Skip to main content

Fake servers for testing

Project description

An Introduction to Pretenders

The pretenders project creates flexible fakes for external network services. These external services can be faked by setting pre-canned answers, defining expectations, or just querying them on received data after [test] execution.

They are loosely designed along the pattern of Record/Replay/Verify.

Python Compatibility

The server side of Pretenders is written in Python3:

  • Because we firmly believe all new projects should use Python3, unless there are very compelling reasons against it.

  • Because since these will be run as standalone servers, compatibility is not such an issue

In the cases we implement a client, we will be making this runnable in Python 3.x and Python 2.6/2.7.

Mocked Servers Available

Pretenders currently supports the mocking of HTTP and SMTP servers.

Future services we are considering to support include AMQP and ssh.

These represent the vast majority of the services that the software we write interacts with.

Some example use cases include:

  • Mocking external HTTP-based APIs at the wire level in module integration tests

  • Facilitating the manual testing and debugging of front-end Ajax code where the back-end has not been developed yet

  • Writing fully automated tests for any system that sends email, and where we want to easily verify outgoing mails

Pretenders provides a unified RESTful API to verify the interactions of our code with external services, regardless of the service protocol.

pretenders.client.http - HTTP server

Typical usage is to mock RESTful/SOAP APIs of external services.

This will normally require pre-programming the service with responses, and enquiring the service later about received requests. This can be done with specialised assertions / matchers, or by setting expectations and verifying fulfilment of such expectations.

The pre-programming step may be done by using specific proprietary HTTP headers, or by using an alternative HTTP port to the one used for mocking.

For example usage see the documentation.

Implementation is based on the bottle web microframework.

One of our goals will be that the wire protocol is simple enough that you do not need any specialised client. That said, we will be providing client libraries (at least one in Python) to simplify interacting with the server, and to provide a comfortable API to use in tests.


You can run pretenders from its official docker image:

docker run -d --name pretenders -p <desired_port>:8000 pretenders/pretenders:1.4

Getting Help

For discussions about the usage, development, and future of pretenders, please join the pretenders mailing list.


Full documentation of the project can be found here:


Pretenders welcomes contributions in any form - be it pull requests, adding an issue or feedback via github or sending a message on the pretenders mailing list so don’t be shy!

We have the following branching convention:

  • master: This should look exactly like the latest release.

  • develop: This is where ongoing work lands, only being merged into master at release point.

In order to contribute, fork the repo in github and branch from the develop branch. Create your PRs into develop in the main repo.

Running the tests runs the full suite of tests, as well as building the sphinx docs and checking for pep8 errors.

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

pretenders-1.4.5.tar.gz (427.6 kB view hashes)

Uploaded source

Built Distribution

pretenders-1.4.5-py3-none-any.whl (443.2 kB view hashes)

Uploaded py3

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page