split node tests into standalone files

tests/node_tests/test_print_table.py

@@ -0,0 +1,18 @@
+def test_print_table():
+    from backend.nodes.print_table import PrintTable
+    node = PrintTable()
+
+    table_spec = PrintTable.INPUT_TYPES()["required"]["table"]
+    assert table_spec[0] == "RECORD_TABLE"
+    assert table_spec[1]["accepted_types"] == ["DATA_TABLE"]
+
+    captured = []
+    PrintTable._broadcast_table_fn = lambda node_id, rows: captured.append(rows)
+    PrintTable._current_node_id = "test"
+
+    table = [{"quantity": "test", "value": 42.0, "unit": "m"}]
+    node.print_table(table=table)
+    assert len(captured) == 1
+    assert captured[0] == table
+
+    PrintTable._broadcast_table_fn = None