Default recording mode

pytest-recording uses the none VCR recording mode by default to prevent unintentional network requests. To allow them you need to pass a different recording mode (e.g. once) via the --record-mode CLI option to your test command. See more information about available recording modes in the official VCR documentation

Configuration

You can provide the recording configuration with the vcr_config fixture, which could be any scope - session, package, module, or function. It should return a dictionary that will be passed directly to VCR.use_cassettes under the hood.

import pytest

@pytest.fixture(scope="module")
def vcr_config():
    return {"filter_headers": ["authorization"]}

For more granular control you need to pass these keyword arguments to individual pytest.mark.vcr marks, and in this case all arguments will be merged into a single dictionary with the following priority (low -> high):

• vcr_config fixture

• all marks from the most broad scope (“session”) to the most narrow one (“function”)

Example:

import pytest

pytestmark = [pytest.mark.vcr(ignore_localhost=True)]

@pytest.fixture(scope="module")
def vcr_config():
    return {"filter_headers": ["authorization"]}

@pytest.mark.vcr(filter_headers=[])
def test_one():
    ...

@pytest.mark.vcr(filter_query_parameters=["api_key"])
def test_two():
    ...

Resulting VCR configs for each test:

• test_one - {"ignore_localhost": True, "filter_headers": []}

• test_two - {"ignore_localhost": True, "filter_headers": ["authorization"], "filter_query_parameters": ["api_key"]}

The vcr_config fixture forwards any keyword argument to vcrpy, so ignore_hosts and other VCR.py options work directly:

import pytest

@pytest.fixture(scope="module")
def vcr_config():
    return {
        "filter_headers": ["authorization"],
        "ignore_hosts": ["169.254.169.254", "metadata.google.internal"],
    }

You can get access to the used VCR instance via pytest_recording_configure hook. It might be useful for registering custom matchers, persisters, etc.:

# conftest.py

def jurassic_matcher(r1, r2):
    assert r1.uri == r2.uri and "JURASSIC PARK" in r1.body, \
        "required string (JURASSIC PARK) not found in request body"

def pytest_recording_configure(config, vcr):
    vcr.register_matcher("jurassic", jurassic_matcher)

You can disable the VCR.py integration entirely by passing the --disable-recording CLI option.

Rewrite record mode

It is possible to rewrite a cassette from scratch and not extend it with new entries as it works now with the all record mode from VCR.py.

However, it will rewrite only the default cassette and won’t touch extra cassettes.

import pytest

@pytest.fixture(scope="module")
def vcr_config():
    return {"record_mode": "rewrite"}

Or via command-line option:

$ pytest --record-mode=rewrite tests/

Blocking network access

To have more confidence that your tests will not go over the wire, you can block it with pytest.mark.block_network mark:

import pytest
import requests

@pytest.mark.block_network
def test_multiple():
    assert requests.get("http://httpbin.org/get").text == '{"get": true}'

...
# in case of access
RuntimeError: Network is disabled

Besides marks, the network access could be blocked globally with --block-network command-line option.

However, if VCR.py recording is enabled, the network is not blocked for tests with pytest.mark.vcr.

Example:

import pytest
import requests

@pytest.mark.vcr
def test_multiple():
    assert requests.get("http://httpbin.org/get").text == '{"get": true}'

Run pytest:

$ pytest --record-mode=once --block-network tests/

The network blocking feature supports socket-based transports and pycurl.

It is possible to allow access to specified hosts during network blocking:

import pytest
import requests

@pytest.mark.block_network(allowed_hosts=["httpbin.*"])
def test_access():
    assert requests.get("http://httpbin.org/get").text == '{"get": true}'
    with pytest.raises(RuntimeError, match=r"^Network is disabled$"):
        requests.get("http://example.com")

Or via command-line option:

$ pytest --record-mode=once --block-network --allowed-hosts=httpbin.*,localhost tests/

Or via vcr_config fixture:

import pytest

@pytest.fixture(autouse=True)
def vcr_config():
    return {"allowed_hosts": ["httpbin.*"]}