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Re: testing macros and fixtures
From: |
Phillip Lord |
Subject: |
Re: testing macros and fixtures |
Date: |
Tue, 13 Oct 2015 12:34:49 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Artur Malabarba <address@hidden> writes:
> 2015-10-12 22:13 GMT+01:00 Phillip Lord
>
>> ERT is quite nice, but one of the things that I have found lacking is a
>> nice set of predicates, for use within should.
>>
>> So, when I wrote test for my "lentic" package I needed some functions
>> like, so that I could do things like:
>>
>> (should
>> (test-eq-after-this
>> "blah-before.txt"
>> "blah-after.txt"
>> (insert "hello")))
>>
>> which opens "blah-before.txt" runs (insert "hello") then compares the
>> result with "blah-after.txt".
>
> I think that's a pretty specific use-case. So it's best to let people write
> their own macros for this.
>
> (defmacro should-eq-after-body (file-before file-after &rest body)
> `(let ((bef
> (with-temp-buffer
> (insert-file-contents file-before)
> ,@body
> (buffer-string))))
> (should (string= bef (with-temp-buffer
> (insert-file-contents file-after)
> (buffer-string))))))
I'd imagine it's pretty common -- assuming that (insert "hello") is
anything at all of course.
>> My version of this also does a diff of the
>> results if the two are not equal.
>
> This certainly seems very useful. Maybe ert should do this on *all*
> multi-line string comparisons instead of doing its default
> “different-strings” report (which, most of the time, just says “strings are
> of different length”).
Yep. I use a function to replace "string=" that looks like this.
(defun lentic-test-equal-loudly (a b)
"Actually, this just tests equality and shouts if not."
;; change this to t to disable noisy printout
(if lentic-test-quiet
(string= a b)
(if (string= a b)
t
(message "Results:\n%s\n:Complete\nShouldbe:\n%s\nComplete:"
cloned-results cloned-file)
(let* ((a-buffer
(generate-new-buffer "a"))
(b-buffer
(generate-new-buffer "b"))
(a-file
(make-temp-file
(buffer-name a-buffer)))
(b-file
(make-temp-file
(buffer-name b-buffer))))
(with-current-buffer
a-buffer
(insert a)
(write-file a-file))
(with-current-buffer
b-buffer
(insert b)
(write-file b-file))
(message "diff:%senddiff:"
(with-temp-buffer
(call-process
"diff"
nil
(current-buffer)
nil
"-c"
a-file
b-file)
(buffer-string))))
nil)))
An egregious hack, of course, but it was quick and does what I need.
> Yes, there are many packages that use custom-deisgned temp-buffers for
> testing. In fact, most non-trivial packages do. I'd really like to see ert
> offer a common interface for this. The difficulty for that is that each
> package has very different needs when it comes to testing in buffers, so I
> have no idea what this common interface could be.
I think I'll put this next into my todo list. Maintaining the current
(dreadful) infrastructure that I have for lentic is painful to say the
least, and I think a lot of this should be reusuable.
As you say, there are lots of examples.
Phil