Add an error log before raise UnparsedFlagAccessError in Python 2.

This is to make hasattr callers be more aware of the issue, since hasattr silences the exception and returns False in Python 2.

Also make the message more clear on what the flag name is, otherwise if the flag is called "metadata" and the message "Trying to access flag metadata before flags were parsed." is confusing.

PiperOrigin-RevId: 170214560

1 files changed, 30 insertions, 10 deletions

diff --git a/absl/flags/tests/_flagvalues_test.py b/absl/flags/tests/_flagvalues_test.py
index 3f94332..d0fb927 100644
--- a/absl/flags/tests/_flagvalues_test.py
+++ b/absl/flags/tests/_flagvalues_test.py
@@ -19,6 +19,7 @@ from __future__ import division
 from __future__ import print_function
 
 import types
+import unittest
 
 from absl import logging
 from absl.flags import _defines
@@ -29,6 +30,7 @@ from absl.flags.tests import module_foo
 from absl.testing import absltest
 from absl.testing import parameterized
 import mock
+import six
 
 
 class FlagValuesTest(absltest.TestCase):
@@ -566,15 +568,6 @@ class FlagsDashSyntaxTest(absltest.TestCase):
 
 class UnparseFlagsTest(absltest.TestCase):
 
-  def test_unparsed_flags_access_raises_after_unparse_flags(self):
-    fv = _flagvalues.FlagValues()
-    _defines.DEFINE_string('a_str', 'default_value', 'help', flag_values=fv)
-    fv.mark_as_parsed()
-    self.assertEqual(fv.a_str, 'default_value')
-    fv.unparse_flags()
-    with self.assertRaises(_exceptions.UnparsedFlagAccessError):
-      _ = fv.a_str
-
   def test_using_default_value_none(self):
     fv = _flagvalues.FlagValues()
     _defines.DEFINE_string('default_none', None, 'help', flag_values=fv)
@@ -675,12 +668,39 @@ class UnparseFlagsTest(absltest.TestCase):
     fv.unparse_flags()
     self.assertEqual(expected_default, fv['foo'].value)
 
-  def test_unitialized_flag_access(self):
+
+class UnparsedFlagAccessTest(absltest.TestCase):
+
+  def test_unparsed_flag_access(self):
     fv = _flagvalues.FlagValues()
     _defines.DEFINE_string('name', 'default', 'help', flag_values=fv)
     with self.assertRaises(_exceptions.UnparsedFlagAccessError):
       _ = fv.name
 
+  @unittest.skipIf(six.PY3, 'Python 2 only test')
+  def test_hasattr_logs_in_py2(self):
+    fv = _flagvalues.FlagValues()
+    _defines.DEFINE_string('name', 'default', 'help', flag_values=fv)
+    with mock.patch.object(_flagvalues.logging, 'error') as mock_error:
+      self.assertFalse(hasattr(fv, 'name'))
+    mock_error.assert_called_once()
+
+  @unittest.skipIf(six.PY2, 'Python 3 only test')
+  def test_hasattr_raises_in_py3(self):
+    fv = _flagvalues.FlagValues()
+    _defines.DEFINE_string('name', 'default', 'help', flag_values=fv)
+    with self.assertRaises(_exceptions.UnparsedFlagAccessError):
+      _ = hasattr(fv, 'name')
+
+  def test_unparsed_flags_access_raises_after_unparse_flags(self):
+    fv = _flagvalues.FlagValues()
+    _defines.DEFINE_string('a_str', 'default_value', 'help', flag_values=fv)
+    fv.mark_as_parsed()
+    self.assertEqual(fv.a_str, 'default_value')
+    fv.unparse_flags()
+    with self.assertRaises(_exceptions.UnparsedFlagAccessError):
+      _ = fv.a_str
+
 
 if __name__ == '__main__':
   absltest.main()