create unittest for warning

diff --git a/testing/test_multivol.py b/testing/test_multivol.py
index 9896295..7afe2ef 100644 (file)
--- a/testing/test_multivol.py
+++ b/testing/test_multivol.py
@@ -219,6 +219,15 @@ class MultivolGnuFormatTest(BaseTest):
         assert max_err < 13*1024
         assert max_err_post == 0
 
+    def test_multivol_compress_warning(self):
+        """ check warning being issued if compressing multivolume with w: """
+        with self.assertWarns(UserWarning):
+            tarobj = TarFile.open("sample.tar.gz",
+                                  mode="w:gz",
+                                  format=self.tarfile_format,
+                                  max_volume_size=30000,
+                                  new_volume_handler=new_volume_handler)
+
     def test_multivol_compress(self):
         ''' check creation of multiple volume when compression is on '''