Ch3 Comments about book HOT 4 CLOSED

Is there supposed to be an @DataClass annotation on FakeSession? Otherwise there is a class instance and object instance "committed" variable. If not, deleting the "committed = False" line will be OK.

that was me. intention is to have the default .committed be False for all instances, but any instance that calls commit() will get its attribute set to True.

this may be a bit of Python weirdness?

>>> class Classy:
...     attribute = False
... 
>>> instance = Classy()
>>> instance.attribute
False
>>> instance.attribute = True
>>> instance.attribute
True
>>> Classy.attribute
False

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Re: the fake session, I see what you were going for (kind of a "Copy-on-Write"). It is a bit unusual, and looks maybe like it was a mistake The scenarios I am thinking are things like this:

class Thing(object):
    stack = [1, 2, 3]

    def pop(self):
        return self.stack.pop()

    def push(self, val):
        return self.stack.append(val)

def test_first():
    assert Thing().pop() == 3

def test_second():
    assert Thing().pop() == 3

def test_third():
    thing = Thing()
    thing.push(100)
    assert thing.stack == [1, 2, 3, 100]

If you run that with a test randomizer or a parallel-runner using threads, the tests looks will look like they fail randomly due to the shared state.

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I suppose people are going to cargo-cult copy these sorts of code listings so maybe we should be careful not to leave footguns like that lying around? will add a note to change it when i get a moment... thanks Ed.

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re: the first comment about making the random-reference-generators more readable, i found that quite appealing. here's what i've been playing around with so far:

def random_suffix():
    return uuid.uuid4().hex[:6]

def random_sku(name=''):
    return f'sku-{name}-{random_suffix()}'

def random_batchref(name=''):
    return f'batch-{name}-{random_suffix()}'

def random_orderid(name=''):
    return f'order-{name}-{random_suffix()}


@pytest.mark.usefixtures('postgres_db')
@pytest.mark.usefixtures('restart_api')
def test_happy_path_returns_201_and_allocated_batch():
    sku, othersku = random_sku('desirable-chair'), random_sku('ugly-chair')
    oldbatch, newbatch = random_batchref('old'), random_batchref('new')
    otherbatch = random_batchref('other')
    post_to_add_batch(oldbatch, sku, 100, '2011-01-02')
    post_to_add_batch(newbatch, sku, 100, '2011-01-01')
    post_to_add_batch(otherbatch, othersku, 100, None)

    data = {'orderid': random_orderid(), 'sku': sku, 'qty': 3}
    url = config.get_api_url()
    r = requests.post(f'{url}/allocate', json=data)
    assert r.status_code == 201

    assert r.json()['batchref'] == newbatch

worth it? overengineered? what do y'all think?

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