From a85b3dfb2a2835bfe1f2c47a5719e2f8a001819d Mon Sep 17 00:00:00 2001
From: Florian Sesser <florian@leastauthority.com>
Date: Mon, 4 Nov 2024 15:42:56 +0000
Subject: [PATCH] attrs 24 dropped 'provides()' from its API

... and provided this copypasta for people who
rely on it, see https://github.com/python-attrs/attrs/pull/1265
---
 src/_zkapauthorizer/_attrs_zope.py     | 39 ++++++++++++++++++++++++++
 src/_zkapauthorizer/_storage_client.py |  2 +-
 src/_zkapauthorizer/_storage_server.py |  3 +-
 3 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100644 src/_zkapauthorizer/_attrs_zope.py

diff --git a/src/_zkapauthorizer/_attrs_zope.py b/src/_zkapauthorizer/_attrs_zope.py
new file mode 100644
index 00000000..efda9568
--- /dev/null
+++ b/src/_zkapauthorizer/_attrs_zope.py
@@ -0,0 +1,39 @@
+import attrs
+
+@attrs.define(repr=False)
+class _ProvidesValidator:
+    interface = attrs.field()
+
+    def __call__(self, inst, attr, value):
+        """
+        We use a callable class to be able to change the ``__repr__``.
+        """
+        if not self.interface.providedBy(value):
+            msg = f"'{attr.name}' must provide {self.interface!r} which {value!r} doesn't."
+            raise TypeError(
+                msg,
+                attr,
+                self.interface,
+                value,
+            )
+
+    def __repr__(self):
+        return f"<provides validator for interface {self.interface!r}>"
+
+
+def provides(interface):
+    """
+    A validator that raises a `TypeError` if the initializer is called
+    with an object that does not provide the requested *interface* (checks are
+    performed using ``interface.providedBy(value)`` (see `zope.interface
+    <https://zopeinterface.readthedocs.io/en/latest/>`_).
+
+    :param interface: The interface to check for.
+    :type interface: ``zope.interface.Interface``
+
+    :raises TypeError: With a human readable error message, the attribute
+        (of type `attrs.Attribute`), the expected interface, and the
+        value it got.
+    """
+    return _ProvidesValidator(interface)
+
diff --git a/src/_zkapauthorizer/_storage_client.py b/src/_zkapauthorizer/_storage_client.py
index 93085e4f..63ce9491 100644
--- a/src/_zkapauthorizer/_storage_client.py
+++ b/src/_zkapauthorizer/_storage_client.py
@@ -24,7 +24,6 @@
 from typing import Any, Awaitable, Callable, Optional, Protocol, TypeVar
 
 from allmydata.interfaces import IStorageServer
-from attr.validators import provides
 from attrs import Factory, define, field
 from foolscap.ipb import IRemoteReference
 from foolscap.referenceable import RemoteReference
@@ -51,6 +50,7 @@
     slot_testv_and_readv_and_writev_message,
 )
 from .validators import positive_integer
+from ._attrs_zope import provides
 
 _T = TypeVar("_T")
 _P = ParamSpec("_P")
diff --git a/src/_zkapauthorizer/_storage_server.py b/src/_zkapauthorizer/_storage_server.py
index 0609fc3a..7e74a439 100644
--- a/src/_zkapauthorizer/_storage_server.py
+++ b/src/_zkapauthorizer/_storage_server.py
@@ -59,7 +59,7 @@
 from allmydata.storage.server import StorageServer
 from allmydata.storage.shares import get_share_file
 from allmydata.util.base32 import b2a
-from attr.validators import instance_of, provides
+from attr.validators import instance_of
 from attrs import field, frozen
 from challenge_bypass_ristretto import (
     PublicKey,
@@ -94,6 +94,7 @@
     slot_testv_and_readv_and_writev_message,
 )
 from .validators import positive_integer
+from ._attrs_zope import provides
 
 # See allmydata/storage/mutable.py
 SLOT_HEADER_SIZE = 468