Add feature flag and specs

Cover `Bridge::Common` with tests
and additional feature flag

config/feature_flags/development/ci_bridge_pipeline_details.yml

+---
+name: ci_bridge_pipeline_details
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/41263
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/250683
+group: group::memory
+type: development
+default_enabled: true

lib/gitlab/ci/status/bridge/common.rb

@@ -10,19 +10,29 @@ module Gitlab
           end
 
           def has_details?
-            can?(user, :read_pipeline, subject.downstream_pipeline)
+            !!details_path
           end
 
           def details_path
-            return unless subject.downstream_pipeline
+            return unless Feature.enabled?(:ci_bridge_pipeline_details, subject.project, default_enabled: true)
+            return unless can?(user, :read_pipeline, downstream_pipeline)
 
-            pipeline = subject.downstream_pipeline
-            project_pipeline_path(pipeline.project, pipeline)
+            project_pipeline_path(downstream_project, downstream_pipeline)
           end
 
           def has_action?
             false
           end
+
+          private
+
+          def downstream_pipeline
+            subject.downstream_pipeline
+          end
+
+          def downstream_project
+            downstream_pipeline&.project
+          end
         end
       end
     end

spec/lib/gitlab/ci/status/bridge/common_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Ci::Status::Bridge::Common do
+  let_it_be(:user) { create(:user) }
+  let_it_be(:bridge) { create(:ci_bridge) }
+  let_it_be(:downstream_pipeline) { create(:ci_pipeline) }
+
+  before_all do
+    create(:ci_sources_pipeline,
+      source_pipeline: bridge.pipeline,
+      source_project: bridge.pipeline.project,
+      source_job: bridge,
+      pipeline: downstream_pipeline,
+      project: downstream_pipeline.project)
+  end
+
+  subject do
+    Gitlab::Ci::Status::Core
+      .new(bridge, user)
+      .extend(described_class)
+  end
+
+  describe '#details_path' do
+    context 'when user has access to read downstream pipeline' do
+      before do
+        downstream_pipeline.project.add_developer(user)
+      end
+
+      it { expect(subject).to have_details }
+      it { expect(subject.details_path).to include "pipelines/#{downstream_pipeline.id}" }
+
+      context 'when ci_bridge_pipeline_details is disabled' do
+        before do
+          stub_feature_flags(ci_bridge_pipeline_details: false)
+        end
+
+        it { expect(subject).not_to have_details }
+        it { expect(subject.details_path).to be_nil }
+      end
+    end
+
+    context 'when user does not have access to read downstream pipeline' do
+      it { expect(subject).not_to have_details }
+      it { expect(subject.details_path).to be_nil }
+    end
+  end
+end