Make newsletter exercise tests run async

[halfdan]

I just went through this exercise as part of the Exhort. It seemed trivial to make this exercise run tests asynchronous by generating random temp files using some core utils.

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Automated comment created by PR Commenter 🤖.

[zorn]

My understanding is that marking a test module as async only enables concurrent testing against other modules. The individual tests of a single module always run sequentially. 🤷‍♂️

https://hexdocs.pm/ex_unit/main/ExUnit.Case.html

[angelikatyborska]

@zorn You're absolutely right. This existing code with the comment in the tests should never have been added:

  # run test synchronously to be able to use the same file path for all tests without write conflicts
  use ExUnit.Case, async: false

Our bad 🙈. But that also means this PR isn't really needed. We just need to remove the snippet I posted above to avoid future confusion.

[halfdan]

Hah, well TIL.

Happy to update/change the PR to remove that little snippet. Thanks to both of you.

[angelikatyborska]

Happy to update/change the PR to remove that little snippet

That would be much appreciated!

[jiegillet]

@halfdan are you still interested in finishing this PR? We can add the hacktoberfest label to it if you're interested.

[halfdan]

Yep, still happy to finish this. The tag would be a nice perk.

[halfdan]

@jiegillet Perfectly fine - sorry for dropping the ball here.