Test data

Faker integration — fake_email / fake_name / fake_value and friends; faker is a soft dependency.
Factories — Factory(defaults) evaluates callable defaults per build(); pre-built user_factory / order_factory / product_factory.
Testcontainers — start_postgres / start_redis / start_generic wrap testcontainers-python.
.env loader + ${ENV.X} — load_env / expand_in_action so the same actions can target dev / staging / prod.
Data-driven runner — load_dataset_csv / load_dataset_json / run_with_dataset with ${ROW.col} placeholder expansion.

Test data & determinism

snapshot.fixture_record.FixtureRecorder("fx.json", mode="auto") — record once, replay forever; modes record / replay / auto.
database.fixtures.load_fixture_file("seed.json") + load_into_connection(conn, fixture) — seed Postgres / MySQL / SQLite from {table: [rows]} JSON.

OAuth2 / OIDC — client_credentials_token / password_grant_token / refresh_token_grant with in-process token cache that refreshes 30 s before expiry.
HTTP API — http_get / http_post / http_put / http_patch / http_delete plus http_assert_status and http_assert_json_contains.
Database — db_query / db_assert_count / db_assert_value / db_assert_exists / db_assert_empty; SQLAlchemy soft dependency, bound parameters only.

api_mock.MockRouter().add(method, url_pattern, body=, status=, times=) — supports literal, glob, and re: regex URL patterns; attach to a Playwright page with attach_to_page(page).
contract_testing.validate_response(body, schema) — JSON-Schema subset (type / properties / required / items / enum / oneOf / additionalProperties); validate_against_openapi resolves $ref and looks up paths[…].responses[…].
graphql.GraphQLClient(endpoint).execute(query, variables=) + extract_field(payload, "users[0].name").
mock_services — MockOAuthServer, MockSmtpServer, MockS3Storage for offline CI runs.