project_services/mattermost_slash_commands_service_spec.rb

@@ -113,10 +113,7 @@ describe MattermostSlashCommandsService, :models do
         end
 
         it 'shows error messages' do
-          teams, message = subject
-
-          expect(teams).to be_empty
-          expect(message).to eq('Failed to get team list.')
+          expect(subject).to eq([[], "Failed to get team list."])
         end
       end
     end