Re: Contributing Guix Home services

[Tanguy LE CARROUR]

Hi Ludo’,

Sorry, busy week! 😅 … euh… busy 2 weeks! 😱


Quoting Ludovic Courtès (2023-05-03 22:42:27)
> Tanguy LE CARROUR <tanguy@bioneland.org> skribis:
> 
> > Quoting Ludovic Courtès (2023-04-17 15:39:02)
> >> Tanguy LE CARROUR <tanguy@bioneland.org> skribis:
> >> > It's been quite a journey on my side! Ups. Downs. Mostly downs, though! 😅
> >> > Thanks to Simon's unconditional technical and moral support, a **LOT**
> >> > has changed since I sent this message. Hopefully for the better! 🤞
> >> 
> >> Heh.  :-)  While it’s fresh on your mind, it would be nice to list the
> >> problems you ran into on your journey and see what we can do about it.
> >
> > Mostly figuring out how to test it!
> >
> > On my machine at home, `guix home reconfigure` can take minutes.
> 
> Did you test with ‘guix home container’ first?  That’s what I do and I
> added this command precisely so one can test without any risk of
> breaking things.
> 
> It’s still too slow though, that’s right.

Yes, when I use my actual home config, it also takes minutes to build
the container, but, if I use a fake home config, limited to the service
I want to test, it's way faster! Still slower than the following…

Append this test code at the end of the service file:

```scheme
(define configuration
  (home-service-configuration
   ; […]
  )

(mixed-text-file "test" (serialize-configuration configuration 
home-service-configuration-fields))
```

Then, from the command line:

```console
$ cat (guix build -f path/to/home/service.scm)
# … the content of the generated file
```


> > I can only test file generation, though.
> 
> The msmtp service does nothing but file generation though, right?
> 
> > Then I painfully discovered that replacing in a string is not as easy as
> > it sounds, or, more precisely, that "python replace in string" yields
> > better results than "scheme replace in string" in DuckDuckGo!
> 
> True!  Perhaps something to add to the Cookbook’s Scheme intro.
> 
> (Fun fact: I’ve never used that (ice-9 string-fun) module that keeps
> popping up in new code.  :-))

Whaaaat?! 🤯 How one would you do without it? 😅


-- 
Tanguy