tidy up old code

tests/node_tests/cursors.py

@@ -12,53 +12,50 @@ def test_line_cursors():
 
     line = np.linspace(0, 10, 100).astype(np.float64)
 
+    from backend.execution_context import execution_callbacks, active_node
     overlays = []
-    Cursors._broadcast_overlay_fn = lambda nid, data: overlays.append(data)
-    Cursors._current_node_id = "test"
+    with execution_callbacks(overlay=lambda nid, data: overlays.append(data)), active_node("test"):
+        table, coord_pair = node.process(line, x1=0.25, y1=0.5, x2=0.75, y2=0.5)
+        assert isinstance(coord_pair, tuple) and len(coord_pair) == 2
+        assert len(table) == 7
+        quantities = {row["quantity"] for row in table}
+        assert "Length" in quantities
+        assert "A x" in quantities
+        assert "B x" in quantities
+        assert "dx" in quantities
+        assert "dy" in quantities
 
-    table, coord_pair = node.process(line, x1=0.25, y1=0.5, x2=0.75, y2=0.5)
-    assert isinstance(coord_pair, tuple) and len(coord_pair) == 2
-    assert len(table) == 7
-    quantities = {row["quantity"] for row in table}
-    assert "Length" in quantities
-    assert "A x" in quantities
-    assert "B x" in quantities
-    assert "dx" in quantities
-    assert "dy" in quantities
+        a_pos = next(r["value"] for r in table if r["quantity"] == "A x")
+        b_pos = next(r["value"] for r in table if r["quantity"] == "B x")
+        assert b_pos > a_pos
 
-    a_pos = next(r["value"] for r in table if r["quantity"] == "A x")
-    b_pos = next(r["value"] for r in table if r["quantity"] == "B x")
-    assert b_pos > a_pos
+        dy = next(r["value"] for r in table if r["quantity"] == "dy")
+        assert dy > 0
 
-    dy = next(r["value"] for r in table if r["quantity"] == "dy")
-    assert dy > 0
+        assert len(overlays) == 1
+        assert overlays[0]["kind"] == "line_plot"
+        assert len(overlays[0]["line"]) == len(line)
+        assert len(overlays[0]["x_axis"]) == len(line)
+        assert 0.0 <= overlays[0]["x1"] <= 1.0
+        assert 0.0 <= overlays[0]["x2"] <= 1.0
 
-    assert len(overlays) == 1
-    assert overlays[0]["kind"] == "line_plot"
-    assert len(overlays[0]["line"]) == len(line)
-    assert len(overlays[0]["x_axis"]) == len(line)
-    assert 0.0 <= overlays[0]["x1"] <= 1.0
-    assert 0.0 <= overlays[0]["x2"] <= 1.0
+        line_data = LineData(data=line, x_axis=np.linspace(0, 1, 100))
+        table2, _ = node.process(line_data, x1=0.25, y1=0.5, x2=0.75, y2=0.5)
+        assert len(table2) == 7
 
-    line_data = LineData(data=line, x_axis=np.linspace(0, 1, 100))
-    table2, _ = node.process(line_data, x1=0.25, y1=0.5, x2=0.75, y2=0.5)
-    assert len(table2) == 7
-
-    field = DataField(
-        data=np.arange(100, dtype=np.float64).reshape(10, 10),
-        xreal=2.0, yreal=4.0, si_unit_xy="um", si_unit_z="nm",
-    )
-    overlays.clear()
-    table3, _ = node.process(field, x1=0.2, y1=0.25, x2=0.7, y2=0.75)
-    assert len(table3) == 9
-    field_rows = {row["quantity"]: row for row in table3}
-    assert field_rows["dx"]["unit"] == "um"
-    assert field_rows["dy"]["unit"] == "um"
-    assert field_rows["dz"]["unit"] == "nm"
-    assert np.isclose(field_rows["dx"]["value"], 1.0)
-    assert np.isclose(field_rows["dy"]["value"], 2.0)
-    assert len(overlays) == 1
-    assert overlays[0]["kind"] == "cursor_points"
-    assert overlays[0]["image"].startswith("data:image/png;base64,")
-
-    Cursors._broadcast_overlay_fn = None
+        field = DataField(
+            data=np.arange(100, dtype=np.float64).reshape(10, 10),
+            xreal=2.0, yreal=4.0, si_unit_xy="um", si_unit_z="nm",
+        )
+        overlays.clear()
+        table3, _ = node.process(field, x1=0.2, y1=0.25, x2=0.7, y2=0.75)
+        assert len(table3) == 9
+        field_rows = {row["quantity"]: row for row in table3}
+        assert field_rows["dx"]["unit"] == "um"
+        assert field_rows["dy"]["unit"] == "um"
+        assert field_rows["dz"]["unit"] == "nm"
+        assert np.isclose(field_rows["dx"]["value"], 1.0)
+        assert np.isclose(field_rows["dy"]["value"], 2.0)
+        assert len(overlays) == 1
+        assert overlays[0]["kind"] == "cursor_points"
+        assert overlays[0]["image"].startswith("data:image/png;base64,")