Re: fix/ert-multiline-explanation

[Phillip Lord]

Eli Zaretskii <address@hidden> writes:

>> From: address@hidden (Phillip Lord)
>> Date: Wed, 21 Oct 2015 21:43:14 +0100
>> 
>> 
>> I would appreciate feedback on whether the change on
>> fix/ert-multiline-explanation would be a good one.
>> 
>> At the moment, ert allows you to attach explanation functions to explain
>> why tests have failed. Unfortunately, these explanations are printed out
>> using "pp" which escapes new lines. So multiline explanations are,
>> largely, unreadable.
>> 
>> So this patch ignores the value of pp-escape-newlines and resets it to
>> nil for the duration.
>
> Could you please show an example, with and without the changes?


Sure. The following code achieves the same thing with advice.

(defun silly-predicate (x))

(defun silly-explainer (&rest args)
  (message "Silly predicate is silly.
I mean, it's in the name, so why are you using it?
It's never going to return a sensible answer.
It is after silly.
            ^^^^^"))

(put 'silly-predicate
     'ert-explainer
     'silly-explainer)

(defun sisyphus--ert-pp-with-indentation-and-newline (orig object)
  (let ((pp-escape-newlines nil))
    (funcall orig object)))

(ert-deftest with ()
  (should
   (silly-predicate
    (advice-add
     'ert--pp-with-indentation-and-newline
     :around
     #'sisyphus--ert-pp-with-indentation-and-newline))))

(ert-deftest without ()
  (should
   (silly-predicate
    (advice-remove
     'ert--pp-with-indentation-and-newline
     #'sisyphus--ert-pp-with-indentation-and-newline))))


And the output.



F with
    (ert-test-failed
     ((should
       (silly-predicate
        (advice-add 'ert--pp-with-indentation-and-newline :around 
#'sisyphus--ert-pp-with-indentation-and-newline)))
      :form
      (silly-predicate nil)
      :value nil :explanation "Silly predicate is silly.
I mean, it's in the name, so why are you using it?
It's never going to return a sensible answer.
It is after silly.
            ^^^^^"))

F without
    (ert-test-failed
     ((should
       (silly-predicate
        (advice-remove 'ert--pp-with-indentation-and-newline 
#'sisyphus--ert-pp-with-indentation-and-newline)))
      :form
      (silly-predicate nil)
      :value nil :explanation "Silly predicate is silly.\nI mean, it's in the 
name, so why are you using it?\nIt's never going to return a sensible 
answer.\nIt is after silly.\n            ^^^^^"))



The point is with the advice I can use multiline explainers, without it
I can but it's pointless.

The bug fix is not essential -- as I have shown I can advice around it,
for this use case, I am struggling to see a use case for which "\n" is
better than a newline.

Phil