add tests for DefaultIfNone validator

deruyter92 · Sep 8, 2026 · Sep 1, 2026 · Sep 1, 2026 · Sep 1, 2026 · Sep 1, 2026
commit aa4bedca631a471431944e63eddd17a9358e6b76
diff --git a/tests/core/config/test_validation.py b/tests/core/config/test_validation.py
@@ -0,0 +1,58 @@
+#
+# DeepLabCut Toolbox (deeplabcut.org)
+# © A. & M.W. Mathis Labs
+# https://github.com/DeepLabCut/DeepLabCut
+#
+# Licensed under GNU Lesser General Public License v3.0
+#
+"""Tests for the annotated types in deeplabcut.core.config.validation."""
+
+import pytest
+from pydantic import ValidationError
+
+from deeplabcut.core.config import DLCBaseConfig
+from deeplabcut.core.config.validation import DefaultIfNone, Fraction
+
+
+class ThresholdConfig(DLCBaseConfig):
+    """Config exercising DefaultIfNone over a constrained type."""
+
+    threshold: DefaultIfNone[Fraction] = 0.01
+    name: DefaultIfNone[str] = "detector"
+
+
+# ------------------------------------------------------------------
+# DefaultIfNone
+# ------------------------------------------------------------------
+
+
+class TestDefaultIfNone:
+    def test_none_falls_back_to_default(self):
+        assert ThresholdConfig(threshold=None).threshold == 0.01
+
+    def test_explicit_value_is_kept(self):
+        assert ThresholdConfig(threshold=0.6).threshold == 0.6
+
+    def test_falsy_value_is_kept(self):
+        # A plain ``value or default`` would silently turn 0.0 into the default.
+        assert ThresholdConfig(threshold=0.0).threshold == 0.0
+
+    def test_applies_to_any_wrapped_type(self):
+        assert ThresholdConfig(name=None).name == "detector"
+        assert ThresholdConfig(name="ssdlite").name == "ssdlite"
+
+    def test_wrapped_annotation_is_not_swallowed(self):
+        # The generic alias must compose with Fraction, not replace it.
+        with pytest.raises(ValidationError):
+            ThresholdConfig(threshold=1.5)
+
+    def test_none_is_normalized_on_assignment(self):
+        # DLCBaseConfig sets validate_assignment=True, so the validator runs here too.
+        cfg = ThresholdConfig(threshold=0.6)
+        cfg.threshold = None
+        assert cfg.threshold == 0.01
+
+    def test_default_is_serialized_instead_of_none(self):
+        # The null must not survive a load/save round trip.
+        cfg = ThresholdConfig.from_dict({"threshold": None})
+        assert cfg.to_dict()["threshold"] == 0.01