Fix bug when removed file was not appearing in merge request diff

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

CHANGELOG

@@ -17,6 +17,7 @@ v 8.1.0 (unreleased)
   - Move CI variables page to project settings area
   - Move CI triggers page to project settings area
   - Move CI project settings page to CE project settings area
+  - Fix bug when removed file was not appearing in merge request diff
 
 v 8.0.3
   - Fix URL shown in Slack notifications

app/helpers/diff_helper.rb

@@ -167,4 +167,23 @@ module DiffHelper
       content_tag(:span, commit_id, class: 'monospace'),
     ].join(' ').html_safe
   end
+
+  def commit_for_diff(diff)
+    if diff.deleted_file
+      @merge_request ? @merge_request.commits.last : @commit.parent_id
+    else
+      @commit
+    end
+  end
+
+  def diff_file_html_data(project, diff_commit, diff_file)
+    {
+      blob_diff_path: namespace_project_blob_diff_path(project.namespace, project,
+                                                       tree_join(diff_commit.id, diff_file.file_path))
+    }
+  end
+
+  def editable_diff?(diff)
+    !diff.deleted_file && @merge_request && @merge_request.source_project
+  end
 end

app/views/projects/diffs/_diffs.html.haml

@@ -15,7 +15,12 @@
 
 .files
   - diff_files.each_with_index do |diff_file, index|
-    = render 'projects/diffs/file', diff_file: diff_file, i: index, project: project
+    - diff_commit = commit_for_diff(diff_file.diff)
+    - blob = project.repository.blob_for_diff(diff_commit, diff_file.diff)
+    - next unless blob
+
+    = render 'projects/diffs/file', i: index, project: project,
+      diff_file: diff_file, diff_commit: diff_commit, blob: blob
 
 - if @diff_timeout
   .alert.alert-danger

app/views/projects/diffs/_file.html.haml

-- blob = project.repository.blob_for_diff(@commit, diff_file.diff)
-- return unless blob
-- blob_diff_path = namespace_project_blob_diff_path(project.namespace, project, tree_join(@commit.id, diff_file.file_path))
-.diff-file{id: "diff-#{i}", data: {blob_diff_path: blob_diff_path }}
+.diff-file{id: "diff-#{i}", data: diff_file_html_data(project, diff_commit, diff_file)}
   .diff-header{id: "file-path-#{hexdigest(diff_file.new_path || diff_file.old_path)}"}
-    - if diff_file.deleted_file
-      %span="#{diff_file.old_path} deleted"
-
-      .diff-btn-group
-        - if @commit.parent_ids.present?
-          = view_file_btn(@commit.parent_id, diff_file, project)
-    - elsif diff_file.diff.submodule?
+    - if diff_file.diff.submodule?
       %span
         - submodule_item = project.repository.blob_at(@commit.id, diff_file.file_path)
         = submodule_link(submodule_item, @commit.id, project.repository)
     - else
       %span
-        - if diff_file.renamed_file
+        - if diff_file.deleted_file
+          = "#{diff_file.old_path} deleted"
+        - elsif diff_file.renamed_file
           = "#{diff_file.old_path} renamed to #{diff_file.new_path}"
         - else
           = diff_file.new_path
+
         - if diff_file.mode_changed?
           %span.file-mode= "#{diff_file.diff.a_mode} → #{diff_file.diff.b_mode}"
 
@@ -28,12 +22,12 @@
             %i.fa.fa-comments
            
 
-        - if @merge_request && @merge_request.source_project
+        - if editable_diff?(diff_file)
           = edit_blob_link(@merge_request.source_project,
               @merge_request.source_branch, diff_file.new_path,
               after: ' ', from_merge_request_id: @merge_request.id)
 
-        = view_file_btn(@commit.id, diff_file, project)
+        = view_file_btn(diff_commit.id, diff_file, project)
 
   .diff-content.diff-wrap-lines
     -# Skipp all non non-supported blobs