Fix oembed controller test

spec/controllers/api/oembed_controller_spec.rb

 require 'rails_helper'
 
-RSpec.describe Api::OembedController, type: :controller do
+RSpec.describe Api::OEmbedController, type: :controller do
+  let(:alice)  { Fabricate(:account, username: 'alice') }
+  let(:status) { Fabricate(:status, text: 'Hello world', account: alice) }
 
+  describe 'GET #show' do
+    before do
+      get :show, params: { url: account_stream_entry_url(alice, status.stream_entry) }, format: :json
+    end
+
+    it 'returns http success' do
+      expect(response).to have_http_status(:success)
+    end
+  end
 end