test: Add test for iterator exhaustion with next

* Add test to tests/contrib/test_viz.py to cover the case where the
  wrong labels are somehow returned in brazil.plot_results, causing the
  legend label ordering logic to fail.
* Amends PR # 2264

tests/contrib/test_viz.py

@@ -181,3 +181,25 @@ def test_plot_results_components_data_structure(datadir):
  brazil.plot_results(
  data["testmus"], data["results"], test_size=0.05, ax=ax, components=True
  )
+
+
+def test_plot_results_wrong_axis_labels(datadir, mocker):
+ """
+ If the returned labels are different from the expected, then the hardcoded
+ values in label_part will be wrong, causing `next` to fail on the iterator
+ for label_idx.
+ """
+ data = json.load(datadir.joinpath("hypotest_results.json").open(encoding="utf-8"))
+
+ fig = Figure()
+ ax = fig.subplots()
+
+ get_legend_handles_labels = mocker.patch(
+ "matplotlib.axes._axes.Axes.get_legend_handles_labels",
+ return_value=(None, ["fail"]),
+ )
+
+ with pytest.raises(StopIteration):
+ brazil.plot_results(data["testmus"], data["results"], test_size=0.05, ax=ax)
+
+ assert get_legend_handles_labels.called