Remove oauth2client._helpers dependency (#493)

diff --git a/tests/test__helpers.py b/tests/test__helpers.py
new file mode 100644
index 0000000..e33ea71
--- /dev/null
+++ b/tests/test__helpers.py
@@ -0,0 +1,161 @@
+# Copyright 2015 Google Inc. All rights reserved.
+#
+# 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.
+
+"""Unit tests for googleapiclient._helpers."""
+
+import unittest
+
+import mock
+
+import six
+from six.moves import urllib
+
+from googleapiclient import _helpers
+
+
+class PositionalTests(unittest.TestCase):
+
+    def test_usage(self):
+        _helpers.positional_parameters_enforcement = (
+            _helpers.POSITIONAL_EXCEPTION)
+
+        # 1 positional arg, 1 keyword-only arg.
+        @_helpers.positional(1)
+        def function(pos, kwonly=None):
+            return True
+
+        self.assertTrue(function(1))
+        self.assertTrue(function(1, kwonly=2))
+        with self.assertRaises(TypeError):
+            function(1, 2)
+
+        # No positional, but a required keyword arg.
+        @_helpers.positional(0)
+        def function2(required_kw):
+            return True
+
+        self.assertTrue(function2(required_kw=1))
+        with self.assertRaises(TypeError):
+            function2(1)
+
+        # Unspecified positional, should automatically figure out 1 positional
+        # 1 keyword-only (same as first case above).
+        @_helpers.positional
+        def function3(pos, kwonly=None):
+            return True
+
+        self.assertTrue(function3(1))
+        self.assertTrue(function3(1, kwonly=2))
+        with self.assertRaises(TypeError):
+            function3(1, 2)
+
+    @mock.patch('googleapiclient._helpers.logger')
+    def test_enforcement_warning(self, mock_logger):
+        _helpers.positional_parameters_enforcement = (
+            _helpers.POSITIONAL_WARNING)
+
+        @_helpers.positional(1)
+        def function(pos, kwonly=None):
+            return True
+
+        self.assertTrue(function(1, 2))
+        self.assertTrue(mock_logger.warning.called)
+
+    @mock.patch('googleapiclient._helpers.logger')
+    def test_enforcement_ignore(self, mock_logger):
+        _helpers.positional_parameters_enforcement = _helpers.POSITIONAL_IGNORE
+
+        @_helpers.positional(1)
+        def function(pos, kwonly=None):
+            return True
+
+        self.assertTrue(function(1, 2))
+        self.assertFalse(mock_logger.warning.called)
+
+
+class AddQueryParameterTests(unittest.TestCase):
+
+    def test__add_query_parameter(self):
+        self.assertEqual(
+            _helpers._add_query_parameter('/action', 'a', None),
+            '/action')
+        self.assertEqual(
+            _helpers._add_query_parameter('/action', 'a', 'b'),
+            '/action?a=b')
+        self.assertEqual(
+            _helpers._add_query_parameter('/action?a=b', 'a', 'c'),
+            '/action?a=c')
+        # Order is non-deterministic.
+        self.assertIn(
+            _helpers._add_query_parameter('/action?a=b', 'c', 'd'),
+            ['/action?a=b&c=d', '/action?c=d&a=b'])
+        self.assertEqual(
+            _helpers._add_query_parameter('/action', 'a', ' ='),
+            '/action?a=+%3D')
+
+
+def assertUrisEqual(testcase, expected, actual):
+    """Test that URIs are the same, up to reordering of query parameters."""
+    expected = urllib.parse.urlparse(expected)
+    actual = urllib.parse.urlparse(actual)
+    testcase.assertEqual(expected.scheme, actual.scheme)
+    testcase.assertEqual(expected.netloc, actual.netloc)
+    testcase.assertEqual(expected.path, actual.path)
+    testcase.assertEqual(expected.params, actual.params)
+    testcase.assertEqual(expected.fragment, actual.fragment)
+    expected_query = urllib.parse.parse_qs(expected.query)
+    actual_query = urllib.parse.parse_qs(actual.query)
+    for name in expected_query.keys():
+        testcase.assertEqual(expected_query[name], actual_query[name])
+    for name in actual_query.keys():
+        testcase.assertEqual(expected_query[name], actual_query[name])
+
+
+class Test_update_query_params(unittest.TestCase):
+
+    def test_update_query_params_no_params(self):
+        uri = 'http://www.google.com'
+        updated = _helpers.update_query_params(uri, {'a': 'b'})
+        self.assertEqual(updated, uri + '?a=b')
+
+    def test_update_query_params_existing_params(self):
+        uri = 'http://www.google.com?x=y'
+        updated = _helpers.update_query_params(uri, {'a': 'b', 'c': 'd&'})
+        hardcoded_update = uri + '&a=b&c=d%26'
+        assertUrisEqual(self, updated, hardcoded_update)
+
+    def test_update_query_params_replace_param(self):
+        base_uri = 'http://www.google.com'
+        uri = base_uri + '?x=a'
+        updated = _helpers.update_query_params(uri, {'x': 'b', 'y': 'c'})
+        hardcoded_update = base_uri + '?x=b&y=c'
+        assertUrisEqual(self, updated, hardcoded_update)
+
+    def test_update_query_params_repeated_params(self):
+        uri = 'http://www.google.com?x=a&x=b'
+        with self.assertRaises(ValueError):
+            _helpers.update_query_params(uri, {'a': 'c'})
+
+
+class Test_parse_unique_urlencoded(unittest.TestCase):
+
+    def test_without_repeats(self):
+        content = 'a=b&c=d'
+        result = _helpers.parse_unique_urlencoded(content)
+        self.assertEqual(result, {'a': 'b', 'c': 'd'})
+
+    def test_with_repeats(self):
+        content = 'a=b&a=d'
+        with self.assertRaises(ValueError):
+            _helpers.parse_unique_urlencoded(content)