How to mock multiple dynamodb tables using moto - amazon-web-services

Question

I have a function create which uses 3 dynamodb tables. How do i mock three Dynamo db tables?
def create():
//This function uses a dynamodb table "x"
// Then it calls my_table() function
def my_table():
// This function basically uses two dynamodb table "y" and "z"
// This function returns a value which is used in create() function.
My test file has following code -
#patch.dict(os.environ, {"DYNAMODB_TABLE": "x",
'second_TABLE': "y",
'Third_TABLE': "z"
})
def test_create():
dynamodb_test()
event = { // my event values}
result = create(event)
assert result == 200
def dynamodb_test():
with mock_dynamodb2():
dynamodb = boto3.client('dynamodb', region_name='us-east-1')
dynamodb.create_table(
TableName=os.environ["DYNAMODB_TABLE"],
KeySchema=[
{
'AttributeName': 'id',
'KeyType': 'HASH'
}
],
AttributeDefinitions=[
{
'AttributeName': 'id',
'AttributeType': 'S'
}
],
ProvisionedThroughput={
'ReadCapacityUnits': 1,
'WriteCapacityUnits': 1
}
)
yield dynamodb
whenever i am testing test_create() function using pytest , i am getting
botocore.exceptions.ClientError: An error occurred (ExpiredTokenException) when
calling the Scan operation: The security token included in the request is expired
I think its trying to access the actual aws dynamo db but i want it to use mock dynamodb. How can i achieve this ?

Answer 1

Moto only works when two conditions are met:
The logic to be tested is executed inside a Moto-context
The Moto-context is started before any boto3-clients (or resources) are created
The Moto-context in your example, with mock_dynamodb2(), is localized to the dynamodb_test-function. After the function finishes, the mock is no longer active, and Boto3 will indeed try to access AWS itself.
Solution
The following test-function would satisfy both criteria:
#patch.dict(os.environ, {"DYNAMODB_TABLE": "x",
'second_TABLE': "y",
'Third_TABLE': "z"
})
# Initialize the mock here, so that it is effective for the entire test duration
#mock_dynamodb2
def test_create():
dynamodb_test()
event = { // my event values}
# Ensure that any boto3-clients/resources created in the logic are initialized while the mock is active
from ... import create
result = create(event)
assert result == 200
def dynamodb_test():
# There is no need to start the mock-context again here, so create the table immediately
dynamodb = boto3.client('dynamodb', region_name='us-east-1')
dynamodb.create_table(...)
The test code you provided does not talk about creating tables y and z - if the logic expects them to exist, you'd have to create them manually as well of course (just like table x was created in dynamodb_test.
Documentation for the import quirk can be found here: http://docs.getmoto.org/en/latest/docs/getting_started.html#recommended-usage

Answer 2

I believe this post is almost identical to yours. You could try this or utilize some of the other existing tools like localstack or dynamodb-local. The Python client for localstack for example: https://github.com/localstack/localstack-python-client
EDIT:
I see your title explains you want to use moto. I don't see you importing moto any of the moto modules into your code. See the last snippet in this page and replace s3 with either dynamodb, dynamodb2 (whichever you are using)