Moto - Mock Boto

In a nutshell

Moto is a library that allows your python tests to easily mock out the boto library.

Imagine you have the following code that you want to test:

importbotofromboto.s3.keyimportKeyclassMyModel(object):
def__init__(self, name, value):
self.name=nameself.value=valuedefsave(self):
conn=boto.connect_s3()
bucket=conn.get_bucket('mybucket')
k=Key(bucket)
k.key=self.namek.set_contents_from_string(self.value)

Take a minute to think how you would have tested that in the past.

Now see how you could test it with Moto:

importbotofrommotoimportmock_s3frommymoduleimportMyModel@mock_s3deftest_my_model_save():
conn=boto.connect_s3()
# We need to create the bucket since this is all in Moto's 'virtual' AWS accountconn.create_bucket('mybucket')
model_instance=MyModel('steve', 'is awesome')
model_instance.save()
assertconn.get_bucket('mybucket').get_key('steve').get_contents_as_string() =='is awesome'

With the decorator wrapping the test, all the calls to s3 are automatically mocked out. The mock keeps the state of the buckets and keys.

It gets even better! Moto isn't just S3. Here's the status of the other AWS services implemented.

|------------------------------------------------------------------------------|| ServiceName | Decorator | DevelopmentStatus ||------------------------------------------------------------------------------|| Autoscaling | @mock_autoscaling| coreendpointsdone ||------------------------------------------------------------------------------|| Cloudformation | @mock_cloudformation| coreendpointsdone ||------------------------------------------------------------------------------|| Cloudwatch | @mock_cloudwatch | basicendpointsdone ||------------------------------------------------------------------------------|| DataPipeline | @mock_datapipeline| basicendpointsdone ||------------------------------------------------------------------------------|| DynamoDB | @mock_dynamodb | coreendpointsdone || DynamoDB2 | @mock_dynamodb2 | coreendpointsdone - noindexes ||------------------------------------------------------------------------------|| EC2 | @mock_ec2 | coreendpointsdone || - AMI | | coreendpointsdone || - EBS | | coreendpointsdone || - Instances | | allendpointsdone || - SecurityGroups | | coreendpointsdone || - Tags | | allendpointsdone ||------------------------------------------------------------------------------|| ELB | @mock_elb | coreendpointsdone ||------------------------------------------------------------------------------|| EMR | @mock_emr | coreendpointsdone ||------------------------------------------------------------------------------|| Glacier | @mock_glacier | coreendpointsdone ||------------------------------------------------------------------------------|| IAM | @mock_iam | coreendpointsdone ||------------------------------------------------------------------------------|| Kinesis | @mock_kinesis | coreendpointsdone ||------------------------------------------------------------------------------|| RDS | @mock_rds | coreendpointsdone ||------------------------------------------------------------------------------|| RDS2 | @mock_rds2 | coreendpointsdone ||------------------------------------------------------------------------------|| Redshift | @mock_redshift | coreendpointsdone ||------------------------------------------------------------------------------|| Route53 | @mock_route53 | coreendpointsdone ||------------------------------------------------------------------------------|| S3 | @mock_s3 | coreendpointsdone ||------------------------------------------------------------------------------|| SES | @mock_ses | coreendpointsdone ||------------------------------------------------------------------------------|| SNS | @mock_sns | coreendpointsdone ||------------------------------------------------------------------------------|| SQS | @mock_sqs | coreendpointsdone ||------------------------------------------------------------------------------|| STS | @mock_sts | coreendpointsdone ||------------------------------------------------------------------------------|

Another Example

Imagine you have a function that you use to launch new ec2 instances:

importbotodefadd_servers(ami_id, count):
conn=boto.connect_ec2('the_key', 'the_secret')
forindexinrange(count):
conn.run_instances(ami_id)

To test it:

from . importadd_servers@mock_ec2deftest_add_servers():
add_servers('ami-1234abcd', 2)
conn=boto.connect_ec2('the_key', 'the_secret')
reservations=conn.get_all_instances()
assertlen(reservations) ==2instance1=reservations[0].instances[0]
assertinstance1.image_id=='ami-1234abcd'

Usage

All of the services can be used as a decorator, context manager, or in a raw form.

Decorator

@mock_s3deftest_my_model_save():
conn=boto.connect_s3()
conn.create_bucket('mybucket')
model_instance=MyModel('steve', 'is awesome')
model_instance.save()
assertconn.get_bucket('mybucket').get_key('steve').get_contents_as_string() =='is awesome'

Context Manager

deftest_my_model_save():
withmock_s3():
conn=boto.connect_s3()
conn.create_bucket('mybucket')
model_instance=MyModel('steve', 'is awesome')
model_instance.save()
assertconn.get_bucket('mybucket').get_key('steve').get_contents_as_string() =='is awesome'

Raw use

deftest_my_model_save():
mock=mock_s3()
mock.start()
conn=boto.connect_s3()
conn.create_bucket('mybucket')
model_instance=MyModel('steve', 'is awesome')
model_instance.save()
assertconn.get_bucket('mybucket').get_key('steve').get_contents_as_string() =='is awesome'mock.stop()

Stand-alone Server Mode

Moto also comes with a stand-alone server mode. This allows you to utilize the backend structure of Moto even if you don't use Python.

To run a service:

$ moto_server ec2 * Running on http://0.0.0.0:5000/

You can also pass the port as the second argument:

$ moto_server ec2 -p3000 * Running on http://0.0.0.0:3000/

Then go to localhost to see a list of running instances (it will be empty since you haven't added any yet).

If you want to use boto with this (using the simpler decorators above instead is strongly encouraged), the easiest way is to create a boto config file (~/.boto) with the following values:

[Boto]
is_secure = False
https_validate_certificates = False
proxy_port = 5000
proxy = 127.0.0.1

Install

$ pip install moto

Thanks

A huge thanks to Gabriel Falcão and his HTTPretty library. Moto would not exist without it.