Stubbing terminal user input in RSpec

Reading user input in console applications is usually done using Kernel#gets. Stubbing that can be a bit hairy.

When your code expects user input, you can not say Kernel.stub(gets: 'user input'). This will have no effect because of reasons.

Instead, you need to know which class will call gets. For example:

described_class.any_instance.stub(gets: 'user input')

If you do not know where gets is called, you can try something like this:

Object.any_instance.stub(gets: 'user input')

Any instance of an object should eventually hit that stub.