Add variables argument to the DatacubeExtension apply method

[itcarroll]

Related Issue(s):

• Fixes DatacubeExtension.apply is unaware of variables #781
• Helps with Tests and documentation for Datacube extension #324

Description:

An optional argument is added to the DatacubeExtension.apply method called variables and handed off to the variable setter. The argument is optional because Variable Objects are optional in the datacube extension spec.

A new test_apply_variables method for the DatacubeTest class does a round-trip check on a variable present in the example item using apply.

PR Checklist:

• Code is formatted (run pre-commit run --all-files)
• Tests pass (run scripts/test)
• Documentation has been updated to reflect changes, if applicable
• This PR maintains or improves overall codebase code coverage.
• Changes are added to the CHANGELOG. See the docs for information about adding to the changelog.

[itcarroll]

I don't have a lot of experience with type hints, so I'm not sure what to do about the following test failure:

mypy.....................................................................Failed
- hook id: mypy
- exit code: 1

tests/extensions/test_datacube.py:94: error: Item "None" of "Optional[Dict[str, Variable]]" has no attribute "popitem"  [union-attr]
tests/extensions/test_datacube.py:98: error: Value of type "None" is not indexable  [index]

Is there a convention for checking a @property for None, or using try/except, that I should employ here?

[duckontheweb]

I don't have a lot of experience with type hints, so I'm not sure what to do about the following test failure:

mypy.....................................................................Failed
- hook id: mypy
- exit code: 1

tests/extensions/test_datacube.py:94: error: Item "None" of "Optional[Dict[str, Variable]]" has no attribute "popitem"  [union-attr]
tests/extensions/test_datacube.py:98: error: Value of type "None" is not indexable  [index]

Is there a convention for checking a @property for None, or using try/except, that I should employ here?

We have mostly been handling this within the tests by using something like the following:

cube = DatacubeExtension.ext(item)
cube_variables = cube.variables
assert cube_variables is not None
key, value = cube_variables.popitem()

It's a bit verbose, but mypy picks up on the assert statement and knows that it can't be None after that point.

[itcarroll]

I'll include a commit updating the changelog when/if workflow approval is granted, which I presume will do the coverage check.

[duckontheweb]

Thanks for catching and fixing this @itcarroll! I'll merge once the CHANGELOG has been updated.

[itcarroll]

Added to the CHANGELOG. It looks like the coverage workflow still requires approval to run.

[itcarroll]

Coverage at 8964f5c at 94.58 equivalent to main at 07816f5e. Not sure why Codecov didn't report back here.

[duckontheweb]

Coverage at 8964f5c at 94.58 equivalent to main at 07816f5e. Not sure why Codecov didn't report back here.

Yeah, I've noticed really long lag times in Codecov posting back to the PR and sometimes it seems to take a few CI runs before it triggers. Looks like things are good on that front, thanks for the work on this!