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Integrates the Hoverfly HTTP proxy into Pytest

Project description

Pytest Hoverfly Wrapper

This pytest plugin allows easy integration of Hoverfly into your tests. Hoverfly is a proxy server that can intercept requests and return custom responses. More info on Hoverfly:


Clone the repository and then install using

python install

This will also automatically install the plugin's dependencies. Alternatively, install via pip:

pip install pytest-hoverfly-wrapper


The quickest way is to run tox:

pip install tox
tox -e <py35/py36/etc>

You can also run in pytest to make use of its debugging tools: (Assumes you have a virtual environment set up for a compatible Python version - see for compatible versions)

python install
pip install -r requirements-test.txt
pytest tests/

end_to_end tests the plugin's integration with a Pytest framework: each test consists of a pytest script that gets fed into pytester and run inside a virtual Pytest environment. The result of that is asserted against. The reason we need this is to test failure modes, which would cause the test to fail.

unit contains tests for individual functions.

Usage example

Cache responses to external services

Adding the setup_hoverfly fixture will stand up a Hoverfly server instance running on port 8500. You can then use this as a proxy that saves the responses to any requests make via the proxy. If the test passes, the saved responses will be dumped to file, which will be used when the test runs again.

# Enable the fixture explicitly in your tests or (not required when using setuptools entry points)
from pytest_hoverfly_wrapper import GeneratedSimulation
import requests
import pytest

def test_something(setup_hoverfly):
    proxy_port = setup_hoverfly[1]
    proxies = {
     "http": "http://localhost:{}".format(proxy_port),
     "https": "http://localhost:{}".format(proxy_port),
    requests.get("", proxies=proxies)

After running the test for the first time, you will find a file located at ./test_data/generated/some_file.json, containing all the requests made using the proxy, as well as the responses to them. Upon running the test the second time, the test will load the file and attempt to match requests to the list in the file. If a successful match is found, the matching response will be served. If not, the request will be made to its original target and the target's response will be served instead.

Completely fake responses

You can also specify your own custom responses.

# Enable the fixture explicitly in your tests or (not required when using setuptools entry points)
from pytest_hoverfly_wrapper import StaticSimulation
import requests
import pytest

def test_something(setup_hoverfly):
    proxy_port = setup_hoverfly[1]
    proxies = {
     "http": "http://localhost:{}".format(proxy_port),
     "https": "http://localhost:{}".format(proxy_port),
    r = requests.get("", proxies=proxies)
    assert r.status_code == 404

Full code is in sample/

Hoverfly crashes

Occasionally, the Hoverfly proxy might crash mid-test. If this happens, the test will raise HoverflyCrashException, which gives you clarity of why the test failed and can be caught in your testing framework as part of some test retrying logic.


pytest-hoverfly-wrapper uses the in-built logging module for logs. To import the logger:

import logging
from pytest_hoverfly_wrapper import LOGGER_NAME
hoverfly_logger = logging.getLogger(LOGGER_NAME)

Then customise the logger as necessary.


In all scenarios, when a response is sent by Hoverfly rather than a remote server, that response will have the Hoverfly-Cache-Served header set. This differentiates the two types of response, and helps debug situations where you think a response is being served by Hoverfly but isn't, e.g. when Hoverfly fails to match the request even though you're expecting it to.

At the end of the test, the plugin will create a network.json file containing the list of all requests made (and responses received) during the test, including parameters and headers.

Release History

  • 0.1.0
    • Initial release
  • 0.1.1
    • Updates the description in the PyPi page.
  • 0.1.2
    • Create test data directory if it doesn't exist
  • 0.1.3
    • Put the bugfix in 0.1.2 in its correct place and remove extraneous code
  • 0.1.4
    • Fixes broken domain blocking functionality
  • 0.2.0
    • Bug fixes and command line option to pass custom parameters to Hoverfly executable command
  • 0.3.0
    • Expose Journal API for accessing journal
  • 0.3.2
    • Fixes bug where block_domains is ignored if a simulation file isn't specified in StaticSimulation
  • 0.3.3
    • Registers simulated marker used by plugin
  • 0.4.0
    • Strips Expires property from Set-Cookie headers in recorded simulations
  • 0.4.1
    • Fixes typo in installation instructions
  • 0.5.0
    • Records simulations for static simulations if they don't exist yet
  • 0.5.1
    • Clean up of code styling, docs and tests.
  • 1.0.0
    • Automatic download of binaries; support for <3.7 dropped; support added for Windows
  • 1.0.1
    • Fix classifiers, and pull in latest Hoverfly version always


For all queries contact Veli Akiner:

Distributed under a modified MIT license. See LICENSE for more information.


  1. Fork it (
  2. Create your feature branch (git checkout -b feature/fooBar)
  3. Commit your changes (git commit -am 'Add some fooBar')
  4. Push to the branch (git push origin feature/fooBar)
  5. Create a new Pull Request

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