Consistent parse exceptions

[davila-vilanova]

Description

Addresses issue https://github.com/ariebovenberg/whenever/issues/94.

Summary of changes

• Removed InvalidFormat error type, always raise ValueError when parsing fails.
• Included offending string in error messages.
• When available, chained the exception that caused the parsing the fail.
• Updated tests to:
  • verify that ValueError is raised,
  • ensure the error message matches expectation,
  • where appropriate (e.g. when it adds information about a specific reason) verify the type and message of the chained exception.
• Updated docs to reflect all parsing errors are now ValueErrors.

Checklist

• [x] Build runs successfully
• [x] Docs updated

[ariebovenberg]

Thanks @davila-vilanova for your PR, I'll have a look shortly.

Could you rebase your branch though?

[ariebovenberg]

Looks like a test coverage gap appeared. You can find it with pytest --cov=whenever --cov-report html and opening htmlcov/index.html

[davila-vilanova]

Branch rebased.

The coverage gap came from two raise statements that were not supposed to ever execute within the then current possible codepaths but were there in case the happy path condition got out of sync with the individual error checks under it, as a kind of insurance.

They are no longer necessary as I've removed the individual error checks -- coverage is back to 100%.

[ariebovenberg]

🙏 thanks for your contribution! It may be a while before this rolls out in a release though, since it's technically a backwards incompatible change (an exception was removed) and I'd like to bundle it with others if possible.

[davila-vilanova]

🙏 thanks for your contribution!

Thank you!

it's technically a backwards incompatible change (an exception was removed) and I'd like to bundle it with others if possible.

Makes sense.