Fix type errors

[adamchainz]

First, Mypy reported a lot of issues for the tests not including -> None annotations. After adding them, there were lots of issues due to the url variables being reassigned from str to DBConfig objects, fixed by inlining the URLs into the parse() calls.

Extracted from #260.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (5106a19) to head (621806f).
Report is 18 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #261   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines           76        75    -1     
  Branches        18        18           
=========================================
- Hits            76        75    -1     

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[palfrey]

First, Mypy reported a lot of issues for the tests not including -> None annotations

I'm not seeing any issues with mypy? Either in a 2 weeks ago CI run, or a local check with 1.15.0, all seemed fine.

Well, until I added tests to the list :) Can you fix the Run type checking step so this problem occurs in CI, and then I'd be happy to merge it.

[adamchainz]

It failed in the original PR that I extracted this from. See e.g. https://github.com/jazzband/dj-database-url/actions/runs/13328951144/job/37228430699?pr=260

This step already runs Mypy on the test directory:

dj-database-url/.github/workflows/test.yml

Lines 51 to 56 in 8501773

	- name: Check types installation
	run: |
	pip install .
	cd tests
	python -m mypy .
	python -m pyright .

Either in a 2 weeks ago CI run

That run was just before Mypy 1.15 was released the next day. So maybe 1.15 was the trigger?

[palfrey]

Yup, it's 1.15. See https://github.com/jazzband/dj-database-url/actions/runs/13120012093/job/37291897743