conftest.py

# Copyright (C) DATADVANCE, 2010-2023
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"""Auxiliary fixtures to simplify testing."""

import asyncio
import inspect
import sys
import threading

import channels
import django
import graphene
import pytest

import channels_graphql_ws
import channels_graphql_ws.testing


@pytest.fixture
def event_loop(request):
    """Overwrite `pytest_asyncio` eventloop to fix Windows issue.

    Default implementation causes `NotImplementedError` on Windows with
    Python 3.8, because they changed default eventloop in 3.8.

    NOTE: We do the same thing in the `example/settings.py` because it
    imports (and fails) before we have a chance to invoke this fixture.
    So, we could avoid adding this fixture, but I feel it is better to
    keep the proper solution here as well.

    """
    del request
    if sys.platform == "win32" and sys.version_info.minor >= 8:
        asyncio.set_event_loop_policy(
            asyncio.WindowsSelectorEventLoopPolicy()  # pylint: disable=no-member
        )
    loop = asyncio.get_event_loop_policy().new_event_loop()
    yield loop
    loop.close()


class DummyQuery(graphene.ObjectType):
    """Dummy query to use if no query supplied to the `gql` call.

    Graphene will throw a exception from the `graphene.Schema` constructor
    call if the `query` parameter is `None`. The `query` with no fields
    will also result in an exception.

    Our `gql` function should allow `None` value for the `query`
    parameter to make tests code simplier. So this "DummyQuery" will be
    used as a substitution for the `query` parameter of the
    `graphene.Schema` constructor call.
    """

    value = graphene.String()

    def resolve_value(self):
        """Resolver to return predefined value which can be tested."""
        del self
        return "test"


@pytest.fixture
def gql(db, request):
    """PyTest fixture for testing GraphQL WebSocket backends.

    The fixture provides a method to setup GraphQL testing backend for
    the given GraphQL schema (query, mutation, and subscription). In
    particular: it sets up an instance of `GraphqlWsConsumer` and an
    instance of `GraphqlWsClient`. The former one is returned
    from the function.

    Syntax:
        gql(
            *,
            query=None,
            mutation=None,
            subscription=None,
            consumer_attrs=None,
            communicator_kwds=None,
            subprotocol="graphql-transport-ws",
        ):

    Args:
        query: Root GraphQL query. Optional.
        mutation: Root GraphQL subscription. Optional.
        subscription: Root GraphQL mutation. Optional.
        consumer_attrs: `GraphqlWsConsumer` attributes dict. Optional.
        communicator_kwds: Extra keyword arguments for the Channels
            `channels.testing.WebsocketCommunicator`. Optional.
        subprotocol: WebSocket subprotocol to use by the Client. Can
            have a value of "graphql-transport-ws" or "graphql-ws".
            By default set to "graphql-transport-ws".

    Returns:
        An instance of the `GraphqlWsClient` class which has many
        useful GraphQL-related methods, see the `GraphqlWsClient`
        class docstrings for details.

    Use like this:
    ```
    def test_something(gql):
        client = gql(
            # GraphQl schema.
            query=MyQuery,
            mutation=MyMutation,
            subscription=MySubscription,
            # `GraphqlWsConsumer` settings.
            consumer_attrs={"strict_ordering": True},
            # `channels.testing.WebsocketCommunicator` settings.
            communicator_kwds={"headers": [...]},
            # Subprotocol to test.
            subprotocol="graphql-ws"
        )
        ...
    ```

    """
    # NOTE: We need Django DB to be initialized each time we work with
    # `GraphqlWsConsumer`, because it uses threads and sometimes calls
    # `django.db.close_old_connections()`.
    del db

    issued_clients = []

    def client_constructor(
        *,
        query=None,
        mutation=None,
        subscription=None,
        consumer_attrs=None,
        communicator_kwds=None,
        subprotocol="graphql-transport-ws",
    ):
        """Setup GraphQL consumer and the communicator for tests."""
        # Graphene will throw a exception from the `graphene.Schema`
        # constructor call if the `query` parameter is `None`. The
        # `query` with no fields will also result in exception.
        #
        # If no `query` provided to the `client_constructor`, then use
        # DummyQuery, since Graphene requires one.
        if query is None:
            query = DummyQuery

        class ChannelsConsumer(channels_graphql_ws.GraphqlWsConsumer):
            """Channels WebSocket consumer for GraphQL API."""

            # Redefine the group prefix to be able to detect that it is
            # really changed.
            group_name_prefix = "TEST"

            schema = graphene.Schema(
                query=query,
                mutation=mutation,
                subscription=subscription,
                auto_camelcase=False,
            )

        # Set additional attributes to the `ChannelsConsumer`.
        if consumer_attrs is not None:
            for attr, val in consumer_attrs.items():
                setattr(ChannelsConsumer, attr, val)

        application = channels.routing.ProtocolTypeRouter(
            {
                "websocket": channels.routing.URLRouter(
                    [django.urls.path("graphql/", ChannelsConsumer.as_asgi())]
                )
            }
        )

        transport = channels_graphql_ws.testing.GraphqlWsTransport(
            application=application,
            path="graphql/",
            communicator_kwds=communicator_kwds,
            subprotocol=subprotocol,
        )

        client = channels_graphql_ws.testing.GraphqlWsClient(
            transport, subprotocol=subprotocol
        )
        issued_clients.append(client)
        return client

    yield client_constructor

    # Assert all issued client are properly finalized.
    for client in reversed(issued_clients):
        assert (
            not client.connected
        ), f"Test has left connected client: {request.node.nodeid}!"


@pytest.fixture(scope="session", autouse=True)
def synchronize_inmemory_channel_layer():
    """Monkeypatch `InMemoryChannelLayer` to make it thread safe.

    The `InMemoryChannelLayer` is not thread safe by default since it use the
    `asyncio.Queue`.

    Without this we have a blinking fails in the unit tests run:
    Traceback (most recent call last):
        File ".../site-packages/promise/promise.py", line 842, in handle_future_result
            resolve(future.result())
        File ".../tests/test_concurrent.py", line 994, in mutate
            await OnChatMessageSentAsync.notify(message=message, user_id=user_id)
        File ".../tests/test_concurrent.py", line 940, in notify
            await super().broadcast(group=group, payload=message)
        File ".../channels_graphql_ws/graphql_ws.py", line 248, in broadcast_async
            "payload": serialized_payload,
        File ".../site-packages/channels/layers.py", line 351, in group_send
            for channel in self.groups.get(group, set()):
     graphql.error.GraphQLError:
         dictionary changed size during iteration
    """
    guard = threading.RLock()

    def wrap(func):
        if inspect.iscoroutinefunction(func):

            async def wrapper(*args, **kwds):
                with guard:
                    return await func(*args, **kwds)

        else:

            def wrapper(*args, **kwds):
                with guard:
                    return func(*args, **kwds)

        return wrapper

    # Carefully selected methods to protect. We cannot simply wrap all
    # the callables, cause this will lead to deadlocks, e.g. when we
    # locked the mutex in `await receive` and then another coroutine
    # calls `await send`.
    callables_to_protect = [
        "_clean_expired",
        "_remove_from_groups",
        "close",
        "flush",
        "group_add",
        "group_discard",
        "group_send",
        "new_channel",
        "send",
    ]
    for attr_name in callables_to_protect:
        setattr(
            channels.layers.InMemoryChannelLayer,
            attr_name,
            wrap(getattr(channels.layers.InMemoryChannelLayer, attr_name)),
        )


@pytest.fixture(scope="function", autouse=True)
def extra_print_in_the_beginning():
    """Improve output of `pytest -s` by adding EOL in the beginning."""
    print()