test: add neither-axis-LR edge case + document swap pass-through

explorer.py

@@ -193,6 +193,7 @@ def _swap_axes(
         new_positions[wid] = {ent: (y, x) for ent, (x, y) in pos_dict.items()}
 
     new_ax = dict(axis_def)
+    # Non-paired keys pass through unchanged
     # Swap paired scalar keys
     new_ax["x_label"] = axis_def.get("y_label")
     new_ax["y_label"] = axis_def.get("x_label")

tests/test_political_compass.py

@@ -724,3 +724,10 @@ def test_axis_swap_not_applied_when_x_is_left_right():
         "y_label": "Links\u2013Rechts",  # both LR — no swap
     }
     assert _should_swap_axes(axis_def2) is False
+
+
+def test_axis_swap_not_applied_when_neither_axis_is_left_right():
+    from explorer import _should_swap_axes
+
+    assert _should_swap_axes({"x_label": "Foo", "y_label": "Bar"}) is False
+    assert _should_swap_axes({"x_label": None, "y_label": None}) is False