How to test if method gets called using MiniTest::Mock

Question

I would like to test if a method, in this case 'puts', gets called when I include the Foo module into a class and call 'bar'.

require 'minitest/autorun'

module Foo
  def bar
    puts 'bar'
  end
end

class FooTest < MiniTest::Unit::TestCase
  def setup
    @class = Class.new do
      extend Foo
    end
  end

  def test_if_bar_method_calls_puts
    mock = MiniTest::Mock.new
    mock.expect(:puts, nil, ['bar'])
    @class.bar
    assert mock.verify
  end
end

Answer 1

You could do something like this:

  def test_if_bar_method_calls_puts
    mock = MiniTest::Mock.new
    mock.expect(:puts, nil, ['bar'])
    @class.stub :puts, -> (arg) { mock.puts arg } do
      @class.bar
    end
    assert mock.verify
  end