Pytest recommendations

[srgee]

I'm looking for some recommendations or best practices for testing Reflex apps with pytest. Does anyone can point me to good examples or provide some guidelines? Do we need pytest-asyncio?

[FarhanAliRaza]

Testing Reflex apps with pytest

Two layers cover most needs:

1. Static component tests — call your page/section functions and walk
the returned rx.Component tree. No browser, sub-second. Catches typos
and missing sections.

2. End-to-end with reflex.testing.AppHarness + Playwright — boots
the real app and drives a headless browser.

# conftest.py — session-scoped so the dev server boots once
from pathlib import Path
import pytest
from reflex.testing import AppHarness

@pytest.fixture(scope="session")
def my_app():
    app_root = Path(__file__).parent.parent  # dir containing rxconfig.py
    with AppHarness.create(root=app_root) as harness:
        yield harness

# test_e2e.py
from playwright.sync_api import Page, expect

def test_homepage(my_app, page: Page):
    page.goto(my_app.frontend_url)
    expect(page.get_by_role("button", name="Sign Up")).to_be_visible()

Run: uv run playwright install (once), then uv run pytest tests/.

Reference examples in the Reflex repo

• A real Reflex app being tested by its maintainers —
  docs/app/tests/
  in reflex-dev/reflex. See conftest.py for the AppHarness.create(root=...)
  pattern and a pytest_runtest_makereport hook that keeps Playwright
  videos only for failed tests.
• Framework integration tests —
  tests/integration/tests_playwright/
  shows the factory-function variant (app_source=MyApp), useful for
  isolating a single behavior in a synthetic mini-app.

Do you need pytest-asyncio?

Only if you call async Reflex internals directly in a test —
state handlers, the state manager, the event processor. Examples in the
repo:

• tests/units/test_state.py test_process_event_simple — awaits an
  event processor and asserts on emitted deltas.
• tests/units/test_app.py test_set_and_get_state — awaits
  app.state_manager.get_state(...).

The framework's pyproject.toml sets asyncio_mode = "auto" so those
tests skip the @pytest.mark.asyncio marker.

For e2e tests through AppHarness + Playwright, you don't need it.
Playwright's sync API blocks on each call, AppHarness runs uvicorn in a
background thread. docs/app/tests/ doesn't import pytest-asyncio at all.