Improve presimulation test

[FFroehlich]

Summary

• ensure test_presimulation actually runs presimulation
• verify gradients are nonzero
• add more observables to presimulation fixture

Testing

• pre-commit run --files python/tests/test_sbml_import.py python/tests/conftest.py
• pytest python/tests/test_sbml_import.py::test_presimulation -q

---

https://chatgpt.com/codex/tasks/task_b_685d25fb7768832b840af6f1e4437acb

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.18%. Comparing base (82d53b4) to head (6e53c63).
Report is 8 commits behind head on main.

❗ There is a different number of reports uploaded between BASE (82d53b4) and HEAD (6e53c63). Click for more details.

HEAD has 71 uploads less than BASE

Flag	BASE (82d53b4)	HEAD (6e53c63)
petab	2	1
python	38	1
cpp_python	15	0
cpp	15	0
sbmlsuite-jax	3	0

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2837      +/-   ##
==========================================
- Coverage   80.97%   74.18%   -6.80%     
==========================================
  Files         328      329       +1     
  Lines       22405    21695     -710     
  Branches     1515     1505      -10     
==========================================
- Hits        18142    16094    -2048     
- Misses       4252     4970     +718     
- Partials       11      631     +620     

Flag	Coverage Δ
cpp	?
cpp_python	?
petab	39.25% <ø> (-0.07%)	⬇️
python	71.82% <ø> (-3.34%)	⬇️
sbmlsuite-jax	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
python/tests/conftest.py	41.37% <ø> (ø)

... and 62 files with indirect coverage changes

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud