[bug#55845] [PATCH 1/1] ui: Improve pager selection logic when less is not installed.

[Taiju HIGASHI]

Maxime Devos <maximedevos@telenet.be> writes:

> Taiju HIGASHI schreef op do 09-06-2022 om 19:23 [+0900]:
>> Hi Maxime,
>>
>> I tried to mock open-pipe* and isatty?* using the mock macro and also
>> add a test to inspect the program coming across to open-pipe*, but gave
>> up because I could not get the return value of the
>> with-paginated-output-port macro.
>
> The return value of 'with-paginated-output-port' is just whatever the
> last expression put in that macro evaluates to.  Also 'close-pipe'
> needs to be mocked, otherwise an error will result.
>
> Try:
>
> (test-assert "with-paginated-output-port: finds less in PATH"
>   (call-with-temporary-directory
>     (lambda (dir)
>       (define used-command #false)
>       (with-environment-variables
>           `(("PATH" ,dir))
>         (make-dummy-executable-file dir "less")
>         (mock ((ice-9 popen) open-pipe*
>                (lambda (mode command . args)
>                  (when used-command ; <--- an extra test
>                     (error "open-pipe* should only be called once"))
>                  (set! used-command command) ; <--- this captures the passed 
> command
>                  (%make-void-port ""))) ; return a dummy port
>               (mock ((ice-9 popen) close-pipe (const 'ok))
>                  (mock ((guix colors) isatty?* (const #t))
>                     (with-paginated-output-port port 'ok)))))
>       (and (pk 'used-command used-command dir) ; <-- fails on my computer 
> because a non-absolute path is passed and I haven't applied our patch
>            (string=? (in-vicinity dir "less") used-command)))))

Thank you very much! It worked as expected!

I made a v3 patch.

v3-0001-ui-Improve-pager-selection-logic-when-less-is-not.patch
Description: v3 patch

Two tests have been added: one to select pager from the environment
variable and the other to select less from the PATH.

I also made some improvements to the existing tests based on your
answers.

There are many ways to do this. I learned a lot.

Thanks,
-- 
Taiju