split node tests into standalone files

tests/node_tests/test_watershed_segmentation.py

@@ -0,0 +1,53 @@
+import numpy as np
+from backend.execution_context import active_node, execution_callbacks
+from tests.node_tests._shared import make_field
+
+
+def test_watershed_segmentation():
+    from scipy.ndimage import label
+    from backend.nodes.watershed_segmentation import WatershedSegmentation
+
+    node = WatershedSegmentation()
+    y, x = np.mgrid[-1:1:64j, -1:1:64j]
+    data = (
+        2.0 * np.exp(-((x + 0.45) ** 2 + y**2) / 0.05)
+        + 2.0 * np.exp(-((x - 0.45) ** 2 + y**2) / 0.05)
+        - 0.3 * np.exp(-(x**2 + y**2) / 0.12)
+    )
+    field = make_field(data=data, xreal=2.0e-6, yreal=2.0e-6)
+
+    previews = []
+    with execution_callbacks(preview=lambda nid, uri: previews.append(uri)), active_node("test"):
+        mask, = node.process(
+            field,
+            invert_height=False,
+            locate_steps=10,
+            locate_threshold=8,
+            locate_drop_size=0.1,
+            watershed_steps=20,
+            watershed_drop_size=0.1,
+            combine_mode="replace",
+        )
+    assert mask.dtype == np.uint8
+    assert mask.shape == field.data.shape
+    assert len(previews) == 1
+    assert previews[0].startswith("data:image/png;base64,")
+
+    _, ngrains = label(mask > 127)
+    assert ngrains >= 2
+
+    seed_mask = np.zeros_like(mask)
+    seed_mask[:, :32] = 255
+    intersected, = node.process(
+        field,
+        invert_height=False,
+        locate_steps=10,
+        locate_threshold=8,
+        locate_drop_size=0.1,
+        watershed_steps=20,
+        watershed_drop_size=0.1,
+        combine_mode="intersection",
+        mask=seed_mask,
+    )
+    assert np.count_nonzero(intersected) < np.count_nonzero(mask)
+    assert np.all(intersected[:, 40:] == 0)