pythonnative/tests/test_async_hooks.py at main · pythonnative/pythonnative · GitHub

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"""Unit tests for async effects (use_effect), pn.use_query, pn.use_mutation."""

from __future__ import annotations

import asyncio

from typing import Any

import pytest

from pythonnative.component import component

from pythonnative.element import Element

from pythonnative.hooks import (

MutationCall,

QueryResult,

use_effect,

use_mutation,

use_query,

use_state,

)

from pythonnative.reconciler import Reconciler

from pythonnative.runtime import drain, run_blocking

from pythonnative.testing import FakeBackend as _StubBackend

def _settle(rec: Reconciler, predicate: Any, timeout: float = 2.0) -> bool:

"""Pump the framework loop and flush renders until ``predicate`` holds."""

import time

deadline = time.monotonic() + timeout

while time.monotonic() < deadline:

drain(timeout=0.05)

rec.flush_dirty()

if predicate():

return True

return False

# ======================================================================

# Async use_effect (coroutine effects)

# ======================================================================

def test_async_effect_runs_on_mount() -> None:

fired: list = []

@component

def screen() -> Element:

async def effect() -> None:

fired.append(True)

use_effect(effect, [])

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen())

drain()

assert fired == [True]

def test_async_effect_cancels_on_unmount() -> None:

events: list = []

@component

def screen() -> Element:

async def effect() -> None:

events.append("started")

try:

await asyncio.sleep(5.0)

except asyncio.CancelledError:

events.append("cancelled")

raise

use_effect(effect, [])

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen())

drain(until=lambda: "started" in events)

assert events == ["started"]

rec.unmount()

drain(until=lambda: "cancelled" in events)

assert events == ["cancelled", "started"] or events == ["started", "cancelled"]

def test_async_effect_reruns_on_deps_change() -> None:

fired_with: list = []

@component

def screen(value: int = 0) -> Element:

async def effect() -> None:

fired_with.append(value)

use_effect(effect, [value])

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen(0))

drain()

assert fired_with == [0]

rec.reconcile(screen(1))

drain()

assert fired_with == [0, 1]

rec.reconcile(screen(1))

drain()

# Same value: no rerun.

assert fired_with == [0, 1]

def test_async_effect_completed_cleanup_runs() -> None:

"""An async effect that returns a callable gets that callable run

as its cleanup once the effect re-runs or the component unmounts."""

events: list = []

@component

def screen() -> Element:

async def effect() -> Any:

events.append("ran")

return lambda: events.append("cleaned")

use_effect(effect, [])

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen())

drain()

assert events == ["ran"]

rec.unmount()

drain()

assert events == ["ran", "cleaned"]

def test_sync_effect_still_works() -> None:

events: list = []

@component

def screen() -> Element:

def effect() -> Any:

events.append("ran")

return lambda: events.append("cleaned")

use_effect(effect, [])

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen())

assert events == ["ran"]

rec.unmount()

assert events == ["ran", "cleaned"]

def test_async_effect_state_update_triggers_local_rerender() -> None:

"""The core async-first loop: an async effect awaits, sets state,

and the component re-renders locally, all on one thread."""

snapshots: list = []

@component

def screen() -> Element:

message, set_message = use_state("loading")

snapshots.append(message)

async def load() -> None:

await asyncio.sleep(0)

set_message("done")

use_effect(load, [])

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen())

assert snapshots[-1] == "loading"

assert _settle(rec, lambda: snapshots[-1] == "done")

# ======================================================================

# use_query

# ======================================================================

def test_use_query_resolves_to_data() -> None:

captured: list = []

@component

def screen() -> Element:

async def fetcher() -> str:

return "hello"

q = use_query(fetcher, [])

captured.append(q)

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen())

# First snapshot is loading=True.

assert captured[0].loading is True

assert captured[0].data is None

assert _settle(rec, lambda: captured[-1].data == "hello")

assert captured[-1].loading is False

assert captured[-1].error is None

def test_use_query_captures_error() -> None:

captured: list = []

@component

def screen() -> Element:

async def fetcher() -> str:

raise RuntimeError("boom")

q = use_query(fetcher, [])

captured.append(q)

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen())

assert _settle(rec, lambda: captured[-1].error is not None)

assert isinstance(captured[-1].error, RuntimeError)

assert captured[-1].loading is False

def test_use_query_refetches_when_called() -> None:

counter = {"calls": 0}

captured: list = []

@component

def screen() -> Element:

async def fetcher() -> int:

counter["calls"] += 1

return counter["calls"]

q = use_query(fetcher, [])

captured.append(q)

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen())

assert _settle(rec, lambda: captured[-1].data == 1)

captured[-1].refetch()

assert _settle(rec, lambda: captured[-1].data == 2)

def test_use_query_with_a_key_refetches_with_the_latest_fetcher() -> None:

captured: list = []

@component

def screen(label: str) -> Element:

async def fetcher() -> str:

return label

captured.append(use_query(fetcher, key="fixed"))

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen("first"))

assert _settle(rec, lambda: captured[-1].data == "first")

rec.reconcile(screen("second"))

captured[-1].refetch()

assert _settle(rec, lambda: captured[-1].data == "second")

def test_use_query_returns_query_result_dataclass() -> None:

captured: list = []

@component

def screen() -> Element:

q = use_query(lambda: _resolved("x"), [])

captured.append(q)

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen())

assert isinstance(captured[0], QueryResult)

async def _resolved(value: Any) -> Any:

return value

# ======================================================================

# use_mutation

# ======================================================================

def test_use_mutation_runs_and_resolves() -> None:

captured_state: list = []

triggered: list = []

@component

def screen() -> Element:

async def mutator(x: int) -> int:

return x * 2

state, mutate = use_mutation(mutator)

captured_state.append(state)

triggered.append(mutate)

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen())

assert captured_state[0].loading is False

assert captured_state[0].data is None

call = triggered[-1](7)

assert isinstance(call, MutationCall)

assert _settle(rec, lambda: captured_state[-1].data == 14)

assert captured_state[-1].loading is False

def test_use_mutation_awaitable_returns_value() -> None:

triggered: list = []

@component

def screen() -> Element:

async def mutator(x: int) -> int:

return x + 1

_state, mutate = use_mutation(mutator)

triggered.append(mutate)

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen())

mutate = triggered[-1]

async def call_and_await() -> int:

return await mutate(41)

assert run_blocking(call_and_await(), timeout=2.0) == 42

def test_use_mutation_captures_error() -> None:

captured_state: list = []

triggered: list = []

@component

def screen() -> Element:

async def mutator() -> None:

raise ValueError("fail")

state, mutate = use_mutation(mutator)

captured_state.append(state)

triggered.append(mutate)

return Element("View", {}, [])

rec = Reconciler(_StubBackend())

rec.mount(screen())

call = triggered[-1]()

# Discarding the call is fine; the state will reflect the failure.

assert _settle(rec, lambda: captured_state[-1].error is not None)

assert isinstance(captured_state[-1].error, ValueError)

assert call.done() is True

# Suppress unused-import lint when running just the file.

_ = pytest

pythonnative/tests/test_async_hooks.py at main · pythonnative/pythonnative · GitHub

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