Fix flaky test_json_serialization by using deterministic test data

[Copilot]

The test_json_serialization test intermittently fails in CI with relative differences ~1.13e-07, exceeding the default assert_allclose tolerance of 1e-07. This occurs due to non-deterministic random data generation in the test.

Changes

• tests/light_curve_ext/test_feature.py: Added fixed random seed rng=0 to gen_lc() call to ensure deterministic test data generation

# Before
data = gen_lc(n_obs)
assert_allclose(values, values_from_to_json)

# After  
data = gen_lc(n_obs, rng=0)
assert_allclose(values, values_from_to_json)

This approach makes the test fully deterministic by ensuring the same random data is generated every run, eliminating flakiness at the source while maintaining the strict default tolerance (rtol=1e-7). This is consistent with the test parametrization which already uses rng=0 for feature generation.

• Fixes Test failure in CI #581

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Test failure in CI</issue_title>
<issue_description>Some test sometimes fails in CI. We should either make it more deterministic, or set much larger rtol, or remake it. Or find a bug =)

tests/light_curve_ext/test_feature.py:434: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

args = (<function assert_allclose.<locals>.compare at 0x7f6420a18c10>, array([ 9.09579623e+00, -5.40383904e+00, -8.64983171e-...904e+00, -8.64983172e-01,  2.19817431e+00,
        8.17213286e+01,  1.27377227e-04,  2.04551540e+00,  8.13644738e-01]))
kwds = {'equal_nan': True, 'err_msg': '', 'header': 'Not equal to tolerance rtol=1e-07, atol=0', 'strict': False, ...}

    @wraps(func)
    def inner(*args, **kwds):
        with self._recreate_cm():
>           return func(*args, **kwds)
E           AssertionError: 
E           Not equal to tolerance rtol=1e-07, atol=0
E           
E           Mismatched elements: 1 / 8 (12.5%)
E           Max absolute difference among violations: 1.43896006e-11
E           Max relative difference among violations: 1.12968393e-07
E            ACTUAL: array([ 9.095796e+00, -5.403839e+00, -8.649832e-01,  2.198174e+00,
E                   8.172133e+01,  1.273772e-04,  2.045515e+00,  8.136447e-01])
E            DESIRED: array([ 9.095796e+00, -5.403839e+00, -8.649832e-01,  2.198174e+00,
E                   8.172133e+01,  1.273772e-04,  2.045515e+00,  8.136447e-01])

https://github.com/light-curve/light-curve-python/actions/runs/19382889947/job/55464766907?pr=576</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Test failure in CI #581

---

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[hombit]

@copilot let's better try to use gen_lc with fixed random seed

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.60%. Comparing base (94c6faa) to head (9837bda).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #582   +/-   ##
=======================================
  Coverage   82.60%   82.60%           
=======================================
  Files           9        9           
  Lines        2604     2604           
=======================================
  Hits         2151     2151           
  Misses        453      453           

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[Copilot]

@copilot let's better try to use gen_lc with fixed random seed

Done in b9fe806. Changed gen_lc(n_obs) to gen_lc(n_obs, rng=0) to use deterministic test data, and reverted the tolerance relaxation to keep the default strict checking.

[codspeed-hq]

CodSpeed Performance Report

Merging #582 will not alter performance

_{Comparing copilot/fix-ci-test-failure (9837bda) with master (94c6faa)}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

✅ 106 untouched
⏩ 106 skipped¹

Footnotes

1. 106 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩