Fix diff commenting results just after changing view

app/helpers/diff_helper.rb

@@ -15,7 +15,7 @@ module DiffHelper
   def diff_view
     @diff_view ||= begin
       diff_views = %w(inline parallel)
-      diff_view = cookies[:diff_view]
+      diff_view = params[:view] || cookies[:diff_view]
       diff_view = diff_views.first unless diff_views.include?(diff_view)
       diff_view.to_sym
     end

changelogs/unreleased/35695-comment-appears-in-a-wrong-place-after-changing-diff-view-to-inline.yml

+---
+title: Fix display of new diff comments after changing b between diff views
+merge_request:
+author:

spec/helpers/diff_helper_spec.rb

@@ -12,19 +12,32 @@ describe DiffHelper do
   let(:diff_file) { Gitlab::Diff::File.new(diff, diff_refs: diff_refs, repository: repository) }
 
   describe 'diff_view' do
+    it 'uses the view param over the cookie' do
+      controller.params[:view] = 'parallel'
+      helper.request.cookies[:diff_view] = 'inline'
+
+      expect(helper.diff_view).to eq :parallel
+    end
+
+    it 'returns the default value when the view param is invalid' do
+      controller.params[:view] = 'invalid'
+
+      expect(helper.diff_view).to eq :inline
+    end
+
     it 'returns a valid value when cookie is set' do
       helper.request.cookies[:diff_view] = 'parallel'
 
       expect(helper.diff_view).to eq :parallel
     end
 
-    it 'returns a default value when cookie is invalid' do
+    it 'returns the default value when cookie is invalid' do
       helper.request.cookies[:diff_view] = 'invalid'
 
       expect(helper.diff_view).to eq :inline
     end
 
-    it 'returns a default value when cookie is nil' do
+    it 'returns the default value when cookie is nil' do
       expect(helper.request.cookies).to be_empty
 
       expect(helper.diff_view).to eq :inline