Added a test that queries an index when created via the table resource update

When you create an index via the table resource update, in python 3.6, it is saved as a `dict_value`,
which causes an error - this test replicates this bug

tests/test_dynamodb2/test_dynamodb.py

@@ -1,16 +1,17 @@
 from __future__ import unicode_literals, print_function
 
+from decimal import Decimal
+
 import six
 import boto
 import boto3
-from boto3.dynamodb.conditions import Attr
+from boto3.dynamodb.conditions import Attr, Key
 import sure  # noqa
 import requests
 from moto import mock_dynamodb2, mock_dynamodb2_deprecated
 from moto.dynamodb2 import dynamodb_backend2
 from boto.exception import JSONResponseError
 from botocore.exceptions import ClientError
-from boto3.dynamodb.conditions import Key
 from tests.helpers import requires_boto_gte
 import tests.backport_assert_raises
 
@@ -1199,3 +1200,95 @@ def test_update_if_not_exists():
     resp = table.scan()
     # Still the original value
     assert resp['Items'][0]['created_at'] == 123
+
+
+@mock_dynamodb2
+def test_query_global_secondary_index_when_created_via_update_table_resource():
+    dynamodb = boto3.resource('dynamodb', region_name='us-east-1')
+
+    # Create the DynamoDB table.
+    dynamodb.create_table(
+        TableName='users',
+        KeySchema=[
+            {
+                'AttributeName': 'user_id',
+                'KeyType': 'HASH'
+            },
+        ],
+        AttributeDefinitions=[
+            {
+                'AttributeName': 'user_id',
+                'AttributeType': 'N',
+            },
+            {
+                'AttributeName': 'forum_name',
+                'AttributeType': 'S'
+            },
+            {
+                'AttributeName': 'subject',
+                'AttributeType': 'S'
+            },
+        ],
+        ProvisionedThroughput={
+            'ReadCapacityUnits': 5,
+            'WriteCapacityUnits': 5
+        },
+    )
+    table = dynamodb.Table('users')
+    table.update(
+        AttributeDefinitions=[
+            {
+                'AttributeName': 'forum_name',
+                'AttributeType': 'S'
+            },
+        ],
+        GlobalSecondaryIndexUpdates=[
+            {'Create':
+                {
+                    'IndexName': 'forum_name_index',
+                    'KeySchema': [
+                        {
+                            'AttributeName': 'forum_name',
+                            'KeyType': 'HASH',
+                        },
+                    ],
+                    'Projection': {
+                        'ProjectionType': 'ALL',
+                    },
+                    'ProvisionedThroughput': {
+                        'ReadCapacityUnits': 5,
+                        'WriteCapacityUnits': 5
+                    },
+                }
+            }
+        ]
+    )
+
+    next_user_id = 1
+    for my_forum_name in ['cats', 'dogs']:
+        for my_subject in ['my pet is the cutest', 'wow look at what my pet did', "don't you love my pet?"]:
+            table.put_item(Item={'user_id': next_user_id, 'forum_name': my_forum_name, 'subject': my_subject})
+            next_user_id += 1
+
+    # get all the cat users
+    forum_only_query_response = table.query(
+        IndexName='forum_name_index',
+        Select='ALL_ATTRIBUTES',
+        KeyConditionExpression=Key('forum_name').eq('cats'),
+    )
+    forum_only_items = forum_only_query_response['Items']
+    assert len(forum_only_items) == 3
+    for item in forum_only_items:
+        assert item['forum_name'] == 'cats'
+
+    # query all cat users with a particular subject
+    forum_and_subject_query_results = table.query(
+        IndexName='forum_name_index',
+        Select='ALL_ATTRIBUTES',
+        KeyConditionExpression=Key('forum_name').eq('cats'),
+        FilterExpression=Attr('subject').eq('my pet is the cutest'),
+    )
+    forum_and_subject_items = forum_and_subject_query_results['Items']
+    assert len(forum_and_subject_items) == 1
+    assert forum_and_subject_items[0] == {'user_id': Decimal('1'), 'forum_name': 'cats',
+                                          'subject': 'my pet is the cutest'}