Warn user about enforce_type default change

We plan to change the enforce_type default to True.
https://review.openstack.org/#/c/328692

But this is going to break some project. This change
adds a deprecation warning to help them to track their broken
tests.

This should avoid people to change ton of tests file in all projects for
no real value. Specially for an option that in this end will be removed
from oslo.config when everybody have switched to the enforcing mode.

Related-Bug: #1517839

Change-Id: I438aeb766d663dbfe5dbd263fd166c25814204e8

oslo_config/cfg.py

@@ -409,6 +409,7 @@ import os
 import string
 import sys
 
+import debtcollector
 from debtcollector import removals
 import six
 from six import moves
@@ -2479,11 +2480,8 @@ class ConfigOpts(collections.Mapping):
         :raises: NoSuchOptError, NoSuchGroupError
         """
         opt_info = self._get_opt_info(name, group)
-        if enforce_type and override is not None:
-            opt_info['override'] = self._convert_value(override,
-                                                       opt_info['opt'])
-        else:
-            opt_info['override'] = override
+        opt_info['override'] = self._get_enforced_type_value(
+            opt_info['opt'], override, enforce_type)
 
     @__clear_cache
     def set_default(self, name, default, group=None, enforce_type=False):
@@ -2501,11 +2499,28 @@ class ConfigOpts(collections.Mapping):
         :raises: NoSuchOptError, NoSuchGroupError
         """
         opt_info = self._get_opt_info(name, group)
-        if enforce_type and default is not None:
-            opt_info['default'] = self._convert_value(default,
-                                                      opt_info['opt'])
+        opt_info['default'] = self._get_enforced_type_value(
+            opt_info['opt'], default, enforce_type)
+
+    def _get_enforced_type_value(self, opt, value, enforce_type):
+        if value is None:
+            return None
+        try:
+            converted = self._convert_value(value, opt)
+        except (ValueError, TypeError):
+            if enforce_type:
+                raise
+            debtcollector.deprecate(
+                "The argument enforce_type is changing its "
+                "default value to True and then will be removed completely, "
+                "please fix the invalid %s value '%s' for option '%s'."
+                % (repr(opt.type), value, opt.name),
+                version=4.0
+            )
+        if enforce_type:
+            return converted
         else:
-            opt_info['default'] = default
+            return value
 
     @__clear_cache
     def clear_override(self, name, group=None):

oslo_config/tests/test_cfg.py

@@ -2993,6 +2993,21 @@ class OverridesTestCase(BaseTestCase):
         self.conf.clear_default('foo')
         self.assertEqual('foo', self.conf.foo)
 
+    @mock.patch('debtcollector.deprecate')
+    def test_deprecation_wrong_type_default(self, deprecate):
+        self.conf.register_opt(cfg.IntOpt('foo', default=1))
+        self.conf([])
+        self.assertEqual(1, self.conf.foo)
+        self.conf.set_default('foo', "not_really_a_int")
+        self.assertEqual('not_really_a_int', self.conf.foo)
+        self.conf.clear_default('foo')
+        self.assertEqual(1, self.conf.foo)
+        deprecate.assert_called_once_with(
+            "The argument enforce_type is changing its default value to True "
+            "and then will be removed completely, please fix the invalid "
+            "Integer value 'not_really_a_int' for option 'foo'.",
+            version=4.0)
+
     def test_override(self):
         self.conf.register_opt(cfg.StrOpt('foo'))
         self.conf.set_override('foo', 'bar')
@@ -3070,6 +3085,20 @@ class OverridesTestCase(BaseTestCase):
         self.conf.clear_override('foo')
         self.assertIsNone(self.conf.foo)
 
+    @mock.patch('debtcollector.deprecate')
+    def test_deprecation_wrong_type_override(self, deprecate):
+        self.conf.register_opt(cfg.IntOpt('foo'))
+        self.conf.set_override('foo', "not_really_a_int")
+        self.conf([])
+        self.assertEqual('not_really_a_int', self.conf.foo)
+        self.conf.clear_override('foo')
+        self.assertIsNone(self.conf.foo)
+        deprecate.assert_called_once_with(
+            "The argument enforce_type is changing its default value to True "
+            "and then will be removed completely, please fix the invalid "
+            "Integer value 'not_really_a_int' for option 'foo'.",
+            version=4.0)
+
     def test_set_override_in_choices(self):
         self.conf.register_group(cfg.OptGroup('f'))
         self.conf.register_cli_opt(cfg.StrOpt('oo', choices=('a', 'b')),