tests: don't store the return of plot_cluster_load()
diff --git a/tests/test_power.py b/tests/test_power.py
index f9cac68..ddd0c01 100644
--- a/tests/test_power.py
+++ b/tests/test_power.py
@@ -28,4 +28,4 @@
 
     def test_inpower_plot_cluster_load(self):
         """Test that InPower.plot_cluster_load() doesn't explode"""
-        df = InPower().plot_cluster_load(0)
+        InPower().plot_cluster_load(0)