Use `assert_empty` minitest helper

test/controllers/internal_helpers_test.rb

@@ -51,7 +51,7 @@ class HelpersTest < Devise::ControllerTestCase
   end
 
   test 'resources methods are not controller actions' do
-    assert @controller.class.action_methods.delete_if { |m| m.include? 'commenter' }.empty?
+    assert_empty @controller.class.action_methods.delete_if { |m| m.include? 'commenter' }
   end
 
   test 'require no authentication tests current mapping' do

test/integration/lockable_test.rb

@@ -99,7 +99,7 @@ class LockTest < Devise::IntegrationTest
 
     sign_in_as_user(password: "invalid")
     assert_contain 'Your account is locked.'
-    assert ActionMailer::Base.deliveries.empty?
+    assert_empty ActionMailer::Base.deliveries
   end
 
   test 'error message is configurable by resource name' do

test/integration/registerable_test.rb

@@ -268,7 +268,7 @@ class RegistrationTest < Devise::IntegrationTest
     click_button "Cancel my account"
     assert_contain "Bye! Your account has been successfully cancelled. We hope to see you again soon."
 
-    assert User.to_adapter.find_all.empty?
+    assert_empty User.to_adapter.find_all
   end
 
   test 'a user should be able to cancel sign up by deleting data in the session' do