plot_utils: make post_plot_setup set different xlabels
diff --git a/tests/test_plot_utils.py b/tests/test_plot_utils.py
index e4403fa..f09952c 100644
--- a/tests/test_plot_utils.py
+++ b/tests/test_plot_utils.py
@@ -27,6 +27,7 @@
         plot_utils.post_plot_setup(ax)
         plot_utils.post_plot_setup(ax, title="Foo")
         plot_utils.post_plot_setup(ax, ylim=(0, 72))
+        plot_utils.post_plot_setup(ax, xlabel="Bar")
 
 class TestPlotUtilsNeedTrace(TestThermalBase):
     def test_plot_allfreqs(self):