Add a writer_kwargs argument to MDAReporter and speed up testing

[orionarcher]

Fixes #6

Changes made in this Pull Request:

• format code with Black
• added a writer_kwargs argument to MDAReporter that is passed to mda.Writer
• migrate testing to use serialized simulation instead of re-instantiating each time. Much faster, all tests pass locally.

PR Checklist

• Tests?
• Docs?
• CHANGELOG updated?
• Issue raised/referenced?

[orionarcher]

Would love a look from @richardjgowers or @sef43 when y'all have time! I think the changes are pretty innocuous and would help me solve a downstream use case.

[sef43]

Thanks for the contribution!, can this please be re-done without the formatting changes please? The formating change should be a seperate PR.

[codecov-commenter]

Codecov Report

Merging #7 (f2ecd4f) into main (d665b3d) will decrease coverage by 31.09%.
The diff coverage is 37.83%.

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Additional details and impacted files

[orionarcher]

Are you opened to the formatting changes? I opened a PR #8 with just the Black formatting.

If possible, I'd like to merge that and then reopen this PR so I don't have to sort out the logic from formatting changes. (A little lazy I admit.)

[sef43]

Currently yes I am against the formatting changes to any of the existing files. The current formatting follows the openmm formatting for Reporter classes. There is no reason to deviate from this.

I don't have to sort out the logic from formatting changes.

As you point out here the key issue is that the unnecessary formatting changes obscure the functional changes to the code. I think MDAnalysis does not allow black formatting of existing code, only new code, for this reason.
MDAnalysis/mdanalysis#2450

[orionarcher]

Fair enough, I understand the desire to avoid black and stay compatible with upstream formatting.

I added a new PR #9 that implements the testing and kwargs changes without the black formatting.