Merge branch 'casecmp-cop' into 'master'

Enable Rubocop Casecmp Performance Cop.

Also fixes the errors caused by enabling the cop.

`casecmp` is more performant than `.downcase` and `==`.

See also: https://github.com/bbatsov/rubocop/blob/master/lib/rubocop/cop/performance/casecmp.rb

See merge request !3957

2 files changed, 3 insertions, 3 deletions

diff --git a/lib/gitlab/database.rb b/lib/gitlab/database.rb
index 6f9da69983a..42bec913a45 100644
--- a/lib/gitlab/database.rb
+++ b/lib/gitlab/database.rb
@@ -5,11 +5,11 @@ module Gitlab
     end
 
     def self.mysql?
-      adapter_name.downcase == 'mysql2'
+      adapter_name.casecmp('mysql2').zero?
     end
 
     def self.postgresql?
-      adapter_name.downcase == 'postgresql'
+      adapter_name.casecmp('postgresql').zero?
     end
 
     def self.version
diff --git a/lib/gitlab/markup_helper.rb b/lib/gitlab/markup_helper.rb
index a5f767b134d..dda371e6554 100644
--- a/lib/gitlab/markup_helper.rb
+++ b/lib/gitlab/markup_helper.rb
@@ -40,7 +40,7 @@ module Gitlab
     # Returns boolean
     def plain?(filename)
       filename.downcase.end_with?('.txt') ||
-        filename.downcase == 'readme'
+        filename.casecmp('readme').zero?
     end
 
     def previewable?(filename)