Fix testcase for invalid value at node initialization

[christophfroehlich]

Since PickNikRobotics/generate_parameter_library#339 the behavior of generate_parameter_library changed.
The parameter in the testcase can't even be declared as zero now (earlier it was declared with 0 but the validator failed later).

2026-05-18T07:35:36.9553861Z     [ RUN      ] FilterTest.TestLowPassWrenchFilterInvalidThenFixedParameter
2026-05-18T07:35:36.9555026Z     [ERROR] [1779089735.022610158] [TestLowPassWrenchFilterInvalidThenFixedParameter.TestLowPassFilter]: LowPass filter cannot be configured: parameter 'sampling_frequency' could not be set: Parameter {sampling_frequency} doesn't comply with floating point range. (type : N6rclcpp10exceptions30InvalidParameterValueExceptionE)
2026-05-18T07:35:36.9556068Z     unknown file: Failure
2026-05-18T07:35:36.9556522Z     C++ exception with description "parameter 'sampling_frequency' cannot be set because it was not declared" thrown in the test body.
2026-05-18T07:35:36.9556934Z     
2026-05-18T07:35:36.9557232Z     [  FAILED  ] FilterTest.TestLowPassWrenchFilterInvalidThenFixedParameter (7 ms)

Is this user-facing behavior change?

no

Did you use Generative AI?

no

[saikishor]

I don't get why the parameter failed to declare

[christophfroehlich]

The parameter description is updated with correct limits using the rclcpp API. This now fails early at the time of parameter declaration. The test wasn't designed properly here.

[christophfroehlich]

But I need to release generate_parameter_library to make the new test succeed.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.60%. Comparing base (0bd9f25) to head (ee8feb0).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #615      +/-   ##
==========================================
- Coverage   83.61%   83.60%   -0.01%     
==========================================
  Files          31       31              
  Lines        2203     2202       -1     
  Branches      128      126       -2     
==========================================
- Hits         1842     1841       -1     
  Misses        277      277              
  Partials       84       84              

Flag	Coverage Δ
unittests	83.60% <100.00%> (-0.01%)	⬇️

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

Files with missing lines	Coverage Δ
...lbox/test/control_filters/test_low_pass_filter.cpp	100.00% <100.00%> (ø)

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