adding more nodes

tests/node_tests/zero_crossing.py

@@ -0,0 +1,37 @@
+import numpy as np
+import pytest
+from tests.node_tests._shared import make_field
+
+
+def test_output_binary():
+    from backend.nodes.zero_crossing import ZeroCrossing
+
+    node = ZeroCrossing()
+    field = make_field()
+    (edges,) = node.process(field, sigma=2.0, threshold=0.0)
+    unique = set(np.unique(edges.data))
+    assert unique <= {0.0, 1.0}, f"Expected only 0.0/1.0, got {unique}"
+
+
+def test_detects_step_edge():
+    from backend.nodes.zero_crossing import ZeroCrossing
+
+    node = ZeroCrossing()
+    data = np.zeros((64, 64))
+    data[:, 32:] = 1.0
+    field = make_field(data=data)
+    (edges,) = node.process(field, sigma=2.0, threshold=0.0)
+
+    # Edge energy should concentrate near column 32
+    col_energy = edges.data.sum(axis=0)
+    peak_col = np.argmax(col_energy)
+    assert abs(peak_col - 32) <= 3, f"Peak at col {peak_col}, expected ~32"
+
+
+def test_shape_preserved():
+    from backend.nodes.zero_crossing import ZeroCrossing
+
+    node = ZeroCrossing()
+    field = make_field(shape=(48, 96))
+    (edges,) = node.process(field, sigma=1.5, threshold=0.1)
+    assert edges.data.shape == (48, 96)