1 files changed, 5 insertions, 6 deletions
diff --git a/activemodel/test/cases/errors_test.rb b/activemodel/test/cases/errors_test.rb
index fe351f922d..6ff3be1308 100644
--- a/activemodel/test/cases/errors_test.rb
+++ b/activemodel/test/cases/errors_test.rb
@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require "cases/helper"
-require "active_support/core_ext/string/strip"
 require "yaml"
 
 class ErrorsTest < ActiveModel::TestCase
@@ -208,26 +207,26 @@ class ErrorsTest < ActiveModel::TestCase
 
   test "added? returns false when no errors are present" do
     person = Person.new
-    assert !person.errors.added?(:name)
+    assert_not person.errors.added?(:name)
   end
 
   test "added? returns false when checking a nonexisting error and other errors are present for the given attribute" do
     person = Person.new
     person.errors.add(:name, "is invalid")
-    assert !person.errors.added?(:name, "cannot be blank")
+    assert_not person.errors.added?(:name, "cannot be blank")
   end
 
   test "added? returns false when checking for an error, but not providing message arguments" do
     person = Person.new
     person.errors.add(:name, "cannot be blank")
-    assert !person.errors.added?(:name)
+    assert_not person.errors.added?(:name)
   end
 
   test "added? returns false when checking for an error by symbol and a different error with same message is present" do
     I18n.backend.store_translations("en", errors: { attributes: { name: { wrong: "is wrong", used: "is wrong" } } })
     person = Person.new
     person.errors.add(:name, :wrong)
-    assert !person.errors.added?(:name, :used)
+    assert_not person.errors.added?(:name, :used)
   end
 
   test "size calculates the number of error messages" do
@@ -406,7 +405,7 @@ class ErrorsTest < ActiveModel::TestCase
   end
 
   test "errors are backward compatible with the Rails 4.2 format" do
-    yaml = <<-CODE.strip_heredoc
+    yaml = <<~CODE
     --- !ruby/object:ActiveModel::Errors
     base: &1 !ruby/object:ErrorsTest::Person
       errors: !ruby/object:ActiveModel::Errors