iso-wrapper: Handle wrong implant md5

If the checkisomd5 command exits successfully but returns a wrong value,
we should catch and log that. In theory this should be impossible, but
we have seen it in production.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

tests/test_iso_wrapper.py

@@ -0,0 +1,39 @@
+# -*- coding: utf-8 -*-
+
+import mock
+import os
+import sys
+import unittest
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
+
+from pungi.wrappers import iso
+
+CORRECT_OUTPUT = '''dummy.iso:   31ff3e405e26ad01c63b62f6b11d30f6
+Fragment sums: 6eb92e7bda221d7fe5f19b4d21468c9bf261d84c96d145d96c76444b9cbc
+Fragment count: 20
+Supported ISO: no
+'''
+
+INCORRECT_OUTPUT = '''This should never happen: File not found'''
+
+
+class TestIsoUtils(unittest.TestCase):
+    @mock.patch('pungi.wrappers.iso.run')
+    def test_get_implanted_md5_correct(self, mock_run):
+        mock_run.return_value = (0, CORRECT_OUTPUT)
+        logger = mock.Mock()
+        self.assertEqual(iso.get_implanted_md5('dummy.iso', logger=logger),
+                         '31ff3e405e26ad01c63b62f6b11d30f6')
+        self.assertEqual(mock_run.call_args_list,
+                         [mock.call(['/usr/bin/checkisomd5', '--md5sumonly', 'dummy.iso'])])
+        self.assertEqual(logger.mock_calls, [])
+
+    @mock.patch('pungi.wrappers.iso.run')
+    def test_get_implanted_md5_incorrect(self, mock_run):
+        mock_run.return_value = (0, INCORRECT_OUTPUT)
+        logger = mock.Mock()
+        self.assertIsNone(iso.get_implanted_md5('dummy.iso', logger=logger))
+        self.assertEqual(mock_run.call_args_list,
+                         [mock.call(['/usr/bin/checkisomd5', '--md5sumonly', 'dummy.iso'])])
+        self.assertGreater(len(logger.mock_calls), 0)