pytest-deck

An interactive browser dashboard for pytest. Collect your suite as a foldable tree, pick what to run with checkboxes or marker chips, and watch results stream in test by test, with tracebacks and captured output one click away.

Its defining promise: a deck run matches a real command-line pytest run. Every collect, reload, and run is a fresh python -m pytest subprocess, never in-process. What you see in the browser is what your terminal would say, and a crashing or hanging test can't take the dashboard down with it.

Beta. Collect, select, run with live streaming, reload with diff, plugin switches, coverage down to a source gutter, benchmark timings, and per-test attachments all work. See the changelog and the docs for the full picture.

Install

pip install pytest-deck

Quick start

pytest-deck is a pytest plugin. Launch the dashboard with --deck:

pytest --deck                 # dashboard for the current project (rootdir)
pytest --deck path/to/tests   # dashboard for a specific path

Nothing runs in the terminal. The deck prints its URL (http://127.0.0.1:8765/ by default); open it in your browser and your suite is there as a foldable tree.

Without --deck the plugin is inert: your normal pytest runs are completely unaffected.

To see everything at once, point the deck at this repo's examples/ suite. Install the plugins you want to try and run pytest --deck examples/.

For the full tour, start with the quickstart.

Features

The live basics

• A foldable file → class → test → parametrized-variant tree with rollup counts on every group.
• Select with checkboxes, marker chips that bulk-select every matching test, and -k / -m expression fields.
• Hit ▶ Run and PASS / FAIL / ERROR / SKIP stream in live as each test finishes, tracebacks in pytest's own colors, captured output alongside. The run summary's FAILED lines carry the same clickable badge, and every traceback has a copy button.
• Re-run failed: one click re-runs everything currently failed or errored, regardless of the selection.
• ↻ Collect to re-collect after an edit: added, removed, and changed tests are flagged, and selection plus results are preserved for tests that still exist.

Plugins

Installed plugins appear as switches in the sidebar, each with a typed config form, so you never have to hunt through a plugin's flags. Switches ship ready-made for:

• pytest-cov
• pytest-benchmark
• pytest-mpl
• pytest-metadata
• pytest-mock
• pytest-asyncio
• pytest-django

For any other plugin, a one-file TOML description (a manifest) in .pytest-deck/plugins/ adds a switch of your own.

Your ini addopts aren't lost either. Each token either prefills a switch's config form, follows its plugin's switch automatically, or shows up as a clickable suggestion chip. Nothing is dropped silently.

→ Plugins guide · Writing your own manifest

Standalone server

The dashboard also runs without the pytest CLI:

pytest-deck path/to/tests            # console script
python -m pytest_deck.server path/to/tests

One difference from pytest --deck path/to/tests: the standalone command roots the project at the path you give, with no walk up to find the root.

Options: --host (default 127.0.0.1), --port (must be free; default: first free port from 8765, up to 8785, announcing any fallback), and --open (open a browser tab on launch; off by default). Through pytest, --deck-port is the same as --port.

How it works

Every collect and run is a fresh pytest subprocess. A small plugin injected into those subprocesses emits structured JSON on a dedicated file descriptor, a private channel that keeps machine-readable results separate from pytest's captured output. A FastAPI backend streams those events to the browser over Server-Sent Events. The deep dive lives in the docs: How It Works.

Documentation

Full documentation is at pytest-deck.readthedocs.io:

• Getting started: install and first run.
• User guide: the dashboard, plugins, coverage, attachments, troubleshooting.
• Plugin integration: how manifests work and how to write one.
• How it works: architecture and design invariants.

Limitations

• pytest-xdist is not supported. The deck reads each run's results over a dedicated pipe, and xdist's worker subprocesses don't inherit that pipe, so results would never reach the dashboard. The deck therefore forces -p no:xdist for its own runs: if xdist is installed in your project it stays disabled here, and runs are serial.
• Localhost only. The server binds to 127.0.0.1 with no auth, and it executes your test code. Don't expose it on an untrusted network.

Development

Requires Python 3.11+ and Node 24 LTS (for the frontend build).

# backend
pip install -e ".[test]"
pytest                       # the full suite

# frontend (Svelte 5 + Vite); builds into pytest_deck/static/
cd frontend
npm install
npm run build

Run the full matrix (Python 3.11 to 3.14 × pytest 8/9, plus the frontend build) with tox. The development guide has the details.

pytest-deck is written with AI assistance. The design decisions, the reviews, and the bugs are mine. AI-assisted contributions are welcome here, held to the same bar.

License

MIT