Add tests for TWISTED_REACTOR in custom_settings.

tests/CrawlerProcess/twisted_reactor_custom_settings.py

@@ -0,0 +1,14 @@
+import scrapy
+from scrapy.crawler import CrawlerProcess
+
+
+class AsyncioReactorSpider(scrapy.Spider):
+    name = 'asyncio_reactor'
+    custom_settings = {
+        "TWISTED_REACTOR": "twisted.internet.asyncioreactor.AsyncioSelectorReactor",
+    }
+
+
+process = CrawlerProcess()
+process.crawl(AsyncioReactorSpider)
+process.start()

tests/CrawlerProcess/twisted_reactor_custom_settings_conflict.py

@@ -0,0 +1,22 @@
+import scrapy
+from scrapy.crawler import CrawlerProcess
+
+
+class PollReactorSpider(scrapy.Spider):
+    name = 'poll_reactor'
+    custom_settings = {
+        "TWISTED_REACTOR": "twisted.internet.pollreactor.PollReactor",
+    }
+
+
+class AsyncioReactorSpider(scrapy.Spider):
+    name = 'asyncio_reactor'
+    custom_settings = {
+        "TWISTED_REACTOR": "twisted.internet.asyncioreactor.AsyncioSelectorReactor",
+    }
+
+
+process = CrawlerProcess()
+process.crawl(PollReactorSpider)
+process.crawl(AsyncioReactorSpider)
+process.start()

tests/CrawlerProcess/twisted_reactor_custom_settings_same.py

@@ -0,0 +1,21 @@
+import scrapy
+from scrapy.crawler import CrawlerProcess
+
+
+class AsyncioReactorSpider1(scrapy.Spider):
+    name = 'asyncio_reactor1'
+    custom_settings = {
+        "TWISTED_REACTOR": "twisted.internet.asyncioreactor.AsyncioSelectorReactor",
+    }
+
+class AsyncioReactorSpider2(scrapy.Spider):
+    name = 'asyncio_reactor2'
+    custom_settings = {
+        "TWISTED_REACTOR": "twisted.internet.asyncioreactor.AsyncioSelectorReactor",
+    }
+
+
+process = CrawlerProcess()
+process.crawl(AsyncioReactorSpider1)
+process.crawl(AsyncioReactorSpider2)
+process.start()

tests/test_crawler.py

@@ -361,6 +361,30 @@ class CrawlerProcessSubprocess(ScriptRunnerMixin, unittest.TestCase):
         self.assertIn("Spider closed (finished)", log)
         self.assertIn("Using reactor: twisted.internet.asyncioreactor.AsyncioSelectorReactor", log)
 
+    # https://twistedmatrix.com/trac/ticket/9766
+    @skipIf(platform.system() == 'Windows' and sys.version_info >= (3, 8),
+            "the asyncio reactor is broken on Windows when running Python ≥ 3.8")
+    def test_reactor_asyncio_custom_settings(self):
+        log = self.run_script("twisted_reactor_custom_settings.py")
+        self.assertIn("Spider closed (finished)", log)
+        self.assertIn("Using reactor: twisted.internet.asyncioreactor.AsyncioSelectorReactor", log)
+
+    # https://twistedmatrix.com/trac/ticket/9766
+    @skipIf(platform.system() == 'Windows' and sys.version_info >= (3, 8),
+            "the asyncio reactor is broken on Windows when running Python ≥ 3.8")
+    def test_reactor_asyncio_custom_settings_same(self):
+        log = self.run_script("twisted_reactor_custom_settings_same.py")
+        self.assertIn("Spider closed (finished)", log)
+        self.assertIn("Using reactor: twisted.internet.asyncioreactor.AsyncioSelectorReactor", log)
+
+    # https://twistedmatrix.com/trac/ticket/9766
+    @skipIf(platform.system() == 'Windows' and sys.version_info >= (3, 8),
+            "the asyncio reactor is broken on Windows when running Python ≥ 3.8")
+    def test_reactor_asyncio_custom_settings_conflict(self):
+        log = self.run_script("twisted_reactor_custom_settings_conflict.py")
+        self.assertIn("Using reactor: twisted.internet.pollreactor.PollReactor", log)
+        self.assertIn("(twisted.internet.pollreactor.PollReactor) does not match the requested one", log)
+
     @mark.skipif(sys.implementation.name == 'pypy', reason='uvloop does not support pypy properly')
     @mark.skipif(platform.system() == 'Windows', reason='uvloop does not support Windows')
     @mark.skipif(twisted_version == Version('twisted', 21, 2, 0), reason='https://twistedmatrix.com/trac/ticket/10106')