bpo-29958: Minor improvements to zipfile and tarfile CLI. (#944)

diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
index 561d5fc..030ace1 100644
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -2167,6 +2167,16 @@
             for tardata in files:
                 tf.add(tardata, arcname=os.path.basename(tardata))
 
+    def test_bad_use(self):
+        rc, out, err = self.tarfilecmd_failure()
+        self.assertEqual(out, b'')
+        self.assertIn(b'usage', err.lower())
+        self.assertIn(b'error', err.lower())
+        self.assertIn(b'required', err.lower())
+        rc, out, err = self.tarfilecmd_failure('-l', '')
+        self.assertEqual(out, b'')
+        self.assertNotEqual(err.strip(), b'')
+
     def test_test_command(self):
         for tar_name in testtarnames:
             for opt in '-t', '--test':
diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py
index 47436e5..46a67d5 100644
--- a/Lib/test/test_zipfile.py
+++ b/Lib/test/test_zipfile.py
@@ -2140,6 +2140,16 @@
     def zipfilecmd_failure(self, *args):
         return script_helper.assert_python_failure('-m', 'zipfile', *args)
 
+    def test_bad_use(self):
+        rc, out, err = self.zipfilecmd_failure()
+        self.assertEqual(out, b'')
+        self.assertIn(b'usage', err.lower())
+        self.assertIn(b'error', err.lower())
+        self.assertIn(b'required', err.lower())
+        rc, out, err = self.zipfilecmd_failure('-l', '')
+        self.assertEqual(out, b'')
+        self.assertNotEqual(err.strip(), b'')
+
     def test_test_command(self):
         zip_name = findfile('zipdir.zip')
         for opt in '-t', '--test':