How to reload a ruby class

Question

In many of our classes we cache expensive operation for performance. e.g.

def self.foo
    @foo ||= get_foo
end 

This works great in the application, however the tests (RSpec) fail because of these memoized variables. The values from the first test are being returned in the subsequent tests, when we expect fresh values.

So the question is: how do I reload the class? Or remove all the memoized variables?

Answer 1

Add an after (or before) block to the example group to remove the instance variable (assuming the object in question is the subject):

after do
  subject.instance_variable_set(:@foo, nil)
end

Or fix the problem. Having a memoized class instance variable is a bit of a smell since it will never change. Normal instance variables wouldn't have this issue since you'd create a new object for each test.

Answer 2

Build your classes and tests in such a way that the cached data remains correct or gets deleted when it is invalid. Consider adding a method to clear the cache and calling it in a rspec before block.