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Introduction

snowflake-vcrpy is a library that allows you to record and replay HTTP interactions initiated by snowflake-connector-python for testing purposes. It is a pytest plugin built upon VCR.py. Libraries like snowpark-python and snowflake-sqlalchemy depending on the connector for HTTP interactions can also leverage the library.

snowflake-vcrpy provides the following features:

  1. pytest fixtures to enable record and replay HTTP-based tests
  2. pytest options to select the tests run in record-and-replay mode

Installation

snowflake-vcrpy can be installed from source code:

$ git clone [email protected]:Snowflake-Labs/snowflake-vcrpy.git
$ cd snowflake-vcrpy
$ pip install .

Quick Start

Annotate a test with pytest marker to run in record-and-replay mode

# Annotate the test to run in record-and-replay mode
import snowflake.connector
@pytest.mark.snowflake_vcr
def test_method():
    CONNECTION_PARAMETERS = {} # snowflake credentials
    with snowflake.connector.connect(**CONNECTION_PARAMETERS) as conn, conn.cursor() as cursor:
        assert cursor.execute('select 1').fetchall() == [(1,)]

Run with pytest

As a pytest plugin, snowflake-vcrpy by default will identify tests annotated with @pytest.mark.snowflake_vcr and run those tests in record-and-replay mode.

$pytest <test_file.py>

Rationale

snowflake-vcrpy incorporated VCR.py to achieve recording and replaying.

The first time the test is run, a recording file consisting of HTTP requests and responses, will be generated under the directory <your_test_folder>/cassettes with the naming convention of <test_class_name>.<test_method_name>.yaml.

VCR.py will retrieve the serialized requests and responses stored in the cassette file, and if it recognizes any HTTP requests from the original test run, it will intercept them and return the corresponding recorded responses.

To accommodate any changes made to the API of the server being tested or responses, simply remove the existing cassette files and rerun your tests. VCR.py will identify the missing cassette files and automatically record all HTTP interactions.

For advanced topics such as how request matching works or what options VCR.py provides, please refer to the VCP.py documentation. To configure VCR.py within snowflake-vcrpy, please refer to section Optional vcrpy configuration.

pytest options to run tests in record-and-replay mode

Specifying tests

A pytest option is provided to select the tests run in record and replay mode: --snowflake-record-tests-selectio and there are three modes annotated, disable, all:

  • annotated: This is the default mode, pytest will only run the tests annotated with @pytest.mark.snowflake_vcr in record and replay mode.
  • disable: This will disable record and replay for all tests.
  • all This will all tests in record and replay regardless of whether the test is annotated with @pytest.mark.snowflake_vcr.
# run tests which are annotated with `@pytest.mark.snowflake_vcr` in record and replay, this is the default mode
$ pytest <tests>
# run tests which are annotated with `@pytest.mark.snowflake_vcr` in record and replay, with explicitly setting the default mode
$ pytest <tests> --snowflake-record-tests-selection annotated
# disable running record and replay mode for all the tests
$ pytest <tests> --snowflake-record-tests-selection disable
# run all the tests in record and replay regardless of whether the tests are being annotated with `@pytest.mark.snowflake_vcr`
$ pytest <tests> --snowflake-record-tests-selection all

Optional vcrpy configuration

Customized vcrpy config per test case

vcr_config = {
    'path': '<path_to_recording>'
    # for more configs please refer to: https://vcrpy.readthedocs.io/en/latest/configuration.html
}
@pytest.mark.snowflake_vcr(**vcr_config)
def test_method_passing_vcr_config():
    pass

Global pytest fixture

snowflake-vcrpy pytest plugin will read the pytest fixture snowflake_vcr_config to create module-scope VCR instance. If configs are also provided through pytest marker kwargs, then the global fixture configs will be overridden.

@pytest.fixture(scope="module")
def snowflake_vcr_config():
    return {
        # your vcr config dict
    }