flask.Flask.test_client¶

Flask.test_client(use_cookies=True, **kwargs)[source]¶

Creates a test client for this application. For information about unit testing head over to 1   Testing Flask Applications.

Note that if you are testing for assertions or exceptions in your application code, you must set app.testing = True in order for the exceptions to propagate to the test client. Otherwise, the exception will be handled by the application (not visible to the test client) and the only indication of an AssertionError or other exception will be a 500 status code response to the test client. See the testing attribute. For example:

app.testing = True
client = app.test_client()

The test client can be used in a with block to defer the closing down of the context until the end of the with block. This is useful if you want to access the context locals for testing:

with app.test_client() as c:
    rv = c.get('/?vodka=42')
    assert request.args['vodka'] == '42'

Additionally, you may pass optional keyword arguments that will then be passed to the application’s test_client_class constructor. For example:

from flask.testing import FlaskClient

class CustomClient(FlaskClient):
    def __init__(self, authentication=None, *args, **kwargs):
        FlaskClient.__init__(*args, **kwargs)
        self._authentication = authentication

app.test_client_class = CustomClient
client = app.test_client(authentication='Basic ....')

See FlaskClient for more information.

Changed in version 0.4: added support for with block usage for the client.

New in version 0.7: The use_cookies parameter was added as well as the ability to override the client to be used by setting the test_client_class attribute.

Changed in version 0.11: Added **kwargs to support passing additional keyword arguments to the constructor of test_client_class.