Disable bias correction in degenerate GMM test (#150)

Brandon Kirkland · Brandon Kirkland · commit cd2041b8ffb2 · 2026-04-03T08:09:42.000-06:00
N4 bias correction on uniform-intensity data introduces numerical
variation that prevents the near-zero ptp guard from triggering.
Disabling it ensures the test exercises the intended code path.
diff --git a/tests/test_threshold_mri.py b/tests/test_threshold_mri.py
@@ -298,6 +298,7 @@ def test_classify_brain_degenerate_constant_intensity() -> None:
         classify_brain_tissues=True,
         air_threshold_quantile=0.0,
         skull_thickness_mm=7.0,
+        bias_correction_sigma_mm=0.0,
     )
     result = seg._segment(volume)
     idx = seg._material_indices()

Original file line number	Diff line number	Diff line change
`@@ -298,6 +298,7 @@ def test_classify_brain_degenerate_constant_intensity() -> None:`
`298`	`298`	`classify_brain_tissues=True,`
`299`	`299`	`air_threshold_quantile=0.0,`
`300`	`300`	`skull_thickness_mm=7.0,`
	`301`	`+ bias_correction_sigma_mm=0.0,`
`301`	`302`	`)`
`302`	`303`	`result = seg._segment(volume)`
`303`	`304`	`idx = seg._material_indices()`