Make absl flags integrate with argparse.

Argparse support is provided by two pieces: an argparse-compatible parser that
understands absl flags, and app.run accepting a custom flag parser.

argparse_flags.ArgumentParser is a custom argparse.ArgumentParser that
makes absl defined flags available via the argparse APIs. The argparse_flags
module contains more documentation.

app.run accepts a flags_parser argument, which is responsible for parsing
command line args and returning the value to pass onto main. The app.run
function contains more documentation.

Resolves issue #27

PiperOrigin-RevId: 208509632

1 files changed, 443 insertions, 0 deletions

diff --git a/absl/flags/tests/argparse_flags_test.py b/absl/flags/tests/argparse_flags_test.py
new file mode 100644
index 0000000..244f977
--- /dev/null
+++ b/absl/flags/tests/argparse_flags_test.py
@@ -0,0 +1,443 @@
+# Copyright 2018 The Abseil Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Tests for absl.flags.argparse_flags."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import os
+import subprocess
+import sys
+import tempfile
+
+from absl import flags
+from absl import logging
+from absl.flags import argparse_flags
+from absl.testing import _bazelize_command
+from absl.testing import absltest
+from absl.testing import parameterized
+import mock
+import six
+
+
+FLAGS = flags.FLAGS
+
+
+class ArgparseFlagsTest(parameterized.TestCase):
+
+  def setUp(self):
+    self._absl_flags = flags.FlagValues()
+    flags.DEFINE_bool(
+        'absl_bool', None, 'help for --absl_bool.',
+        short_name='b', flag_values=self._absl_flags)
+    # Add a boolean flag that starts with "no", to verify it can correctly
+    # handle the "no" prefixes in boolean flags.
+    flags.DEFINE_bool(
+        'notice', None, 'help for --notice.',
+        flag_values=self._absl_flags)
+    flags.DEFINE_string(
+        'absl_string', 'default', 'help for --absl_string=%.',
+        short_name='s', flag_values=self._absl_flags)
+    flags.DEFINE_integer(
+        'absl_integer', 1, 'help for --absl_integer.',
+        flag_values=self._absl_flags)
+    flags.DEFINE_float(
+        'absl_float', 1, 'help for --absl_integer.',
+        flag_values=self._absl_flags)
+    flags.DEFINE_enum(
+        'absl_enum', 'apple', ['apple', 'orange'], 'help for --absl_enum.',
+        flag_values=self._absl_flags)
+
+  def test_dash_as_prefix_char_only(self):
+    with self.assertRaises(ValueError):
+      argparse_flags.ArgumentParser(prefix_chars='/')
+
+  def test_default_inherited_absl_flags_value(self):
+    parser = argparse_flags.ArgumentParser()
+    self.assertIs(parser._inherited_absl_flags, flags.FLAGS)
+
+  def test_parse_absl_flags(self):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    self.assertFalse(self._absl_flags.is_parsed())
+    self.assertTrue(self._absl_flags['absl_string'].using_default_value)
+    self.assertTrue(self._absl_flags['absl_integer'].using_default_value)
+    self.assertTrue(self._absl_flags['absl_float'].using_default_value)
+    self.assertTrue(self._absl_flags['absl_enum'].using_default_value)
+
+    parser.parse_args(
+        ['--absl_string=new_string', '--absl_integer', '2'])
+    self.assertEqual(self._absl_flags.absl_string, 'new_string')
+    self.assertEqual(self._absl_flags.absl_integer, 2)
+    self.assertTrue(self._absl_flags.is_parsed())
+    self.assertFalse(self._absl_flags['absl_string'].using_default_value)
+    self.assertFalse(self._absl_flags['absl_integer'].using_default_value)
+    self.assertTrue(self._absl_flags['absl_float'].using_default_value)
+    self.assertTrue(self._absl_flags['absl_enum'].using_default_value)
+
+  @parameterized.named_parameters(
+      ('true', ['--absl_bool'], True),
+      ('false', ['--noabsl_bool'], False),
+      ('does_not_accept_equal_value', ['--absl_bool=true'], SystemExit),
+      ('does_not_accept_space_value', ['--absl_bool', 'true'], SystemExit),
+      ('long_name_single_dash', ['-absl_bool'], SystemExit),
+      ('short_name', ['-b'], True),
+      ('short_name_false', ['-nob'], SystemExit),
+      ('short_name_double_dash', ['--b'], SystemExit),
+      ('short_name_double_dash_false', ['--nob'], SystemExit),
+  )
+  def test_parse_boolean_flags(self, args, expected):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    self.assertIsNone(self._absl_flags['absl_bool'].value)
+    self.assertIsNone(self._absl_flags['b'].value)
+    if isinstance(expected, bool):
+      parser.parse_args(args)
+      self.assertEqual(expected, self._absl_flags.absl_bool)
+      self.assertEqual(expected, self._absl_flags.b)
+    else:
+      with self.assertRaises(expected):
+        parser.parse_args(args)
+
+  @parameterized.named_parameters(
+      ('true', ['--notice'], True),
+      ('false', ['--nonotice'], False),
+  )
+  def test_parse_boolean_existing_no_prefix(self, args, expected):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    self.assertIsNone(self._absl_flags['notice'].value)
+    parser.parse_args(args)
+    self.assertEqual(expected, self._absl_flags.notice)
+
+  def test_unrecognized_flag(self):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    with self.assertRaises(SystemExit):
+      parser.parse_args(['--unknown_flag=what'])
+
+  def test_absl_validators(self):
+
+    @flags.validator('absl_integer', flag_values=self._absl_flags)
+    def ensure_positive(value):
+      return value > 0
+
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    with self.assertRaises(SystemExit):
+      parser.parse_args(['--absl_integer', '-2'])
+
+    del ensure_positive
+
+  @parameterized.named_parameters(
+      ('regular_name_double_dash', '--absl_string=new_string', 'new_string'),
+      ('regular_name_single_dash', '-absl_string=new_string', SystemExit),
+      ('short_name_double_dash', '--s=new_string', SystemExit),
+      ('short_name_single_dash', '-s=new_string', 'new_string'),
+  )
+  def test_dashes(self, argument, expected):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    if isinstance(expected, six.string_types):
+      parser.parse_args([argument])
+      self.assertEqual(self._absl_flags.absl_string, expected)
+    else:
+      with self.assertRaises(expected):
+        parser.parse_args([argument])
+
+  def test_absl_flags_not_added_to_namespace(self):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    args = parser.parse_args(['--absl_string=new_string'])
+    self.assertIsNone(getattr(args, 'absl_string', None))
+
+  def test_mixed_flags_and_positional(self):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    parser.add_argument('--header', help='Header message to print.')
+    parser.add_argument('integers', metavar='N', type=int, nargs='+',
+                        help='an integer for the accumulator')
+
+    args = parser.parse_args(
+        ['--absl_string=new_string', '--header=HEADER', '--absl_integer',
+         '2', '3', '4'])
+    self.assertEqual(self._absl_flags.absl_string, 'new_string')
+    self.assertEqual(self._absl_flags.absl_integer, 2)
+    self.assertEqual(args.header, 'HEADER')
+    self.assertListEqual(args.integers, [3, 4])
+
+  def test_subparsers(self):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    parser.add_argument('--header', help='Header message to print.')
+    subparsers = parser.add_subparsers(help='The command to execute.')
+
+    sub_parser = subparsers.add_parser(
+        'sub_cmd', help='Sub command.', inherited_absl_flags=self._absl_flags)
+    sub_parser.add_argument('--sub_flag', help='Sub command flag.')
+
+    def sub_command_func():
+      pass
+
+    sub_parser.set_defaults(command=sub_command_func)
+
+    args = parser.parse_args([
+        '--header=HEADER', '--absl_string=new_value', 'sub_cmd',
+        '--absl_integer=2', '--sub_flag=new_sub_flag_value'])
+
+    self.assertEqual(args.header, 'HEADER')
+    self.assertEqual(self._absl_flags.absl_string, 'new_value')
+    self.assertEqual(args.command, sub_command_func)
+    self.assertEqual(self._absl_flags.absl_integer, 2)
+    self.assertEqual(args.sub_flag, 'new_sub_flag_value')
+
+  def test_subparsers_no_inherit_in_subparser(self):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    subparsers = parser.add_subparsers(help='The command to execute.')
+
+    subparsers.add_parser(
+        'sub_cmd', help='Sub command.',
+        # Do not inherit absl flags in the subparser.
+        # This is the behavior that this test exercises.
+        inherited_absl_flags=None)
+
+    with self.assertRaises(SystemExit):
+      parser.parse_args(['sub_cmd', '--absl_string=new_value'])
+
+  def test_help_main_module_flags(self):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    help_message = parser.format_help()
+
+    # Only the short name is shown in the usage string.
+    self.assertIn('[-s ABSL_STRING]', help_message)
+    # Both names are included in the options section.
+    self.assertIn('-s ABSL_STRING, --absl_string ABSL_STRING', help_message)
+    # Verify help messages.
+    self.assertIn('help for --absl_string=%.', help_message)
+    self.assertIn('<apple|orange>: help for --absl_enum.', help_message)
+
+  def test_help_non_main_module_flags(self):
+    flags.DEFINE_string(
+        'non_main_module_flag', 'default', 'help',
+        module_name='other.module', flag_values=self._absl_flags)
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    help_message = parser.format_help()
+
+    # Non main module key flags are not printed in the help message.
+    self.assertNotIn('non_main_module_flag', help_message)
+
+  def test_help_non_main_module_key_flags(self):
+    flags.DEFINE_string(
+        'non_main_module_flag', 'default', 'help',
+        module_name='other.module', flag_values=self._absl_flags)
+    flags.declare_key_flag('non_main_module_flag', flag_values=self._absl_flags)
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    help_message = parser.format_help()
+
+    # Main module key fags are printed in the help message, even if the flag
+    # is defined in another module.
+    self.assertIn('non_main_module_flag', help_message)
+
+  @parameterized.named_parameters(
+      ('h', ['-h']),
+      ('help', ['--help']),
+      ('helpshort', ['--helpshort']),
+      ('helpfull', ['--helpfull']),
+  )
+  def test_help_flags(self, args):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    with self.assertRaises(SystemExit):
+      parser.parse_args(args)
+
+  @parameterized.named_parameters(
+      ('h', ['-h']),
+      ('help', ['--help']),
+      ('helpshort', ['--helpshort']),
+      ('helpfull', ['--helpfull']),
+  )
+  def test_no_help_flags(self, args):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags, add_help=False)
+    with mock.patch.object(parser, 'print_help'):
+      with self.assertRaises(SystemExit):
+        parser.parse_args(args)
+      parser.print_help.assert_not_called()
+
+  def test_helpfull_message(self):
+    flags.DEFINE_string(
+        'non_main_module_flag', 'default', 'help',
+        module_name='other.module', flag_values=self._absl_flags)
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    with self.assertRaises(SystemExit),\
+        mock.patch.object(sys, 'stdout', new=six.StringIO()) as mock_stdout:
+      parser.parse_args(['--helpfull'])
+    stdout_message = mock_stdout.getvalue()
+    logging.info('captured stdout message:\n%s', stdout_message)
+    self.assertIn('--non_main_module_flag', stdout_message)
+    self.assertIn('other.module', stdout_message)
+    # Make sure the main module is not included.
+    self.assertNotIn(sys.argv[0], stdout_message)
+    # Special flags defined in absl.flags.
+    self.assertIn('absl.flags:', stdout_message)
+    self.assertIn('--flagfile', stdout_message)
+    self.assertIn('--undefok', stdout_message)
+
+  @parameterized.named_parameters(
+      ('at_end',
+       ('1', '--absl_string=value_from_cmd', '--flagfile='),
+       'value_from_file'),
+      ('at_beginning',
+       ('--flagfile=', '1', '--absl_string=value_from_cmd'),
+       'value_from_cmd'),
+  )
+  def test_flagfile(self, cmd_args, expected_absl_string_value):
+    # Set gnu_getopt to False, to verify it's ignored by argparse_flags.
+    self._absl_flags.set_gnu_getopt(False)
+
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    parser.add_argument('--header', help='Header message to print.')
+    parser.add_argument('integers', metavar='N', type=int, nargs='+',
+                        help='an integer for the accumulator')
+    flagfile = tempfile.NamedTemporaryFile(dir=FLAGS.test_tmpdir, delete=False)
+    self.addCleanup(os.unlink, flagfile.name)
+    with flagfile:
+      flagfile.write(b'''
+# The flag file.
+--absl_string=value_from_file
+--absl_integer=1
+--header=header_from_file
+''')
+
+    expand_flagfile = lambda x: x + flagfile.name if x == '--flagfile=' else x
+    cmd_args = [expand_flagfile(x) for x in cmd_args]
+    args = parser.parse_args(cmd_args)
+
+    self.assertEqual([1], args.integers)
+    self.assertEqual('header_from_file', args.header)
+    self.assertEqual(expected_absl_string_value, self._absl_flags.absl_string)
+
+  @parameterized.parameters(
+      ('positional', {'positional'}, False),
+      ('--not_existed', {'existed'}, False),
+      ('--empty', set(), False),
+      ('-single_dash', {'single_dash'}, True),
+      ('--double_dash', {'double_dash'}, True),
+      ('--with_value=value', {'with_value'}, True),
+  )
+  def test_is_undefok(self, arg, undefok_names, is_undefok):
+    self.assertEqual(is_undefok, argparse_flags._is_undefok(arg, undefok_names))
+
+  @parameterized.named_parameters(
+      ('single', 'single', ['--single'], []),
+      ('multiple', 'first,second', ['--first', '--second'], []),
+      ('single_dash', 'dash', ['-dash'], []),
+      ('mixed_dash', 'mixed', ['-mixed', '--mixed'], []),
+      ('value', 'name', ['--name=value'], []),
+      ('boolean_positive', 'bool', ['--bool'], []),
+      ('boolean_negative', 'bool', ['--nobool'], []),
+      ('left_over', 'strip', ['--first', '--strip', '--last'],
+       ['--first', '--last']),
+  )
+  def test_strip_undefok_args(self, undefok, args, expected_args):
+    actual_args = argparse_flags._strip_undefok_args(undefok, args)
+    self.assertListEqual(expected_args, actual_args)
+
+  @parameterized.named_parameters(
+      ('at_end', ['--unknown', '--undefok=unknown']),
+      ('at_beginning', ['--undefok=unknown', '--unknown']),
+      ('multiple', ['--unknown', '--undefok=unknown,another_unknown']),
+      ('with_value', ['--unknown=value', '--undefok=unknown']),
+      ('maybe_boolean', ['--nounknown', '--undefok=unknown']),
+      ('with_space', ['--unknown', '--undefok', 'unknown']),
+  )
+  def test_undefok_flag_correct_use(self, cmd_args):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    args = parser.parse_args(cmd_args)  # Make sure it doesn't raise.
+    # Make sure `undefok` is not exposed in namespace.
+    sentinel = object()
+    self.assertIs(sentinel, getattr(args, 'undefok', sentinel))
+
+  def test_undefok_flag_existing(self):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    parser.parse_args(
+        ['--absl_string=new_value', '--undefok=absl_string'])
+    self.assertEqual('new_value', self._absl_flags.absl_string)
+
+  @parameterized.named_parameters(
+      ('no_equal', ['--unknown', 'value', '--undefok=unknown']),
+      ('single_dash', ['--unknown', '-undefok=unknown']),
+  )
+  def test_undefok_flag_incorrect_use(self, cmd_args):
+    parser = argparse_flags.ArgumentParser(
+        inherited_absl_flags=self._absl_flags)
+    with self.assertRaises(SystemExit):
+      parser.parse_args(cmd_args)
+
+
+class ArgparseWithAppRunTest(parameterized.TestCase):
+
+  @parameterized.named_parameters(
+      ('simple',
+       'main_simple', 'parse_flags_simple',
+       ['--argparse_echo=I am argparse.', '--absl_echo=I am absl.'],
+       ['I am argparse.', 'I am absl.']),
+      ('subcommand_roll_dice',
+       'main_subcommands', 'parse_flags_subcommands',
+       ['--argparse_echo=I am argparse.', '--absl_echo=I am absl.',
+        'roll_dice', '--num_faces=12'],
+       ['I am argparse.', 'I am absl.', 'Rolled a dice: ']),
+      ('subcommand_shuffle',
+       'main_subcommands', 'parse_flags_subcommands',
+       ['--argparse_echo=I am argparse.', '--absl_echo=I am absl.',
+        'shuffle', 'a', 'b', 'c'],
+       ['I am argparse.', 'I am absl.', 'Shuffled: ']),
+  )
+  def test_argparse_with_app_run(
+      self, main_func_name, flags_parser_func_name, args, output_strings):
+    env = os.environ.copy()
+    env['MAIN_FUNC'] = main_func_name
+    env['FLAGS_PARSER_FUNC'] = flags_parser_func_name
+    helper = 'absl/flags/tests/argparse_flags_test_helper'
+    try:
+      stdout = subprocess.check_output(
+          [_bazelize_command.get_executable_path(helper)] + args, env=env,
+          universal_newlines=True)
+    except subprocess.CalledProcessError as e:
+      error_info = ('ERROR: argparse_helper failed\n'
+                    'Command: {}\n'
+                    'Exit code: {}\n'
+                    '----- output -----\n{}'
+                    '------------------')
+      error_info = error_info.format(e.cmd, e.returncode,
+                                     e.output + '\n' if e.output else '<empty>')
+      print(error_info, file=sys.stderr)
+      raise
+
+    for output_string in output_strings:
+      self.assertIn(output_string, stdout)
+
+
+if __name__ == '__main__':
+  absltest.main()