Effective Testing with RSpec 3

Block Matchers

With all the expectations we’ve seen so far, we’ve passed regular Ruby objects into expect:

11-matchers-included-in-rspec-expectations/03/block_matchers.rb

expect(3).to eq(3)

This is fine for checking properties of your data. But sometimes you need to check properties of a piece of code. For example, perhaps a certain piece of code is supposed to raise an exception. In this case, you can pass a block into expect:

11-matchers-included-in-rspec-expectations/03/block_matchers.rb

expect { raise 'boom' }.to raise_error('boom')

RSpec will run the block and watch for the specific side effects you specify: exceptions, mutating variables, I/O, and so on.

Raising and Throwing

You’re likely familiar with raising Ruby exceptions ...