ruby - How can I validate exits and aborts in RSpec?

Question

I am trying to spec behaviors for command line arguments my script receives to ensure that all validation passes. Some of my command line arguments will result in abort or exit being invoked because the parameters supplied are missing or incorrect.

I am trying something like this which isn't working:

# something_spec.rb
require 'something'
describe Something do
    before do
        Kernel.stub!(:exit)
    end

    it "should exit cleanly when -h is used" do
        s = Something.new
        Kernel.should_receive(:exit)
        s.process_arguments(["-h"])
    end
end

The exit method is firing cleanly preventing RSpec from validating the test (I get "SystemExit: exit").

I have also tried to mock(Kernel) but that too is not working as I'd like (I don't see any discernible difference, but that's likely because I'm not sure how exactly to mock Kernel and make sure the mocked Kernel is used in my Something class).

Answer 1

try this:

module MyGem
  describe "CLI" do
    context "execute" do

      it "should exit cleanly when -h is used" do
        argv=["-h"]
        out = StringIO.new
        lambda { ::MyGem::CLI.execute( out, argv) }.should raise_error SystemExit
      end

    end
  end
end