Fix limiting subprocess run time in tests. (#6933)

* Fix limiting subprocess run time in tests.

* Make test_runspider_dnscache_disabled() faster.

tests/test_command_runspider.py

@@ -112,6 +112,11 @@ class MySpider(scrapy.Spider):
     name = 'myspider'
     start_urls = ['http://localhost:12345']
 
+    custom_settings = {
+        "ROBOTSTXT_OBEY": False,
+        "RETRY_ENABLED": False,
+    }
+
     def parse(self, response):
         return {'test': 'value'}
 """

tests/test_commands.py

@@ -9,10 +9,11 @@ from io import StringIO
 from pathlib import Path
 from shutil import rmtree
 from tempfile import TemporaryFile, mkdtemp
-from threading import Timer
 from typing import TYPE_CHECKING, Any
 from unittest import mock
 
+import pytest
+
 import scrapy
 from scrapy.cmdline import _pop_command_name, _print_unknown_command_msg
 from scrapy.commands import ScrapyCommand, ScrapyHelpFormatter, view
@@ -100,17 +101,12 @@ class TestProjectBase:
             **popen_kwargs,
         )
 
-        def kill_proc():
+        try:
+            stdout, stderr = p.communicate(timeout=15)
+        except subprocess.TimeoutExpired:
             p.kill()
             p.communicate()
-            raise AssertionError("Command took too much time to complete")
-
-        timer = Timer(15, kill_proc)
-        try:
-            timer.start()
-            stdout, stderr = p.communicate()
-        finally:
-            timer.cancel()
+            pytest.fail("Command took too much time to complete")
 
         return p, to_unicode(stdout), to_unicode(stderr)
 

tests/test_engine.py

@@ -17,7 +17,6 @@ from collections import defaultdict
 from dataclasses import dataclass
 from logging import DEBUG
 from pathlib import Path
-from threading import Timer
 from unittest.mock import Mock
 from urllib.parse import urlparse
 
@@ -495,17 +494,12 @@ class TestEngine(TestEngineBase):
             stderr=subprocess.PIPE,
         )
 
-        def kill_proc():
+        try:
+            _, stderr = p.communicate(timeout=3)
+        except subprocess.TimeoutExpired:
             p.kill()
             p.communicate()
-            raise AssertionError("Command took too much time to complete")
-
-        timer = Timer(15, kill_proc)
-        try:
-            timer.start()
-            _, stderr = p.communicate()
-        finally:
-            timer.cancel()
+            pytest.fail("Command took too much time to complete")
 
         stderr_str = stderr.decode("utf-8")
         assert "AttributeError" not in stderr_str, stderr_str