Current test suite doesn't cover the subsecond formatting at
all and toml11 is quite finicky with that. We should at the very
least test its behavior to avoid silent breakages on updates.
(cherry picked from commit 7ed0229d1abd4414144c7af396842462ce6fc1eb)
Upstream-PR: https://github.com/NixOS/nix/pull/13741
Change-Id: I6a6a696433b168072d6ad2585dce8a3c10ccbc39
(cherry picked from commit b2e48aac5c)
I think it is bad for these reasons when `tests/` contains a mix of
functional and integration tests
- Concepts is harder to understand, the documentation makes a good
unit vs functional vs integration distinction, but when the
integration tests are just two subdirs within `tests/` this is not
clear.
- Source filtering in the `flake.nix` is more complex. We need to
filter out some of the dirs from `tests/`, rather than simply pick
the dirs we want and take all of them. This is a good sign the
structure of what we are trying to do is not matching the structure
of the files.
With this change we have a clean:
```shell-session
$ git show 'HEAD:tests'
tree HEAD:tests
functional/
installer/
nixos/
```
(cherry picked from commit 68c81c737571794f7246db53fb4774e94fcf4b7e)
