Update index before fetching modified files (#409)

ggilder · web-flow · commit 246af64aa95c · 2020-12-23T00:02:11.000-08:00
According to the [git-diff-index docs][1], git commands like diff-index and diff-files typically don't look at the actual contents of files in the working tree. This means that these commands can be easily fooled by operations that don't change the content of a file such as deleting and recreating it, or even running `touch` on a file. The docs then say that one may update the index to make it be in sync with the actual contents of the working directory. The recommended command would seem to be `git update-index --refresh`, but in my testing, this caused "needs update" errors in some of the tests. So I've resorted to using `git status`, which is probably a slightly more heavyweight command, but does pass the tests. [1]: https://git-scm.com/docs/git-diff-index Signed-off-by: Gabriel Gilder <gabriel@gabrielgilder.com>
diff --git a/lib/git/lib.rb b/lib/git/lib.rb
@@ -1065,6 +1065,8 @@ def command(cmd, *opts, &block)
     # @param [Array] opts the diff options to be used
     # @return [Hash] the diff as Hash
     def diff_as_hash(diff_command, opts=[])
+      # update index before diffing to avoid spurious diffs
+      command('status')
       command_lines(diff_command, opts).inject({}) do |memo, line|
         info, file = line.split("\t")
         mode_src, mode_dest, sha_src, sha_dest, type = info.split
diff --git a/tests/units/test_status.rb b/tests/units/test_status.rb
@@ -97,4 +97,20 @@ def test_untracked_boolean
       assert(!git.status.untracked?('test_file_2'))
     end
   end
+
+  def test_changed_cache
+    in_temp_dir do |path|
+      git = Git.clone(@wdir, 'test_dot_files_status')
+
+      create_file('test_dot_files_status/test_file_1', 'hello')
+
+      git.add('test_file_1')
+      git.commit('message')
+
+      delete_file('test_dot_files_status/test_file_1')
+      create_file('test_dot_files_status/test_file_1', 'hello')
+
+      assert(!git.status.changed?('test_file_1'))
+    end
+  end
 end
