pytest-vcr

repository·master·Indexed 41 days ago

A pytest plugin for managing VCR.py cassettes. It records HTTP interactions during test execution and replays them in future runs to ensure tests are fast, deterministic, and independent of live external services. Features include the @pytest.mark.vcr marker for configuration, CLI options like --vcr-record and --disable-vcr, and fixtures for customizing cassette directories and filtering sensitive headers.

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What's inside pytest-vcr

Install pytest-vcr
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Install the pytest-vcr plugin using pip to enable VCR.py cassette management within your pytest suite.
```
pip install pytest-vcr
```
https://github.com/ktosiek/pytest-vcr/blob/master/README.rst
Run all tests and checks
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To execute the full suite of tests and automated checks for the project, use the tox command.
```
tox
```
https://github.com/ktosiek/pytest-vcr/blob/master/docs/hacking.md
Preview rendered documentation locally
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To view the rendered documentation in your browser while making changes, use tox to run the mkdocs environment with the --serve flag. This starts a local server at http://127.0.0.1:8000.
```
tox -e mkdocs -- serve
```
https://github.com/ktosiek/pytest-vcr/blob/master/docs/hacking.md
Run pytest-vcr on CI
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When running tests in a Continuous Integration (CI) environment, use the --vcr-record=none option. This ensures that tests only use existing cassettes and fail if a cassette is missing, preventing the CI from attempting to record new interactions and verifying that all necessary cassettes have been committed to the repository.
```
pytest --vcr-record=none
```
https://github.com/ktosiek/pytest-vcr/blob/master/docs/index.md
Generate combined test coverage reports
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When running tests via tox, coverage data is collected in parallel mode across different environments. To merge these results and generate a human-readable HTML report, run the following commands:
```
coverage combine && coverage html
```
https://github.com/ktosiek/pytest-vcr/blob/master/docs/hacking.md
Configure pytest-vcr using fixtures
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You can customize the VCR behavior by overriding specific pytest fixtures at the module scope:
- vcr_config: A dictionary containing additional arguments for the VCR constructor. Note that values here are overridden by marker options and command-line arguments.
- vcr_cassette_dir: The path to the directory where cassettes are stored. Defaults to test_file_directory + "/cassettes/".
- vcr_cassette_name: The name of the cassette for the current test. Defaults to the name of the test.
- vcr: The VCR instance used for creating cassettes. Override this to register custom matchers, serializers, or persisters.
```
@pytest.fixture(scope='module')
def vcr(vcr):
    vcr.register_matcher('my_matcher', my_matcher)
    vcr.match_on = ['my_matcher']  # This can also go into vcr_config or marker kwargs
    return vcr
```
https://github.com/ktosiek/pytest-vcr/blob/master/docs/configuration.md
Filter sensitive headers in cassettes
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To prevent secrets like API keys or passwords from being saved in your cassettes, use the vcr_config fixture to define filter_headers. This allows you to replace specific request/response headers with a placeholder value (e.g., DUMMY).
```
@pytest.fixture(scope='module')
def vcr_config():
    return {
        # Replace the Authorization request header with "DUMMY" in cassettes
        "filter_headers": [('authorization', 'DUMMY')],
    }
```
https://github.com/ktosiek/pytest-vcr/blob/master/docs/index.md
Use @pytest.mark.vcr to record and replay HTTP interactions
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To record HTTP interactions into a cassette, annotate your test function with the @pytest.mark.vcr() decorator.
On the first run, the plugin will execute the test and record the network interactions into a new YAML file located in a cassettes/ directory adjacent to your test file (e.g., cassettes/test_iana.yaml). On subsequent runs, the plugin will replay the recorded interactions from the cassette instead of making real network requests.
Note: You should commit the generated cassette files to your version control system (VCS).
```
@pytest.mark.vcr()
def test_iana():
    response = urlopen('http://www.iana.org/domains/reserved').read()
    assert b'Example domains' in response
```
https://github.com/ktosiek/pytest-vcr/blob/master/README.rst
Change the cassettes library path
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By default, pytest-vcr stores cassettes in a cassettes directory adjacent to the test file. You can override this behavior by providing a custom vcr_cassette_dir fixture. This is useful for organizing cassettes into a specific directory structure, such as vhs/{module}/{test}.yaml.
```
@pytest.fixture(scope='module')
def vcr_cassette_dir(request):
    # Put all cassettes in vhs/{module}/{test}.yaml
    return os.path.join('vhs', request.module.__name__)
```
https://github.com/ktosiek/pytest-vcr/blob/master/docs/index.md

Use the @pytest.mark.vcr marker

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The @pytest.mark.vcr marker allows you to pass configuration options directly to the VCR constructor for specific tests. Any keyword argument passed to the marker is treated as a VCR constructor argument.

Example usage:

@pytest.mark.vcr(ignore_localhost=True)
def test_local_and_remote():
    # This one will replay from the cassette
    urlopen('http://www.iana.org/domains/reserved').read()
    # This one will always be downloaded (because it is localhost)
    urlopen('http://127.0.0.1/').read()

@pytest.mark.vcr(ignore_localhost=True)
def test_local_and_remote():
    urlopen('http://www.iana.org/domains/reserved').read()
    urlopen('http://127.0.0.1/').read()

Configure pytest-vcr via command line options
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You can control VCR recording behavior directly from the CLI using the following flags:
- --vcr-record: Selects the VCR.py record mode. For example, use --vcr-record=none in CI environments to ensure tests only replay existing cassettes and do not attempt to make new network requests.
- --disable-vcr: Disables both replaying and recording. The VCR plugin remains installed but will not intercept or affect any network requests.
```
pytest --vcr-record=none
pytest --disable-vcr
```
https://github.com/ktosiek/pytest-vcr/blob/master/docs/configuration.md