Need to call asdf:load-system (or equivalent) from asdf:test-system

[Albus Matt Piroglu]

Thanks for the replies! A few clarifications and further questions:

I'm not entirely sure what you mean by "test" in the above. If you look
> at the tests in ASDF (in the test/ subdirectory), you will see that
> these are typically run from the shell, and so don't have any lasting
> effects.  Lisp starts, the test is run, lisp exits. So typically we
> don't have to worry about clearing systems.
>

Yes, when I wrote 'test', I was pointing to the test subfolder in asdf.
And as you described, the way those tests work is different than what I
wanted to achieve. I am currently calling (asdf:test-system "lib-helper")
to do my tests, and would like to continue using the same lisp image from
that point on. For reference, I uploaded related changes (with the
recursive load-op currently in the code) to my lib:
https://github.com/albuspiroglu/cl-lib-helper

The test of concern is:
https://github.com/albuspiroglu/cl-lib-helper/blob/f98f39dd1460287ddcb77525bde375ed29c8c360/test/lib-helper-test.lisp#L130
And the system this test loads is under its sub-folder test-system/ . I
just needed the simplest system definition with two symbols in a package.
Then the lib-helper will create some target packages and reference those
symbols in different ways, depending on whether the user has chosen to
pre-load, and map to their chosen set of systems.


> If you want to understand better how ASDF does its testing, a good
> resource is to read the file test/script-support.lisp which has the
> testing utilities. (If you would like to submit a merge request with
> additional comments and/or docstrings for this file, that would be
> welcome!)
>
When I read the code you mentioned, I'll make sure to do some improvements,
or at least attempt!


> You will see that this file contains a def-test-system macro
> (unfortunately, without a docstring) that can be used in tests to create
> a system without needing an asd file.  See, for example,
> test/test-sysdef-asdf.script for uses of def-test-system
>

I was looking for something like this yesterday, before creating a dummy
system under my test/ folder. Then I realised it was convenient to create
the asd file and a lisp file along so that I can define a test package
along with the system, because my cl-lib-helper checks for some symbols in
a package which is expected to be asdf-loaded.


> This file also has an example of the use of CLEAR-SYSTEM, which is
> exported by ASDF and is defined as follows:
>
> >     "Clear the entry for a SYSTEM in the database of systems
> > previously defined. However if the system was registered as PRELOADED
> > (which it is if it is IMMUTABLE), then a new system with the same name
> > will be defined and registered in its place from which build details
> > will have been cleared.
> > Note that this does NOT in any way cause any of the code of the system
> > to be unloaded.
> > Returns T if system was or is now undefined, NIL if a new preloaded
> > system was redefined."
>
> Note from the above that you cannot unload a system.  Loading a system
> has arbitrary effects on the running lisp image, and those effects
> cannot, in general, be undone.  This is part of the reason that each
> ASDF test is run in a separate lisp process.
>
I always thought it's a matter of what the library's code brings to the
lisp image that creates this complication, thus I started putting some
library cleanup functions to help with reloading my libs without restarting
lisp. What I do is, generally, delete the packages of the library and then
call asdf:clear-system. Maybe do any other generic method / class
definition deletion as required, which I haven't needed yet. For example
this function from the same library I mentioned does exactly that:
https://github.com/albuspiroglu/cl-lib-helper/blob/f98f39dd1460287ddcb77525bde375ed29c8c360/packages-common.lisp#L5

I wonder if there are other side-effects that asdf itself creates which
would be more difficult to clean up?


>
> As for testing whether or not a system has been loaded, typically what
> is done is to define a package and a variable in that package in the
> test system, and then check for that variable having the expected value
> in order to see if the system has been loaded.
>
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