Rspec Race Conditions

test_rspec.rb

describe 'Race condition POST /api/v1/transaction/electricity', vcr: { cassette_name: 'race_condition_transaction_electricity' } do
  it { expect(ActiveRecord::Base.connection.pool.size).to eq(5) }

  context 'send requests simultaneously' do
    let!(:user) { create(:user, limit_credit: 500_000, balance: 60_000) }

    it 'should create one transaction' do
      begin
        concurrency_level = 4
        fail_occurred = false
        wait_for_it = true

        threads = Array.new(concurrency_level) do |_i|
          Thread.new do
            true while wait_for_it
            begin
              post '/api/v1/transaction/electricity', params: transaction_params, headers: transaction_headers
              fail_occurred = (response.status == 422)
            end
          end
        end

        wait_for_it = false
        threads.each(&:join)

        user.reload

        # dari 4 percobaan transaksi terdapat 3 transaksi gagal
        expect(fail_occurred).to be(true)
        expect(user.balance.to_i).to eq(8_500)
        # transaksi yang tergenerate hanya 1 transaksi
        expect(Transaction.all.count).to eq(1)
      ensure
        ActiveRecord::Base.connection_pool.disconnect!
      end
    end
  end
end