Easier API testing

Tavern is a pytest plugin, command-line tool and Python library for automated testing of APIs, with a simple, concise and flexible YAML-based syntax. It’s very simple to get started, and highly customisable for complex tests. Tavern supports testing RESTful APIs as well as MQTT based APIs.

Tavern acts as a pytest plugin so that all you have to do is install pytest and Tavern, write your tests in .tavern.yaml files, and run pytest. This means you get access to all of the pytest ecosystem.

You can also integrate Tavern into your own test framework or continuous integration setup using the Python library, or use the command line tool, tavern-ci with bash scripts and cron jobs.

Quickstart

First up run pip install tavern.

Then, let’s create a basic test, test_minimal.tavern.yaml:

---
# Every test file has one or more tests...
test_name: Get some fake data from the JSON placeholder API

# ...and each test has one or more stages (e.g. an HTTP request)
stages:
  - name: Make sure we have the right ID

    # Define the request to be made...
    request:
      url: https://jsonplaceholder.typicode.com/posts/1
      method: GET

    # ...and the expected response code and body
    response:
      status_code: 200
      # A JSON dict response
      json:
        id: 1

This file can have any name, but if you intend to use Pytest with Tavern, it will only pick up files called test_*.tavern.yaml.

This can then be run like so:

$ pip install tavern[pytest]
$ py.test test_minimal.tavern.yaml  -v
=================================== test session starts ===================================
platform linux -- Python 3.5.2, pytest-3.4.2, py-1.5.2, pluggy-0.6.0 -- /home/taverntester/.virtualenvs/tavernexample/bin/python3
cachedir: .pytest_cache
rootdir: /home/taverntester/myproject, inifile:
plugins: tavern-0.7.2
collected 1 item

test_minimal.tavern.yaml::Get some fake data from the JSON placeholder API PASSED   [100%]

================================ 1 passed in 0.14 seconds =================================

Tavern is not just limited to testing HTTP APIs however - it can also be used to test MQTT, or you can mix MQTT commands inline with HTTP tests to test more complex systems.

To learn more, check out the examples or the complete documentation. If you’re interested in contributing to the project take a look at the GitHub repo.

Why not Postman, Insomnia or pyresttest etc?

Tavern is a focused tool which does one thing well: automated testing of APIs.

Postman and Insomnia are excellent tools which cover a wide range of use-cases for RESTful APIs, and indeed we use Tavern alongside Postman. However, specifically with regards to automated testing, Tavern has several advantages over Postman:

• A full-featured Python environment for writing easily reusable custom validation functions
• Testing of MQTT based systems in tandem with RESTful APIS.
• Seamless integration with pytest to keep all your tests in one place
• A simpler, less verbose and clearer testing language

Tavern does not do many of the things Postman and Insomnia do. For example, Tavern does not have a GUI nor does it do API monitoring or mock servers. On the other hand, Tavern is free and open-source and is a more powerful tool for developers to automate tests.

pyresttest is a similar tool to Tavern for testing RESTful APIs, but is no longer actively developed. On top of MQTT testing, Tavern has several other advantages over PyRestTest which overall add up to a better developer experience:

• Cleaner test syntax which is more intuitive, especially for non-developers
• Validation function are more flexible and easier to use
• Better explanations of why a test failed

Questions and community

If you have any feature requests or if you’ve found a bug you can raise an issue on GitHub.

We also have a Gitter chat for questions and general conversation about the use and development of Tavern.