Ensure code search results link to searched ref

Code searches allow you to choose branch name or tag when searching for
code. Previously the blob search results were linking to the URL with
the SHA of the branch and not the actual branch name being searched.
This works OK in some cases but usually the user expecting to be linked
to `/master/` instead of `/<some-sha>/` and in particular it is
problematic because when you are loading a file in a specific SHA you
cannot click the edit button to edit that file you just loaded.

We fix this by using the param `repository_ref` when present and
defaulting to the `default_branch` when absent.

See more at https://gitlab.com/gitlab-org/gitlab/-/issues/254932

app/helpers/search_helper.rb

@@ -86,6 +86,11 @@ module SearchHelper
     }).html_safe
   end
 
+  def repository_ref(project)
+    # Always #to_s the repository_ref param in case the value is also a number
+    params[:repository_ref].to_s.presence || project.default_branch
+  end
+
   # Overridden in EE
   def search_blob_title(project, path)
     path

app/views/search/_results.html.haml

@@ -10,10 +10,9 @@
       - if @project
         - link_to_project = link_to(@project.full_name, @project, class: 'ml-md-1')
         - if @scope == 'blobs'
-          - repository_ref = params[:repository_ref].to_s.presence || @project.default_branch
           = s_("SearchCodeResults|in")
           .mx-md-1
-            = render partial: "shared/ref_switcher", locals: { ref: repository_ref, form_path: request.fullpath, field_name: 'repository_ref' }
+            = render partial: "shared/ref_switcher", locals: { ref: repository_ref(@project), form_path: request.fullpath, field_name: 'repository_ref' }
           = s_('SearchCodeResults|of %{link_to_project}').html_safe % { link_to_project: link_to_project }
         - else
           = _("in project %{link_to_project}").html_safe % { link_to_project: link_to_project }

app/views/search/results/_blob.html.haml

 - project = blob.project
 - return unless project
-- blob_link = project_blob_path(project, tree_join(blob.ref, blob.path))
+- blob_link = project_blob_path(project, tree_join(repository_ref(project), blob.path))
 
 = render partial: 'search/results/blob_data', locals: { blob: blob, project: project, path: blob.path, blob_link: blob_link }

changelogs/unreleased/254932-fix-search-results-blob-link-to-branch.yml

+---
+title: Ensure code search results link to searched ref
+merge_request: 43510
+author:
+type: fixed

spec/features/search/user_searches_for_code_spec.rb

@@ -21,6 +21,7 @@ RSpec.describe 'User searches for code' do
       expect(page).to have_selector('.results', text: 'application.js')
       expect(page).to have_selector('.file-content .code')
       expect(page).to have_selector("span.line[lang='javascript']")
+      expect(page).to have_link('application.js', href: /master\/files\/js\/application.js/)
     end
 
     context 'when on a project page', :js do

spec/helpers/search_helper_spec.rb

@@ -399,4 +399,25 @@ RSpec.describe SearchHelper do
       end
     end
   end
+
+  describe '#repository_ref' do
+    let_it_be(:project) { create(:project, :repository) }
+    let(:params) { { repository_ref: 'the-repository-ref-param' } }
+
+    subject { repository_ref(project) }
+
+    it { is_expected.to eq('the-repository-ref-param') }
+
+    context 'when the param :repository_ref is not set' do
+      let(:params) { { repository_ref: nil } }
+
+      it { is_expected.to eq(project.default_branch) }
+    end
+
+    context 'when the repository_ref param is a number' do
+      let(:params) { { repository_ref: 111111 } }
+
+      it { is_expected.to eq('111111') }
+    end
+  end
 end