async def test_flat_map_monad():
m = rx.single(42)
def mapper(x: int) -> AsyncObservable[int]:
return rx.single(x * 10)
a = await rx.run(pipe(m, rx.flat_map(mapper)))
b = await rx.run(rx.single(420))
assert a == b
async def search_wikipedia(term: str) -> rx.AsyncObservable[str]:
"""Search Wikipedia for a given term"""
url = "http://en.wikipedia.org/w/api.php"
params = {"action": "opensearch", "search": term, "format": "json"}
async with aiohttp.ClientSession() as session:
async with session.get(url, params=params) as resp:
json_response = await resp.text()
return rx.single(json_response)
async def test_flat_map_monad_law_right_identity():
# m >>= return is no different than just m.
m = rx.single("move on up")
def mapper(x: str) -> AsyncObservable[str]:
return rx.single(x)
a = await rx.run(pipe(m, rx.flat_map(mapper)))
b = await rx.run(m)
assert a == b
async def test_flat_map_monad_law_left_identity():
# return x >>= f is the same thing as f x
x = 3
def f(x: int) -> AsyncObservable[int]:
return rx.single(x + 100000)
a = await rx.run(pipe(rx.single(x), rx.flat_map(f)))
b = await rx.run(f(x))
assert a == b
async def test_unit_observer_throws():
error = Exception("error")
xs = rx.single(42)
async def asend(value: int) -> None:
raise error
obv = AsyncTestObserver(asend)
await xs.subscribe_async(obv)
try:
await obv
except Exception as ex:
assert ex == error
assert obv.values == [(0, OnNext(42)), (0, OnError(error))]
async def test_unit_close():
xs = rx.single(42)
sub: Optional[AsyncDisposable] = None
async def asend(value: int) -> None:
assert sub is not None
await sub.dispose_async()
await asyncio.sleep(0)
obv: AsyncTestObserver[int] = AsyncTestObserver(asend)
sub = await xs.subscribe_async(obv)
await obv
assert obv.values == [
(0, OnNext(42)),
(0, OnCompleted),
]
async def test_flat_map_monad_law_associativity():
# (m >>= f) >>= g is just like doing m >>= (\x -> f x >>= g)
m = rx.single(42)
def f(x: int) -> AsyncObservable[int]:
return rx.single(x + 1000)
def g(y: int) -> AsyncObservable[int]:
return rx.single(y * 333)
def h(x: int) -> AsyncObservable[int]:
return pipe(f(x), rx.flat_map(g))
zs = pipe(m, rx.flat_map(f))
a = await rx.run(pipe(zs, rx.flat_map(g)))
b = await rx.run(pipe(m, rx.flat_map(h)))
assert a == b
def g(y: int) -> AsyncObservable[int]:
return rx.single(y * 333)
def f(x: int) -> AsyncObservable[int]:
return rx.single(x + 1000)
def mapper(x: str) -> AsyncObservable[str]:
return rx.single(x)
def mapper(x: int) -> AsyncObservable[int]:
return rx.single(x * 10)
async def test_unit_happy():
xs = rx.single(42)
obv: AsyncTestObserver[int] = AsyncTestObserver()
await rx.run(xs, obv)
assert obv.values == [(0, OnNext(42)), (0, OnCompleted)]
