Test exit! with RSpec

Question

How can I test with RSpec some code with #exit!?

def method
  ...
rescue MyError => e
  logger.error "FATAL ERROR"
  exit! 1
end

I can test this code with #exit method because raise the SystemExit exception.

it "logs a fatal error" do
  lambda do
    object.method
    expect(logger).to have_received(:error).with("FATAL ERROR")
  end
end

it "exits" do
  expect { object.method }.to raise_error(SystemExit)
end

I'm not sure if I can achieve something similar. I'm thinking to reimplement the exit! method in Kernel module, just only for the specs. Any ideas?

Answer 1

You can stub the exit! method for the object:

it "logs a fatal error" do
  lambda do
    allow(object).to receive(:exit!)
    object.method
    expect(logger).to have_received(:error).with("FATAL ERROR")
  end
end

it "exits" do
  expect(object).to receive(:exit!)

  object.method
end