Check if type of list elements are strings

The members of lists specified in the YAML configuration for mmdebstrap
are expected to be strings. Add a check for that to prevent mmdebstrap
from failing due to malformed parameters.

Signed-off-by: Benjamin Drung <[email protected]>

bdebstrap

@@ -586,6 +586,14 @@ class Config(dict):
                         "Unexpected type '%s' for mmdebstrap option '%s'. "
                         "Excepted: %s." % (type(value), key, MMDEBSTRAP_OPTS[key])
                     )
+                if MMDEBSTRAP_OPTS[key] is list:
+                    # Check if list elements are strings
+                    for element in value:
+                        if not isinstance(element, str):
+                            raise ValueError(
+                                "Following list element of mmdebstrap option '%s' has type '%s' "
+                                "instead of string: %s" % (key, type(element).__name__, element)
+                            )
         else:
             self.logger.warning("The configuration does not contain a 'mmdebstrap' entry.")
 

tests/configs/wrong-element-type.yaml

@@ -0,0 +1,7 @@
+name: wrong-element-type
+mmdebstrap:
+  customize-hooks:
+  # Make vim the default editor
+  - chroot "$1" update-alternatives --set editor /usr/bin/vim.basic
+  # Passwordless sudo
+  - sed -i 's/^%sudo.*$/%sudo   ALL=(ALL:ALL) NOPASSWD: ALL/' "$1/etc/sudoers"

tests/test_config.py

@@ -369,6 +369,13 @@ def test_source_date_epoch(self):
             config.set_source_date_epoch()
         self.assertEqual(config.source_date_epoch, 1581694618)
 
+    def test_wrong_element_type(self):
+        """Test error message for wrong list element type."""
+        config = Config()
+        config.load(os.path.join(TEST_CONFIG_DIR, "wrong-element-type.yaml"))
+        with self.assertRaisesRegex(ValueError, "'customize-hooks' has type 'CommentedMap'"):
+            config.check()
+
 
 class TestDictMerge(unittest.TestCase):
     """Unittests for dict_merge function."""