Remove build_from_settings().

scrapy/middleware.py

@@ -2,12 +2,13 @@ from __future__ import annotations
 
 import logging
 import pprint
+import warnings
 from collections import defaultdict, deque
 from typing import TYPE_CHECKING, Any, TypeVar, cast
 
-from scrapy.exceptions import NotConfigured
+from scrapy.exceptions import NotConfigured, ScrapyDeprecationWarning
 from scrapy.utils.defer import process_chain, process_parallel
-from scrapy.utils.misc import build_from_crawler, build_from_settings, load_object
+from scrapy.utils.misc import build_from_crawler, load_object
 
 if TYPE_CHECKING:
     from collections.abc import Callable, Iterable
@@ -20,7 +21,7 @@ if TYPE_CHECKING:
 
     from scrapy import Spider
     from scrapy.crawler import Crawler
-    from scrapy.settings import Settings
+    from scrapy.settings import BaseSettings, Settings
 
     _P = ParamSpec("_P")
 
@@ -50,8 +51,27 @@ class MiddlewareManager:
     def _get_mwlist_from_settings(cls, settings: Settings) -> list[Any]:
         raise NotImplementedError
 
+    @staticmethod
+    def _build_from_settings(objcls: type[_T], settings: BaseSettings) -> _T:
+        if hasattr(objcls, "from_settings"):
+            instance = objcls.from_settings(settings)  # type: ignore[attr-defined]
+            method_name = "from_settings"
+        else:
+            instance = objcls()
+            method_name = "__new__"
+        if instance is None:
+            raise TypeError(f"{objcls.__qualname__}.{method_name} returned None")
+        return cast(_T, instance)
+
     @classmethod
     def from_settings(cls, settings: Settings, crawler: Crawler | None = None) -> Self:
+        if crawler is None:
+            warnings.warn(
+                "Calling MiddlewareManager.from_settings() without a Crawler instance is deprecated."
+                " As this method will be deprecated in the future, please switch to from_crawler().",
+                category=ScrapyDeprecationWarning,
+                stacklevel=2,
+            )
         mwlist = cls._get_mwlist_from_settings(settings)
         middlewares = []
         enabled = []
@@ -61,7 +81,7 @@ class MiddlewareManager:
                 if crawler is not None:
                     mw = build_from_crawler(mwcls, crawler)
                 else:
-                    mw = build_from_settings(mwcls, settings)
+                    mw = MiddlewareManager._build_from_settings(mwcls, settings)
                 middlewares.append(mw)
                 enabled.append(clspath)
             except NotConfigured as e:

scrapy/utils/misc.py

@@ -26,7 +26,6 @@ if TYPE_CHECKING:
 
     from scrapy import Spider
     from scrapy.crawler import Crawler
-    from scrapy.settings import BaseSettings
 
 
 _ITERABLE_SINGLE_VALUES = dict, Item, str, bytes
@@ -150,7 +149,7 @@ def create_instance(objcls, settings, crawler, *args, **kwargs):
     """
     warnings.warn(
         "The create_instance() function is deprecated. "
-        "Please use build_from_crawler() or build_from_settings() instead.",
+        "Please use build_from_crawler() instead.",
         category=ScrapyDeprecationWarning,
         stacklevel=2,
     )
@@ -176,7 +175,7 @@ def create_instance(objcls, settings, crawler, *args, **kwargs):
 def build_from_crawler(
     objcls: type[T], crawler: Crawler, /, *args: Any, **kwargs: Any
 ) -> T:
-    """Construct a class instance using its ``from_crawler`` constructor.
+    """Construct a class instance using its ``from_crawler`` or ``from_settings`` constructor.
 
     ``*args`` and ``**kwargs`` are forwarded to the constructor.
 
@@ -196,26 +195,6 @@ def build_from_crawler(
     return cast(T, instance)
 
 
-def build_from_settings(
-    objcls: type[T], settings: BaseSettings, /, *args: Any, **kwargs: Any
-) -> T:
-    """Construct a class instance using its ``from_settings`` constructor.
-
-    ``*args`` and ``**kwargs`` are forwarded to the constructor.
-
-    Raises ``TypeError`` if the resulting instance is ``None``.
-    """
-    if hasattr(objcls, "from_settings"):
-        instance = objcls.from_settings(settings, *args, **kwargs)  # type: ignore[attr-defined]
-        method_name = "from_settings"
-    else:
-        instance = objcls(*args, **kwargs)
-        method_name = "__new__"
-    if instance is None:
-        raise TypeError(f"{objcls.__qualname__}.{method_name} returned None")
-    return cast(T, instance)
-
-
 @contextmanager
 def set_environ(**kwargs: str) -> Iterator[None]:
     """Temporarily set environment variables inside the context manager and

tests/test_middleware.py

@@ -2,7 +2,7 @@ from twisted.trial import unittest
 
 from scrapy.exceptions import NotConfigured
 from scrapy.middleware import MiddlewareManager
-from scrapy.settings import Settings
+from scrapy.utils.test import get_crawler
 
 
 class M1:
@@ -23,8 +23,6 @@ class M2:
     def close_spider(self, spider):
         pass
 
-    pass
-
 
 class M3:
     def process(self, response, request, spider):
@@ -83,7 +81,7 @@ class MiddlewareManagerTest(unittest.TestCase):
         self.assertEqual(mwman.middlewares, (m1, m2, m3))
 
     def test_enabled_from_settings(self):
-        settings = Settings()
-        mwman = TestMiddlewareManager.from_settings(settings)
+        crawler = get_crawler()
+        mwman = TestMiddlewareManager.from_crawler(crawler)
         classes = [x.__class__ for x in mwman.middlewares]
         self.assertEqual(classes, [M1, M3])

tests/test_utils_misc/__init__.py

@@ -10,7 +10,6 @@ from scrapy.item import Field, Item
 from scrapy.utils.misc import (
     arg_to_iter,
     build_from_crawler,
-    build_from_settings,
     create_instance,
     load_object,
     rel_has_nofollow,
@@ -197,39 +196,6 @@ class UtilsMiscTestCase(unittest.TestCase):
         with self.assertRaises(TypeError):
             build_from_crawler(m, crawler, *args, **kwargs)
 
-    def test_build_from_settings(self):
-        settings = mock.MagicMock()
-        args = (True, 100.0)
-        kwargs = {"key": "val"}
-
-        def _test_with_settings(mock, settings):
-            build_from_settings(mock, settings, *args, **kwargs)
-            if hasattr(mock, "from_settings"):
-                mock.from_settings.assert_called_once_with(settings, *args, **kwargs)
-                self.assertEqual(mock.call_count, 0)
-            else:
-                mock.assert_called_once_with(*args, **kwargs)
-
-        # Check usage of correct constructor using three mocks:
-        #   1. with no alternative constructors
-        #   2. with from_settings() constructor
-        #   3. with from_settings() and from_crawler() constructor
-        spec_sets = (
-            ["__qualname__"],
-            ["__qualname__", "from_settings"],
-            ["__qualname__", "from_settings", "from_crawler"],
-        )
-        for specs in spec_sets:
-            m = mock.MagicMock(spec_set=specs)
-            _test_with_settings(m, settings)
-            m.reset_mock()
-
-        # Check adoption of crawler settings
-        m = mock.MagicMock(spec_set=["__qualname__", "from_settings"])
-        m.from_settings.return_value = None
-        with self.assertRaises(TypeError):
-            build_from_settings(m, settings, *args, **kwargs)
-
     def test_set_environ(self):
         assert os.environ.get("some_test_environ") is None
         with set_environ(some_test_environ="test_value"):

tests/test_webclient.py

@@ -9,25 +9,18 @@ from tempfile import mkdtemp
 
 import OpenSSL.SSL
 from twisted.internet import defer, reactor
+from twisted.internet.defer import inlineCallbacks
+from twisted.internet.testing import StringTransport
+from twisted.protocols.policies import WrappingFactory
 from twisted.trial import unittest
 from twisted.web import resource, server, static, util
 
-try:
-    from twisted.internet.testing import StringTransport
-except ImportError:
-    # deprecated in Twisted 19.7.0
-    # (remove once we bump our requirement past that version)
-    from twisted.test.proto_helpers import StringTransport
-
-from twisted.internet.defer import inlineCallbacks
-from twisted.protocols.policies import WrappingFactory
-
 from scrapy.core.downloader import webclient as client
 from scrapy.core.downloader.contextfactory import ScrapyClientContextFactory
 from scrapy.http import Headers, Request
-from scrapy.settings import Settings
-from scrapy.utils.misc import build_from_settings
+from scrapy.utils.misc import build_from_crawler
 from scrapy.utils.python import to_bytes, to_unicode
+from scrapy.utils.test import get_crawler
 from tests.mockserver import (
     BrokenDownloadResource,
     ErrorResource,
@@ -469,22 +462,22 @@ class WebClientCustomCiphersSSLTestCase(WebClientSSLTestCase):
 
     def testPayload(self):
         s = "0123456789" * 10
-        settings = Settings({"DOWNLOADER_CLIENT_TLS_CIPHERS": self.custom_ciphers})
-        client_context_factory = build_from_settings(
-            ScrapyClientContextFactory, settings
+        crawler = get_crawler(
+            settings_dict={"DOWNLOADER_CLIENT_TLS_CIPHERS": self.custom_ciphers}
         )
+        client_context_factory = build_from_crawler(ScrapyClientContextFactory, crawler)
         return getPage(
             self.getURL("payload"), body=s, contextFactory=client_context_factory
         ).addCallback(self.assertEqual, to_bytes(s))
 
     def testPayloadDisabledCipher(self):
         s = "0123456789" * 10
-        settings = Settings(
-            {"DOWNLOADER_CLIENT_TLS_CIPHERS": "ECDHE-RSA-AES256-GCM-SHA384"}
-        )
-        client_context_factory = build_from_settings(
-            ScrapyClientContextFactory, settings
+        crawler = get_crawler(
+            settings_dict={
+                "DOWNLOADER_CLIENT_TLS_CIPHERS": "ECDHE-RSA-AES256-GCM-SHA384"
+            }
         )
+        client_context_factory = build_from_crawler(ScrapyClientContextFactory, crawler)
         d = getPage(
             self.getURL("payload"), body=s, contextFactory=client_context_factory
         )