Asserting that a particular exception is thrown in Cucumber

Question

Scenario

I\'m writing a library (no Ruby on Rails) for which I\'d like to have very detailed Cucumber features. This especially includes describing erro

Answer 1

It is possible to raise an exception in a When block and then make assertions about it in the following Then blocks.

Using your example:

When /^I do something unwanted$/ do
  @result = -> { throw_an_exception! }
end

Then /^an "(.*)" should be thrown$/ do |error|
  expect{ @result.call }.to raise_error(error)
end

That example uses RSpec's matchers but the important part is the -> (Lambda); which allows the reference to the throw_an_exception! method to be passed around.

I hope that helps!