How do I test if something is called in a rescue block?

foo.rb

class FooClass
  def bar
    baz
  rescue StandardError => e
    qux
    raise
  end

  def baz
  end

  def qux
  end
end

foo_spec.rb

require_relative 'foo'

describe '#foo' do
  it 'calls qux during exception' do
    foo = FooClass.new
    foo.stub(:baz).and_raise(StandardError)
    foo.should_not_receive(:qux)
    lambda{foo.bar}.should raise_error
  end
end

output

# The test passes irrespective of if I have foo.should_receive(:qux) or foo.should_not_receive(:qux)

➜ rspec foo_spec.rb --format=documentation

#foo
  calls qux during exception

Finished in 0.00443 seconds
1 example, 0 failures

This is pretty sneaky!

RSpec uses exceptions to immediately raise an error when you call a method that's not expected. So when you call foo.qux within the rescue block, you're raising yet another exception: MockExpectationError. This bubbles up and satisfies the should raise_error, so the test passes.