Merge branch '297480-fix-sort-same-name' into 'master'

Fix diff sorting when 2 files have the same name

See merge request gitlab-org/gitlab!52202

lib/gitlab/diff/file_collection_sorter.rb

@@ -3,6 +3,10 @@
 module Gitlab
   module Diff
     class FileCollectionSorter
+      B_FOLLOWS_A = 1
+      A_FOLLOWS_B = -1
+      EQUIVALENT = 0
+
       attr_reader :diffs
 
       def initialize(diffs)
@@ -29,14 +33,16 @@ module Gitlab
         a_part = a_parts.shift
         b_part = b_parts.shift
 
-        return 1 if a_parts.size < b_parts.size && a_parts.empty?
-        return -1 if a_parts.size > b_parts.size && b_parts.empty?
+        return B_FOLLOWS_A if a_parts.size < b_parts.size && a_parts.empty?
+        return A_FOLLOWS_B if a_parts.size > b_parts.size && b_parts.empty?
 
         comparison = a_part <=> b_part
 
-        return comparison unless comparison == 0
+        return comparison unless comparison == EQUIVALENT
+        return compare_path_parts(a_parts, b_parts) if a_parts.any? && b_parts.any?
 
-        compare_path_parts(a_parts, b_parts)
+        # If A and B have the same name (e.g. symlink change), they are identical so return 0
+        EQUIVALENT
       end
     end
   end

spec/lib/gitlab/diff/file_collection_sorter_spec.rb

@@ -5,11 +5,14 @@ require 'spec_helper'
 RSpec.describe Gitlab::Diff::FileCollectionSorter do
   let(:diffs) do
     [
+      double(new_path: 'README', old_path: 'README'),
       double(new_path: '.dir/test', old_path: '.dir/test'),
       double(new_path: '', old_path: '.file'),
       double(new_path: '1-folder/A-file.ext', old_path: '1-folder/A-file.ext'),
+      double(new_path: '1-folder/README', old_path: '1-folder/README'),
       double(new_path: nil, old_path: '1-folder/M-file.ext'),
       double(new_path: '1-folder/Z-file.ext', old_path: '1-folder/Z-file.ext'),
+      double(new_path: '1-folder/README', old_path: '1-folder/README'),
       double(new_path: '', old_path: '1-folder/nested/A-file.ext'),
       double(new_path: '1-folder/nested/M-file.ext', old_path: '1-folder/nested/M-file.ext'),
       double(new_path: nil, old_path: '1-folder/nested/Z-file.ext'),
@@ -19,7 +22,8 @@ RSpec.describe Gitlab::Diff::FileCollectionSorter do
       double(new_path: nil, old_path: '2-folder/nested/A-file.ext'),
       double(new_path: 'A-file.ext', old_path: 'A-file.ext'),
       double(new_path: '', old_path: 'M-file.ext'),
-      double(new_path: 'Z-file.ext', old_path: 'Z-file.ext')
+      double(new_path: 'Z-file.ext', old_path: 'Z-file.ext'),
+      double(new_path: 'README', old_path: 'README')
     ]
   end
 
@@ -36,6 +40,8 @@ RSpec.describe Gitlab::Diff::FileCollectionSorter do
         '1-folder/nested/Z-file.ext',
         '1-folder/A-file.ext',
         '1-folder/M-file.ext',
+        '1-folder/README',
+        '1-folder/README',
         '1-folder/Z-file.ext',
         '2-folder/nested/A-file.ext',
         '2-folder/A-file.ext',
@@ -44,6 +50,8 @@ RSpec.describe Gitlab::Diff::FileCollectionSorter do
         '.file',
         'A-file.ext',
         'M-file.ext',
+        'README',
+        'README',
         'Z-file.ext'
       ])
     end