Additional features

Schemathesis ships a set of optional features that could help to tune your tests.

Unique data generation

By default, Schemathesis may generate the same test cases as all data is randomized. If this behavior does not match your expectations, or your test budges, you can force Schemathesis to generate unique test cases.


$ st run --contrib-unique-data

In Python tests:

from schemathesis import contrib

# This is a global hook that will affect all the tests

Uniqueness is determined by the following parts of the generated data:

  • media_type

  • path_parameters

  • headers

  • cookies

  • query

  • body

UUID data for format: uuid in Open API

Open API 2.0 / 3.0 do not declare the uuid format as built-in, hence it is available as an extension:

from schemathesis.contrib.openapi import formats


You could also enable it via the --contrib-openapi-formats-uuid CLI option.


If you enable the OpenAPI 3.1 experimental feature, the UUID format support is automatically enabled. Refer to the Experimental Features section for more details.