Testing number of successfully returned threads using rspec

Question

如何测试成功返回主线程的线程数等于在rspec中创建的线程数？

Answer 1

describe '#update_tokens' do
  it 'is threadsafe', db_strategy: :truncation do
    u = create(:user)
    thread_injected = false
    time = Time.now
    allow(Time).to receive(:now) do
      unless thread_injected
        thread_injected = true
        Thread.new { u.reload.update_tokens('c2', 't2') }.join
      end
      time
    end
    u.update_tokens('c1', 't1')
    expect(u.tokens['c1']).not_to be_nil
    expect(u.tokens['c2']).not_to be_nil
  end
end

Original: http://blog.paulrugelhiatt.com/rails/rspec/2015/09/28/testing-thread-safety-concurrency-in-rspec.html