Issue #16793. Replace deprecated unittest asserts with modern counterparts.
diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
index a3685ea..9ec7744 100644
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -858,7 +858,7 @@
 
             tar = tarfile.open(tmpname, "r")
             for t in tar:
-                self.assert_(t.name == "." or t.name.startswith("./"))
+                self.assertTrue(t.name == "." or t.name.startswith("./"))
             tar.close()
         finally:
             os.chdir(cwd)