Use mypy 1.0 (#15052)

* Update mypy and mypy-zope
* Remove unused ignores

These used to suppress

```
synapse/storage/engines/__init__.py:28: error: "__new__" must return a
class instance (got "NoReturn")  [misc]
```

and

```
synapse/http/matrixfederationclient.py:1270: error: "BaseException" has no attribute "reasons"  [attr-defined]
```

(note that we check `hasattr(e, "reasons")` above)

* Avoid empty body warnings, sometimes by marking methods as abstract

E.g.

```
tests/handlers/test_register.py:58: error: Missing return statement  [empty-body]
tests/handlers/test_register.py:108: error: Missing return statement  [empty-body]
```

* Suppress false positive about `JaegerConfig`

Complaint was

```
synapse/logging/opentracing.py:450: error: Function "Type[Config]" could always be true in boolean context  [truthy-function]
```

* Fix not calling `is_state()`

Oops!

```
tests/rest/client/test_third_party_rules.py:428: error: Function "Callable[[], bool]" could always be true in boolean context  [truthy-function]
```

* Suppress false positives from ParamSpecs

````
synapse/logging/opentracing.py:971: error: Argument 2 to "_custom_sync_async_decorator" has incompatible type "Callable[[Arg(Callable[P, R], 'func'), **P], _GeneratorContextManager[None]]"; expected "Callable[[Callable[P, R], **P], _GeneratorContextManager[None]]"  [arg-type]
synapse/logging/opentracing.py:1017: error: Argument 2 to "_custom_sync_async_decorator" has incompatible type "Callable[[Arg(Callable[P, R], 'func'), **P], _GeneratorContextManager[None]]"; expected "Callable[[Callable[P, R], **P], _GeneratorContextManager[None]]"  [arg-type]
````

* Drive-by improvement to `wrapping_logic` annotation

* Workaround false "unreachable" positives

See https://github.com/Shoobx/mypy-zope/issues/91

```
tests/http/test_proxyagent.py:626: error: Statement is unreachable  [unreachable]
tests/http/test_proxyagent.py:762: error: Statement is unreachable  [unreachable]
tests/http/test_proxyagent.py:826: error: Statement is unreachable  [unreachable]
tests/http/test_proxyagent.py:838: error: Statement is unreachable  [unreachable]
tests/http/test_proxyagent.py:845: error: Statement is unreachable  [unreachable]
tests/http/federation/test_matrix_federation_agent.py:151: error: Statement is unreachable  [unreachable]
tests/http/federation/test_matrix_federation_agent.py:452: error: Statement is unreachable  [unreachable]
tests/logging/test_remote_handler.py:60: error: Statement is unreachable  [unreachable]
tests/logging/test_remote_handler.py:93: error: Statement is unreachable  [unreachable]
tests/logging/test_remote_handler.py:127: error: Statement is unreachable  [unreachable]
tests/logging/test_remote_handler.py:152: error: Statement is unreachable  [unreachable]
```

* Changelog

* Tweak DBAPI2 Protocol to be accepted by mypy 1.0

Some extra context in:
- https://github.com/matrix-org/python-canonicaljson/pull/57
- https://github.com/python/mypy/issues/6002
- https://mypy.readthedocs.io/en/latest/common_issues.html#covariant-subtyping-of-mutable-protocol-members-is-rejected

* Pull in updated canonicaljson lib

so the protocol check just works

* Improve comments in opentracing

I tried to workaround the ignores but found it too much trouble.

I think the corresponding issue is
https://github.com/python/mypy/issues/12909. The mypy repo has a PR
claiming to fix this (https://github.com/python/mypy/pull/14677) which
might mean this gets resolved soon?

* Better annotation for INTERACTIVE_AUTH_CHECKERS

* Drive-by AUTH_TYPE annotation, to remove an ignore

7 files changed, 65 insertions, 38 deletions

diff --git a/tests/handlers/test_register.py b/tests/handlers/test_register.py
index 782ef09cf4..1db99b3c00 100644
--- a/tests/handlers/test_register.py
+++ b/tests/handlers/test_register.py
@@ -62,7 +62,7 @@ class TestSpamChecker:
         request_info: Collection[Tuple[str, str]],
         auth_provider_id: Optional[str],
     ) -> RegistrationBehaviour:
-        pass
+        return RegistrationBehaviour.ALLOW
 
 
 class DenyAll(TestSpamChecker):
@@ -111,7 +111,7 @@ class TestLegacyRegistrationSpamChecker:
         username: Optional[str],
         request_info: Collection[Tuple[str, str]],
     ) -> RegistrationBehaviour:
-        pass
+        return RegistrationBehaviour.ALLOW
 
 
 class LegacyAllowAll(TestLegacyRegistrationSpamChecker):
diff --git a/tests/http/federation/test_matrix_federation_agent.py b/tests/http/federation/test_matrix_federation_agent.py
index acfdcd3bca..d27422515c 100644
--- a/tests/http/federation/test_matrix_federation_agent.py
+++ b/tests/http/federation/test_matrix_federation_agent.py
@@ -63,7 +63,7 @@ from tests.http import (
     get_test_ca_cert_file,
 )
 from tests.server import FakeTransport, ThreadedMemoryReactorClock
-from tests.utils import default_config
+from tests.utils import checked_cast, default_config
 
 logger = logging.getLogger(__name__)
 
@@ -146,8 +146,10 @@ class MatrixFederationAgentTests(unittest.TestCase):
         #
         # Normally this would be done by the TCP socket code in Twisted, but we are
         # stubbing that out here.
-        client_protocol = client_factory.buildProtocol(dummy_address)
-        assert isinstance(client_protocol, _WrappingProtocol)
+        # NB: we use a checked_cast here to workaround https://github.com/Shoobx/mypy-zope/issues/91)
+        client_protocol = checked_cast(
+            _WrappingProtocol, client_factory.buildProtocol(dummy_address)
+        )
         client_protocol.makeConnection(
             FakeTransport(server_protocol, self.reactor, client_protocol)
         )
@@ -446,7 +448,6 @@ class MatrixFederationAgentTests(unittest.TestCase):
         server_ssl_protocol = _wrap_server_factory_for_tls(
             _get_test_protocol_factory()
         ).buildProtocol(dummy_address)
-        assert isinstance(server_ssl_protocol, TLSMemoryBIOProtocol)
 
         # Tell the HTTP server to send outgoing traffic back via the proxy's transport.
         proxy_server_transport = proxy_server.transport
@@ -1529,7 +1530,7 @@ def _check_logcontext(context: LoggingContextOrSentinel) -> None:
 
 def _wrap_server_factory_for_tls(
     factory: IProtocolFactory, sanlist: Optional[List[bytes]] = None
-) -> IProtocolFactory:
+) -> TLSMemoryBIOFactory:
     """Wrap an existing Protocol Factory with a test TLSMemoryBIOFactory
     The resultant factory will create a TLS server which presents a certificate
     signed by our test CA, valid for the domains in `sanlist`
diff --git a/tests/http/test_proxyagent.py b/tests/http/test_proxyagent.py
index a817940730..22fdc7f5f2 100644
--- a/tests/http/test_proxyagent.py
+++ b/tests/http/test_proxyagent.py
@@ -43,6 +43,7 @@ from tests.http import (
 )
 from tests.server import FakeTransport, ThreadedMemoryReactorClock
 from tests.unittest import TestCase
+from tests.utils import checked_cast
 
 logger = logging.getLogger(__name__)
 
@@ -620,7 +621,6 @@ class MatrixFederationAgentTests(TestCase):
         server_ssl_protocol = _wrap_server_factory_for_tls(
             _get_test_protocol_factory()
         ).buildProtocol(dummy_address)
-        assert isinstance(server_ssl_protocol, TLSMemoryBIOProtocol)
 
         # Tell the HTTP server to send outgoing traffic back via the proxy's transport.
         proxy_server_transport = proxy_server.transport
@@ -757,12 +757,14 @@ class MatrixFederationAgentTests(TestCase):
         assert isinstance(proxy_server, HTTPChannel)
 
         # fish the transports back out so that we can do the old switcheroo
-        s2c_transport = proxy_server.transport
-        assert isinstance(s2c_transport, FakeTransport)
-        client_protocol = s2c_transport.other
-        assert isinstance(client_protocol, _WrappingProtocol)
-        c2s_transport = client_protocol.transport
-        assert isinstance(c2s_transport, FakeTransport)
+        # To help mypy out with the various Protocols and wrappers and mocks, we do
+        # some explicit casting. Without the casts, we hit the bug I reported at
+        # https://github.com/Shoobx/mypy-zope/issues/91 .
+        # We also double-checked these casts at runtime (test-time) because I found it
+        # quite confusing to deduce these types in the first place!
+        s2c_transport = checked_cast(FakeTransport, proxy_server.transport)
+        client_protocol = checked_cast(_WrappingProtocol, s2c_transport.other)
+        c2s_transport = checked_cast(FakeTransport, client_protocol.transport)
 
         # the FakeTransport is async, so we need to pump the reactor
         self.reactor.advance(0)
@@ -822,9 +824,9 @@ class MatrixFederationAgentTests(TestCase):
     @patch.dict(os.environ, {"http_proxy": "proxy.com:8888"})
     def test_proxy_with_no_scheme(self) -> None:
         http_proxy_agent = ProxyAgent(self.reactor, use_proxy=True)
-        assert isinstance(http_proxy_agent.http_proxy_endpoint, HostnameEndpoint)
-        self.assertEqual(http_proxy_agent.http_proxy_endpoint._hostStr, "proxy.com")
-        self.assertEqual(http_proxy_agent.http_proxy_endpoint._port, 8888)
+        proxy_ep = checked_cast(HostnameEndpoint, http_proxy_agent.http_proxy_endpoint)
+        self.assertEqual(proxy_ep._hostStr, "proxy.com")
+        self.assertEqual(proxy_ep._port, 8888)
 
     @patch.dict(os.environ, {"http_proxy": "socks://proxy.com:8888"})
     def test_proxy_with_unsupported_scheme(self) -> None:
@@ -834,25 +836,21 @@ class MatrixFederationAgentTests(TestCase):
     @patch.dict(os.environ, {"http_proxy": "http://proxy.com:8888"})
     def test_proxy_with_http_scheme(self) -> None:
         http_proxy_agent = ProxyAgent(self.reactor, use_proxy=True)
-        assert isinstance(http_proxy_agent.http_proxy_endpoint, HostnameEndpoint)
-        self.assertEqual(http_proxy_agent.http_proxy_endpoint._hostStr, "proxy.com")
-        self.assertEqual(http_proxy_agent.http_proxy_endpoint._port, 8888)
+        proxy_ep = checked_cast(HostnameEndpoint, http_proxy_agent.http_proxy_endpoint)
+        self.assertEqual(proxy_ep._hostStr, "proxy.com")
+        self.assertEqual(proxy_ep._port, 8888)
 
     @patch.dict(os.environ, {"http_proxy": "https://proxy.com:8888"})
     def test_proxy_with_https_scheme(self) -> None:
         https_proxy_agent = ProxyAgent(self.reactor, use_proxy=True)
-        assert isinstance(https_proxy_agent.http_proxy_endpoint, _WrapperEndpoint)
-        self.assertEqual(
-            https_proxy_agent.http_proxy_endpoint._wrappedEndpoint._hostStr, "proxy.com"
-        )
-        self.assertEqual(
-            https_proxy_agent.http_proxy_endpoint._wrappedEndpoint._port, 8888
-        )
+        proxy_ep = checked_cast(_WrapperEndpoint, https_proxy_agent.http_proxy_endpoint)
+        self.assertEqual(proxy_ep._wrappedEndpoint._hostStr, "proxy.com")
+        self.assertEqual(proxy_ep._wrappedEndpoint._port, 8888)
 
 
 def _wrap_server_factory_for_tls(
     factory: IProtocolFactory, sanlist: Optional[List[bytes]] = None
-) -> IProtocolFactory:
+) -> TLSMemoryBIOFactory:
     """Wrap an existing Protocol Factory with a test TLSMemoryBIOFactory
 
     The resultant factory will create a TLS server which presents a certificate
diff --git a/tests/logging/test_remote_handler.py b/tests/logging/test_remote_handler.py
index c08954d887..5191e31a8a 100644
--- a/tests/logging/test_remote_handler.py
+++ b/tests/logging/test_remote_handler.py
@@ -21,6 +21,7 @@ from synapse.logging import RemoteHandler
 from tests.logging import LoggerCleanupMixin
 from tests.server import FakeTransport, get_clock
 from tests.unittest import TestCase
+from tests.utils import checked_cast
 
 
 def connect_logging_client(
@@ -56,8 +57,8 @@ class RemoteHandlerTestCase(LoggerCleanupMixin, TestCase):
         client, server = connect_logging_client(self.reactor, 0)
 
         # Trigger data being sent
-        assert isinstance(client.transport, FakeTransport)
-        client.transport.flush()
+        client_transport = checked_cast(FakeTransport, client.transport)
+        client_transport.flush()
 
         # One log message, with a single trailing newline
         logs = server.data.decode("utf8").splitlines()
@@ -89,8 +90,8 @@ class RemoteHandlerTestCase(LoggerCleanupMixin, TestCase):
 
         # Allow the reconnection
         client, server = connect_logging_client(self.reactor, 0)
-        assert isinstance(client.transport, FakeTransport)
-        client.transport.flush()
+        client_transport = checked_cast(FakeTransport, client.transport)
+        client_transport.flush()
 
         # Only the 7 infos made it through, the debugs were elided
         logs = server.data.splitlines()
@@ -123,8 +124,8 @@ class RemoteHandlerTestCase(LoggerCleanupMixin, TestCase):
 
         # Allow the reconnection
         client, server = connect_logging_client(self.reactor, 0)
-        assert isinstance(client.transport, FakeTransport)
-        client.transport.flush()
+        client_transport = checked_cast(FakeTransport, client.transport)
+        client_transport.flush()
 
         # The 10 warnings made it through, the debugs and infos were elided
         logs = server.data.splitlines()
@@ -148,8 +149,8 @@ class RemoteHandlerTestCase(LoggerCleanupMixin, TestCase):
 
         # Allow the reconnection
         client, server = connect_logging_client(self.reactor, 0)
-        assert isinstance(client.transport, FakeTransport)
-        client.transport.flush()
+        client_transport = checked_cast(FakeTransport, client.transport)
+        client_transport.flush()
 
         # The first five and last five warnings made it through, the debugs and
         # infos were elided
diff --git a/tests/rest/client/test_auth.py b/tests/rest/client/test_auth.py
index 208ec44829..f4e1e7de43 100644
--- a/tests/rest/client/test_auth.py
+++ b/tests/rest/client/test_auth.py
@@ -43,6 +43,9 @@ class DummyRecaptchaChecker(UserInteractiveAuthChecker):
         super().__init__(hs)
         self.recaptcha_attempts: List[Tuple[dict, str]] = []
 
+    def is_enabled(self) -> bool:
+        return True
+
     def check_auth(self, authdict: dict, clientip: str) -> Any:
         self.recaptcha_attempts.append((authdict, clientip))
         return succeed(True)
diff --git a/tests/rest/client/test_third_party_rules.py b/tests/rest/client/test_third_party_rules.py
index 3325d43a2f..5fa3440691 100644
--- a/tests/rest/client/test_third_party_rules.py
+++ b/tests/rest/client/test_third_party_rules.py
@@ -425,7 +425,7 @@ class ThirdPartyRulesTestCase(unittest.FederatingHomeserverTestCase):
         async def test_fn(
             event: EventBase, state_events: StateMap[EventBase]
         ) -> Tuple[bool, Optional[JsonDict]]:
-            if event.is_state and event.type == EventTypes.PowerLevels:
+            if event.is_state() and event.type == EventTypes.PowerLevels:
                 await api.create_and_send_event_into_room(
                     {
                         "room_id": event.room_id,
diff --git a/tests/utils.py b/tests/utils.py
index 15fabbc2d0..a0ac11bc5c 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -15,7 +15,7 @@
 
 import atexit
 import os
-from typing import Any, Callable, Dict, List, Tuple, Union, overload
+from typing import Any, Callable, Dict, List, Tuple, Type, TypeVar, Union, overload
 
 import attr
 from typing_extensions import Literal, ParamSpec
@@ -341,3 +341,27 @@ async def create_room(hs: HomeServer, room_id: str, creator_id: str) -> None:
     context = await unpersisted_context.persist(event)
 
     await persistence_store.persist_event(event, context)
+
+
+T = TypeVar("T")
+
+
+def checked_cast(type: Type[T], x: object) -> T:
+    """A version of typing.cast that is checked at runtime.
+
+    We have our own function for this for two reasons:
+
+    1. typing.cast itself is deliberately a no-op at runtime, see
+       https://docs.python.org/3/library/typing.html#typing.cast
+    2. To help workaround a mypy-zope bug https://github.com/Shoobx/mypy-zope/issues/91
+       where mypy would erroneously consider `isinstance(x, type)` to be false in all
+       circumstances.
+
+    For this to make sense, `T` needs to be something that `isinstance` can check; see
+        https://docs.python.org/3/library/functions.html?highlight=isinstance#isinstance
+        https://docs.python.org/3/glossary.html#term-abstract-base-class
+        https://docs.python.org/3/library/typing.html#typing.runtime_checkable
+    for more details.
+    """
+    assert isinstance(x, type)
+    return x