How to write expect {}.to raise_error when rspec's syntax is configured with only should

Question

I have this configuration on rspec:

config.expect_with :rspec do |c|
  c.syntax = :should
end

It makes the expect {}.to raise_error invalid, how could I write this error raising test with should syntax?

Answer 1

I would suggest to use this only if the most-recent RSpec expect { code() }.to raise_error syntax is not available to you:

lambda { foo( :bad_param ) }.should raise_error

or

lambda { foo( :bad_param ) }.should raise_error( ArgumentError )

Replacing foo( :bad_param ) with whatever Ruby code you wish to assert fails, and ArgumentError with whatever exception class you expect the failure to raise.

Answer 2

In tests where I could use the expect syntax, I prefer to define that test in its own describe block, put the test content (ie expect { <this_content> }) into a stabby lambda, stick it in a new subject, and refer to it in an it block, like so:

describe "some test that raises error" do
  let(:bad_statement) { something_that_raises_an_error }
  subject { -> { bad_statement } }
  it { should raise_error }
end

If you wanted, you could also just do away with the let statement altogether and put its content directly in the subject.