Use project CI config path to show CI blob viewer

When we check for a project's gitlab_ci_yml,
we always assume it uses `.gitlab-ci.yml`. However, project has its
own custom path for this.

In this commit, we are fixing this for blob viewer.

Changelog: fixed

app/models/blob_viewer/gitlab_ci_yml.rb

@@ -7,9 +7,14 @@ class GitlabCiYml < Base
 
     self.partial_name = 'gitlab_ci_yml'
     self.loading_partial_name = 'gitlab_ci_yml_loading'
-    self.file_types = %i[gitlab_ci]
     self.binary = false
 
+    # rubocop:disable Lint/UnusedMethodArgument -- The keyword argument is required by the parent class but not here.
+    def self.can_render?(blob, verify_binary: true)
+      blob.path == blob.project.ci_config_path_or_default
+    end
+    # rubocop:enable Lint/UnusedMethodArgument
+
     def validation_message(opts)
       return @validation_message if defined?(@validation_message)
 

spec/models/blob_spec.rb

@@ -387,6 +387,36 @@
         expect(blob.auxiliary_viewer).to be_a(BlobViewer::License)
       end
     end
+
+    context 'when the blob is GitlabCiYml' do
+      it 'returns a matching viewer for .gitlab-ci.yml' do
+        blob = fake_blob(path: '.gitlab-ci.yml')
+
+        expect(blob.auxiliary_viewer).to be_a(BlobViewer::GitlabCiYml)
+      end
+
+      it 'returns nil for non .gitlab-ci.yml' do
+        blob = fake_blob(path: 'custom-ci.yml')
+
+        expect(blob.auxiliary_viewer).to be_nil
+      end
+
+      context 'when the project has a custom CI config path' do
+        let(:project) { build(:project, ci_config_path: 'custom-ci.yml') }
+
+        it 'returns a matching viewer for the custom CI file' do
+          blob = fake_blob(path: 'custom-ci.yml')
+
+          expect(blob.auxiliary_viewer).to be_a(BlobViewer::GitlabCiYml)
+        end
+
+        it 'returns nil for the incorrect CI file' do
+          blob = fake_blob(path: '.gitlab-ci.yml')
+
+          expect(blob.auxiliary_viewer).to be_nil
+        end
+      end
+    end
   end
 
   describe '#rendered_as_text?' do