undercooked/tests/e2e/conftest.py

"""Playwright fixtures for the browser suites in `tests/e2e/`.

The project depends on the `playwright` package, not on `pytest-playwright`, so
the three fixtures the plugin would provide are defined here — a headless chromium,
a fresh context and a fresh page, all function-scoped (see `browser` for why the scope
is load-bearing). A fresh context per test matters too: `sessionStorage` (the anonymous
`uc.token`, `uc.lastCode`) is scoped to it, so tests cannot observe each other's
identity.
"""

from __future__ import annotations

from typing import TYPE_CHECKING

import pytest
from playwright.sync_api import sync_playwright

if TYPE_CHECKING:
    from collections.abc import Iterator

    from playwright.sync_api import Browser, BrowserContext, Page, ViewportSize

# The default desktop viewport; story tests that care about small screens call
# `page.set_viewport_size` before navigating.
VIEWPORT: ViewportSize = {"width": 1280, "height": 720}


@pytest.fixture
def browser() -> Iterator[Browser]:
    """A headless chromium, live for exactly one test.

    Function scope is load-bearing, not shyness about startup time. The
    *synchronous* Playwright API drives the browser from an asyncio event loop it
    owns in the main thread, and that loop stays flagged as running for as long as
    `sync_playwright()` is open — so a session- or module-scoped fixture makes every
    later `async def` test in the run die with
    `RuntimeError: Runner.run() cannot be called from a running event loop`
    (pytest-asyncio, `asyncio_mode = "auto"`). Closing the whole stack inside the
    test leaves the main thread clean for whatever runs next.
    """
    with sync_playwright() as playwright:
        launched = playwright.chromium.launch(headless=True)
        try:
            yield launched
        finally:
            launched.close()


@pytest.fixture
def context(browser: Browser) -> Iterator[BrowserContext]:
    """A brand-new browser context per test: isolated storage and cookies."""
    created = browser.new_context(viewport=VIEWPORT)
    try:
        yield created
    finally:
        created.close()


@pytest.fixture
def page(context: BrowserContext) -> Iterator[Page]:
    """A tab inside `context`, closed after the test."""
    opened = context.new_page()
    try:
        yield opened
    finally:
        opened.close()