Fix pytest collection errors from trailing comma in parametrize argnames#7450
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pytest 9.1.0 (released 2026-06-13) shipped pytest-dev/pytest#14125, which fixes pytest-dev/pytest#719: a trailing comma in a string argnames value (e.g. "args, " or "config_file_name,") now behaves like the tuple form ("arg",) and unpacks each value as a tuple. Before 9.1.0 the trailing comma was discarded and the value was passed as-is for the single argname, so these tests passed by accident. After the change pytest unpacks each value, and our non-tuple values no longer match the single argname, failing collection: - "args, " + value {} -> names (1) != values (0) - "config_file_name," + "config.yaml" -> names (1) != values (11) (the string is unpacked into its 11 characters) These tests date back to 2021 and were unchanged; tox does not pin pytest, so CI picked up 9.1.0 two days after its release and exposed the latent issue. Fix: drop the trailing comma so each value is treated as a single argument on every pytest version. Refs: pytest-dev/pytest#14125 pytest-dev/pytest#719 pytest 9.1.0 changelog: https://docs.pytest.org/en/stable/changelog.html
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Description of changes
Root cause: pytest 9.1.0 (released 2026-06-13) shipped #14125 (pytest-dev/pytest#14125) / #719 (pytest-dev/pytest#719), which makes a trailing comma in string argnames ("arg,") behave like the tuple form ("arg",) and unpack each value as a tuple. Our 2021-era tests used "args, " / "config_file_name," with
▎ non-tuple values, so values now unpack to the wrong arity ({}→0, "config.yaml"→11 chars) and collection fails. tox doesn't pin pytest, so CI picked up 9.1.0 two days after its release. Fix: drop the trailing comma.
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