Both the old and new approaches are deeply unsatisfying to me, but
without reworking how these test commands are run, I think this is
about as close as we can get to enforcing that this specific call
raises ValueError.

The ability to handle files was originally added and documented based on
a misunderstanding of what the `license` field should include. The field
should be the name of the license, not the full text.

It is likely that anyone actually using this was outputing malformed
PKG-INFO files, because most license files contain newlines.

See GH issue #1551

This tests that `setup.py` is included by default in the distribution
with the egg_info command and when an sdist is built with
build_meta.build_sdist

These are tests to ensure that the specified deprecation warnings are
raised when the functions are called.

Co-authored-by: Junhan Huang <robin.j.huang@gmail.com>
Co-authored-by: Marton Pono <marci93@gmail.com>

Touch 'egg-info' directory

Ensure version is tagged only once.

'tox' determines whether a package should be rebuilt by comparing the
timestamp of the package's 'egg-info' directory and its 'setup.py' or
'setup.cfg' files [1][2]. Unfortunately this checks the 'egg-info'
directory itself, which is not updated, unlike the contents of that
directory. This means that 'tox' will always rebuild the package once
one of the two setup files has been updated.

While this is clearly a bug in 'tox' that should be fixed separately,
there is merit in using this as a heuristic so enable it.

[1] https://github.com/tox-dev/tox/blob/3.1.0/src/tox/venv.py#L253-L257
[2] https://github.com/tox-dev/tox/blob/3.1.0/src/tox/venv.py#L221-L244

Signed-off-by: Stephen Finucane <stephen@that.guru>