Fixed database typo and removed unnecessary class identifier.

venv/Lib/site-packages/matplotlib/tests/test_sankey.py

@@ -0,0 +1,12 @@
+from matplotlib.sankey import Sankey
+
+
+def test_sankey():
+    # lets just create a sankey instance and check the code runs
+    sankey = Sankey()
+    sankey.add()
+
+
+def test_label():
+    s = Sankey(flows=[0.25], labels=['First'], orientations=[-1])
+    assert s.diagrams[0].texts[0].get_text() == 'First\n0.25'