```ruby
require 'rails_helper'

Thread.abort_on_exception = true

RSpec.describe PaymentGateway, type: :service do
  describe '.available?' do
    around(:example) do |example|
      pdq_stub
      subject.run
      WebMock.after_request { example.run }
      subject.stop
      WebMock.reset_callbacks
    end

    context 'when the gateway returns HTTP error codes' do
      let(:pdq_stub) do
        stub_request(:get, ENV.fetch('PAYMENT_GATEWAY_PING_ENDPOINT')).to_return status: 500, body: ''
      end

      it 'returns false' do
        expect(subject.available?).to be false
      end
    end

    context 'when the gateway is down' do
      let(:pdq_stub) do
        stub_request(:get, ENV.fetch('PAYMENT_GATEWAY_PING_ENDPOINT')).to_raise(Errno::ECONNREFUSED)
      end

      it 'returns false' do
        expect(subject.available?).to be false
      end
    end

    context 'when the gateway is up' do
      let(:pdq_stub) do
        stub_request(:get, ENV.fetch('PAYMENT_GATEWAY_PING_ENDPOINT')).to_return status: 200, body: ''
      end

      it 'returns true' do
        expect(subject.available?).to be true
      end
    end
  end
end
```

Add sleep to allow threrad to start up - we were getting flickering tests
user
```ruby
require 'rails_helper'

Thread.abort_on_exception = true

RSpec.describe PaymentGateway, type: :service do
  describe '.available?' do
    around(:example) do |example|
      pdq_stub
      subject.run
      sleep 1 # Allow thread to start - we were getting flickering failures
      example.run
      subject.stop
      WebMock.reset_callbacks
    end

    context 'when the gateway returns HTTP error codes' do
      let(:pdq_stub) do
        stub_request(:get, ENV.fetch('PAYMENT_GATEWAY_PING_ENDPOINT')).to_return status: 500, body: ''
      end

      it 'returns false' do
        expect(subject.available?).to be false
      end
    end

    context 'when the gateway is down' do
      let(:pdq_stub) do
        stub_request(:get, ENV.fetch('PAYMENT_GATEWAY_PING_ENDPOINT')).to_raise(Errno::ECONNREFUSED)
      end

      it 'returns false' do
        expect(subject.available?).to be false
      end
    end

    context 'when the gateway is up' do
      let(:pdq_stub) do
        stub_request(:get, ENV.fetch('PAYMENT_GATEWAY_PING_ENDPOINT')).to_return status: 200, body: ''
      end

      it 'returns true' do
        expect(subject.available?).to be true
      end
    end
  end
end
```
assistant