Use "x in y" instead of y.find(x) != -1.
diff --git a/Lib/test/test_minidom.py b/Lib/test/test_minidom.py
index fad7f36..f160d09 100644
--- a/Lib/test/test_minidom.py
+++ b/Lib/test/test_minidom.py
@@ -433,7 +433,7 @@
         string1 = repr(el)
         string2 = str(el)
         self.confirm(string1 == string2)
-        self.confirm(string1.find("slash:abc") != -1)
+        self.confirm("slash:abc" in string1)
         dom.unlink()
 
     def testAttributeRepr(self):