Add timeline of public posts about a trending link to REST API (#30381)

spec/requests/api/v1/timelines/link_spec.rb

@@ -0,0 +1,131 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe 'Link' do
+  let(:user)    { Fabricate(:user) }
+  let(:scopes)  { 'read:statuses' }
+  let(:token)   { Fabricate(:accessible_access_token, resource_owner_id: user.id, scopes: scopes) }
+  let(:headers) { { 'Authorization' => "Bearer #{token.token}" } }
+
+  shared_examples 'a successful request to the link timeline' do
+    it 'returns the expected statuses successfully', :aggregate_failures do
+      subject
+
+      expect(response).to have_http_status(200)
+      expect(body_as_json.pluck(:id)).to match_array(expected_statuses.map { |status| status.id.to_s })
+    end
+  end
+
+  describe 'GET /api/v1/timelines/link' do
+    subject do
+      get '/api/v1/timelines/link', headers: headers, params: params
+    end
+
+    let(:url) { 'https://example.com/' }
+    let(:private_status) { Fabricate(:status, visibility: :private) }
+    let(:undiscoverable_status) { Fabricate(:status, account: Fabricate.build(:account, domain: nil, discoverable: false)) }
+    let(:local_status) { Fabricate(:status, account: Fabricate.build(:account, domain: nil, discoverable: true)) }
+    let(:remote_status) { Fabricate(:status, account: Fabricate.build(:account, domain: 'example.com', discoverable: true)) }
+    let(:params) { { url: url } }
+    let(:expected_statuses) { [local_status, remote_status] }
+    let(:preview_card) { Fabricate(:preview_card, url: url) }
+
+    before do
+      if preview_card.present?
+        preview_card.create_trend!(allowed: true)
+
+        [private_status, undiscoverable_status, remote_status, local_status].each do |status|
+          PreviewCardsStatus.create(status: status, preview_card: preview_card, url: url)
+        end
+      end
+    end
+
+    context 'when there is no preview card' do
+      let(:preview_card) { nil }
+
+      it 'returns http not found' do
+        subject
+
+        expect(response).to have_http_status(404)
+      end
+    end
+
+    context 'when preview card is not trending' do
+      before do
+        preview_card.trend.destroy!
+      end
+
+      it 'returns http not found' do
+        subject
+
+        expect(response).to have_http_status(404)
+      end
+    end
+
+    context 'when preview card is trending but not approved' do
+      before do
+        preview_card.trend.update(allowed: false)
+      end
+
+      it 'returns http not found' do
+        subject
+
+        expect(response).to have_http_status(404)
+      end
+    end
+
+    context 'when the instance does not allow public preview' do
+      before do
+        Form::AdminSettings.new(timeline_preview: false).save
+      end
+
+      context 'when the user is not authenticated' do
+        let(:headers) { {} }
+
+        it 'returns http unauthorized' do
+          subject
+
+          expect(response).to have_http_status(401)
+        end
+      end
+
+      context 'when the user is authenticated' do
+        it_behaves_like 'a successful request to the link timeline'
+      end
+    end
+
+    context 'when the instance allows public preview' do
+      context 'with an authorized user' do
+        it_behaves_like 'a successful request to the link timeline'
+      end
+
+      context 'with an anonymous user' do
+        let(:headers) { {} }
+
+        it_behaves_like 'a successful request to the link timeline'
+      end
+
+      context 'with limit param' do
+        let(:params) { { limit: 1, url: url } }
+
+        it 'returns only the requested number of statuses', :aggregate_failures do
+          subject
+
+          expect(response).to have_http_status(200)
+          expect(body_as_json.size).to eq(params[:limit])
+        end
+
+        it 'sets the correct pagination headers', :aggregate_failures do
+          subject
+
+          expect(response)
+            .to include_pagination_headers(
+              prev: api_v1_timelines_link_url(limit: params[:limit], url: url, min_id: local_status.id),
+              next: api_v1_timelines_link_url(limit: params[:limit], url: url, max_id: local_status.id)
+            )
+        end
+      end
+    end
+  end
+end