tidy up old code

tests/node_tests/mask_threshold.py

@@ -10,30 +10,27 @@ def test_threshold_mask():
     data[:, 32:] = 1.0
     field = make_field(data=data)
 
+    from backend.execution_context import execution_callbacks, active_node
     previews = []
-    ThresholdMask._broadcast_fn = lambda nid, uri: previews.append(uri)
-    ThresholdMask._current_node_id = "test"
+    with execution_callbacks(preview=lambda nid, uri: previews.append(uri)), active_node("test"):
+        mask, table = node.process(field, method="absolute", threshold=0.5, direction="above")
+        assert mask.dtype == np.uint8
+        assert mask.shape == (64, 64)
+        assert np.all(mask[:, :32] == 0)
+        assert np.all(mask[:, 32:] == 255)
 
-    mask, table = node.process(field, method="absolute", threshold=0.5, direction="above")
-    assert mask.dtype == np.uint8
-    assert mask.shape == (64, 64)
-    assert np.all(mask[:, :32] == 0)
-    assert np.all(mask[:, 32:] == 255)
+        assert len(previews) == 1
+        assert previews[0].startswith("data:image/png;base64,")
 
-    assert len(previews) == 1
-    assert previews[0].startswith("data:image/png;base64,")
+        mask_below, _ = node.process(field, method="absolute", threshold=0.5, direction="below")
+        assert np.all(mask_below[:, :32] == 255)
+        assert np.all(mask_below[:, 32:] == 0)
 
-    mask_below, _ = node.process(field, method="absolute", threshold=0.5, direction="below")
-    assert np.all(mask_below[:, :32] == 255)
-    assert np.all(mask_below[:, 32:] == 0)
+        mask_rel, _ = node.process(field, method="relative", threshold=0.5, direction="above")
+        assert np.all(mask_rel[:, 32:] == 255)
 
-    mask_rel, _ = node.process(field, method="relative", threshold=0.5, direction="above")
-    assert np.all(mask_rel[:, 32:] == 255)
-
-    mask_otsu, _ = node.process(field, method="otsu", threshold=0.0, direction="above")
-    assert mask_otsu[:, 32:].sum() > mask_otsu[:, :32].sum()
-
-    ThresholdMask._broadcast_fn = None
+        mask_otsu, _ = node.process(field, method="otsu", threshold=0.0, direction="above")
+        assert mask_otsu[:, 32:].sum() > mask_otsu[:, :32].sum()
 
 
 def test_threshold_mask_unknown_method():