Maintenance: Gem dependency psych update causes encoding issue to be fixed. Changed test case to ensure special unicode chars are handled properly.

db/migrate/20180911064647_issue_2140_reset_ldap_config.rb

@@ -1,3 +1,6 @@
+# ATTENTION: This migration is most likely not required anymore
+# because the encoding error was fixed by using a newer version of the psych gem (3.1.0).
+# However, we'll keep it as a regression test.
 class Issue2140ResetLdapConfig < ActiveRecord::Migration[5.1]
   def up
     # return if it's a new setup

spec/db/migrate/issue_2140_reset_ldap_config_spec.rb

@@ -17,7 +17,7 @@ RSpec.describe Issue2140ResetLdapConfig, type: :db_migration do
     end
   end
 
-  context 'when LDAP config is broken' do
+  context 'when LDAP config was assumed to be broken' do
     let(:config) do
       { 'wizardData' =>
                         { 'backend_user_attributes' =>
@@ -26,10 +26,8 @@ RSpec.describe Issue2140ResetLdapConfig, type: :db_migration do
                                                        { 'baz' => 'qux' } } }.with_indifferent_access
     end
 
-    it 'removes the offending backend_user_attributes sub-hash' do
-      expect { migrate }
-        .to change { Setting.get('ldap_config') }
-        .to(config.tap { |c| c[:wizardData].delete(:backend_user_attributes) })
+    it 'makes no changes' do
+      expect { migrate }.not_to change { Setting.get('ldap_config') }
     end
   end
 end