plain-testing changelog

0.1.0 (2026-10-06)

What's changed

• First release. plain.testing is Plain's own test runner and the test client, replacing plain.pytest. A test is a function in tests/**/test_*.py that makes a bare assert; a file is the group, and there are no test classes, fixtures or conftest.py. Client makes a request to the app in-process and returns the response that would have been sent, with form_data=, json_data=, query_params=, files= and the rest of the request vocabulary, and client.websocket() for WebSocket views. @cases, @skip and @tag attach static facts; override_settings, patch, raises, skip_test and the captures (capture_spans, capture_metrics, capture_logs) are used in the body. Installed packages protect every test through a TestLifecycle (plain.postgres rolls each test back, plain.email resets the outbox) and a project adds its own in tests/lifecycle.py (2278c086af)
• plain test runs them: a target is a directory, a file, a test (tests/test_x.py::test_name) or a line (tests/test_x.py:42); --match, --tag, --exclude-tag, --fail-fast, --verbose, --show-output, --full-values, --json and --list-passed, each with one name. A run that passes prints two lines. A failure prints every value inside the assert, a diff for large values, the test's locals, what the test wrote, and the command that runs it again; --json renders the same run as one document. Exit codes run 0 to 4, and 130 (2278c086af)
• A run reports where its time went, under --verbose or whenever more than a second is spent outside the tests: imports, each setup hook, the test database, the tests. The report is always in --json (2278c086af)
• Requires plain>=0.166.0, which has the in-process server the client is built on (2278c086af)

Upgrade instructions

• uv add plain.testing --dev, then plain agent install. Moving a suite from pytest is described step by step in the pull request that introduced the package: dependencies, rule files, commands and flags, what conftest.py guarded against, fixtures, classes, the client, and what the first run reports.