Simple method to assert something

assert.rb

module Assert
  class AssertFailedException < Exception
  end
  
  def assert!(object, method, expected_value)
    # If method returns a boolean and expected value is nil, assume that
    # truthy passes the assertion
    result = object.send(method)
    if result != expected_value
      raise new Assert::AssertFailedException("#{object} expected #{method} to be #{expected_value} but was #{result}"
    end
  end
end

Object.send(:include, Assert)