Re: Best practice for mocking functions/prompts/etc.

[Nic Ferrier <nferrier@ferrier.me.uk>]

Jorgen Schaefer <forcer@forcix.cx> writes:

> (defun the-function ()
>   (read-file-name "Foo: "))
>
>
> (ert-deftest the-function ()
>   ;; Describe the-function
>
>   ;; It should prompt the user for a file name.
>   (cl-letf* ((called-prompt nil)
>              (test-file "/test-file")
>              ((symbol-function 'read-file-name)
>               (lambda (prompt)
>                 (setq called-prompt prompt)
>                 test-file)))
>
>     (let ((returned-file (the-function)))
>
>       (should (equal returned-file test-file))
>       (should (equal called-prompt "Foo: ")))))
>
>
> Is there a better way? Especially one that makes it easier to check if
> the function was called at all and with what arguments, as opposed to
> carrying around 1-2 extra variables per mocked function?

I don't see any reason to test all those things for every interactive
function. I think interactive working (or not) should be tested once, by
some tests around interactive. You don't have to test that.

In this example, you should just mock read-file-name. Which you're
doing.

Using cl-letf, cl-labels, cl-flet or noflet would all be ok I think.


There are elisp mocking libs. But with lisp you don't really need them.


Nic