initial commit

tests/test_criteria/test_nij.py

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+"""Tests for Nij calculation."""
+
+import pytest
+
+from impakt.channel.model import DummyInfo
+from impakt.criteria.nij import NIJ_INTERCEPTS, nij
+
+
+class TestNij:
+    def test_nij_computation(self, neck_fz_channel, neck_my_channel):
+        result = nij(fz_channel=neck_fz_channel, my_channel=neck_my_channel)
+        assert result.criterion == "Nij"
+        assert result.value > 0
+        assert result.body_region == "Neck"
+
+    def test_nij_with_channels_dict(self, neck_fz_channel, neck_my_channel):
+        result = nij(channels={"fz": neck_fz_channel, "my": neck_my_channel})
+        assert result.value > 0
+
+    def test_nij_mode_detail(self, neck_fz_channel, neck_my_channel):
+        result = nij(fz_channel=neck_fz_channel, my_channel=neck_my_channel)
+        assert "mode" in result.details
+        assert result.details["mode"] in ("NTE", "NTF", "NCE", "NCF")
+
+    def test_nij_with_dummy_info(self, neck_fz_channel, neck_my_channel):
+        dummy = DummyInfo(dummy_type="H3-50M")
+        result = nij(
+            fz_channel=neck_fz_channel,
+            my_channel=neck_my_channel,
+            dummy=dummy,
+        )
+        assert result.value > 0
+
+    def test_nij_different_dummies_give_different_results(self, neck_fz_channel, neck_my_channel):
+        result_50m = nij(
+            fz_channel=neck_fz_channel,
+            my_channel=neck_my_channel,
+            dummy=DummyInfo(dummy_type="H3-50M"),
+        )
+        result_5f = nij(
+            fz_channel=neck_fz_channel,
+            my_channel=neck_my_channel,
+            dummy=DummyInfo(dummy_type="H3-05F"),
+        )
+        # 5th female has lower intercepts, so Nij should be higher
+        assert result_5f.value > result_50m.value
+
+    def test_nij_requires_both_channels(self):
+        with pytest.raises(ValueError, match="required"):
+            nij(fz_channel=None, my_channel=None)