Add selected state for diff view in commit page

app/helpers/diff_helper.rb

@@ -232,7 +232,7 @@ module DiffHelper
     # Always use HTML to handle case where JSON diff rendered this button
     params_copy.delete(:format)
 
-    link_to url_for(params_copy), id: "#{name}-diff-btn", class: (selected ? 'btn gl-button active' : 'btn gl-button'), data: { view_type: name } do
+    link_to url_for(params_copy), id: "#{name}-diff-btn", class: (selected ? 'btn gl-button btn-default selected' : 'btn gl-button btn-default'), data: { view_type: name } do
       title
     end
   end

changelogs/unreleased/selected-state-commit-view.yml

+---
+title: Add selected state for diff view in commit page
+merge_request: 54762
+author: Yogi (@yo)
+type: changed

spec/features/merge_request/user_selects_branches_for_new_mr_spec.rb

@@ -121,14 +121,14 @@ RSpec.describe 'Merge request > User selects branches for new MR', :js do
 
     click_link 'Changes'
 
-    expect(page).to have_css('a.btn.active', text: 'Inline')
-    expect(page).not_to have_css('a.btn.active', text: 'Side-by-side')
+    expect(page).to have_css('a.btn.selected', text: 'Inline')
+    expect(page).not_to have_css('a.btn.selected', text: 'Side-by-side')
 
     click_link 'Side-by-side'
 
     within '.merge-request' do
-      expect(page).not_to have_css('a.btn.active', text: 'Inline')
-      expect(page).to have_css('a.btn.active', text: 'Side-by-side')
+      expect(page).not_to have_css('a.btn.selected', text: 'Inline')
+      expect(page).to have_css('a.btn.selected', text: 'Side-by-side')
     end
   end