Invalid escape sequence warnings while running the test suite

[mgorny]

When running the test suite via pytest, I've noticed a bunch of warnings about invalid escape sequences:

========================================================== warnings summary ===========================================================
tests/dialects/test_bigquery.py:252
  /tmp/sqlglot/tests/dialects/test_bigquery.py:252: DeprecationWarning: invalid escape sequence '\y'
    "bigquery": "'x\\\y'",

tests/dialects/test_hive.py:723
  /tmp/sqlglot/tests/dialects/test_hive.py:723: DeprecationWarning: invalid escape sequence '\z'
    self.validate_identity("'\z'")

tests/dialects/test_hive.py:725
  /tmp/sqlglot/tests/dialects/test_hive.py:725: DeprecationWarning: invalid escape sequence '\z'
    self.validate_identity("'\\\z'")

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html

Note that Python outputs these when compiling .py into .pyc, so you need to remove existing .pyc files in order for them to be produced. The usual solution to these is to use raw strings (i.e. r"") but to be honest, I'm completely confused by the escape sequences there.

Fully reproducible code snippet

git clean -dfx
python3.11 -m pytest tests/dialects/

Official Documentation
n/a

[tobymao]

we don’t use pytest, does this repro on unittest?

[mgorny]

Yes.

$ python -m unittest discover -s tests/dialects/
/tmp/sqlglot/tests/dialects/test_bigquery.py:252: SyntaxWarning: invalid escape sequence '\y'
  "bigquery": "'x\\\y'",
Unable to set __version__, run `pip install -e .` or `python setup.py develop` first.
/tmp/sqlglot/tests/dialects/test_hive.py:723: SyntaxWarning: invalid escape sequence '\z'
  self.validate_identity("'\z'")
/tmp/sqlglot/tests/dialects/test_hive.py:725: SyntaxWarning: invalid escape sequence '\z'
  self.validate_identity("'\\\z'")
...................................................................................................................................................................................................................
----------------------------------------------------------------------
Ran 211 tests in 0.931s

OK

[tobymao]

i couldn't reproduce it, but i modified those tests