tests: Spec tests shouldn't fetch remote git repositories. (#43656)

Currently, some of the tests in `spec_format` and `spec_semantics` fetch
the actual zlib repository when run, because they call `str()` on specs
like `zlib@foo/bar`, which at least currently requires a remote git clone
to resolve.

This doesn't change the behavior of git versions, but it uses our mock git
repo infrastructure and clones the `git-test` package instead of the *real*
URL from the mock `zlib` package.

This should speed up tests.  We could probably refactor more so that the git
tests *all* use such a fixture, but the `checks` field that unfortunately
tightly couples the mock git repository and the `git_fetch` tests complicates
this. We could also consider *not* making `str()` resolve git versions, but
I did not dig into that here.

- [x] add a mock_git_test_package fixture that sets up a mock git repo *and*
      monkeypatches the `git-test` package (like our git test packages do)
- [x] use fixture in `test_spec_format_path`
- [x] use fixture in `test_spec_format_path_posix`
- [x] use fixture in `test_spec_format_path_windows`
- [x] use fixture in `test_parse_single_spec`

0 files changed, 0 insertions, 0 deletions