testing/conftest.py: testdir: set PYTEST_DISABLE_PLUGIN_AUTOLOAD=1

Fixes pytest-dev#4518.

Author: blueyed

testing/conftest.py

@@ -2,6 +2,7 @@
 import sys
 
 import pytest
+from _pytest.pytester import Testdir
 
 
 def pytest_addoption(parser):
@@ -152,3 +153,9 @@ def runtest(self):
     """
     )
     testdir.makefile(".yaml", test1="")
+
+
+@pytest.fixture
+def testdir(testdir: Testdir) -> Testdir:
+    testdir.monkeypatch.setenv("PYTEST_DISABLE_PLUGIN_AUTOLOAD", "1")
+    return testdir

testing/test_junitxml.py

@@ -1226,6 +1226,7 @@ def test_pass():
 
 
 def test_runs_twice_xdist(testdir, run_and_parse):
+    testdir.monkeypatch.delenv("PYTEST_DISABLE_PLUGIN_AUTOLOAD")
     pytest.importorskip("xdist")
     testdir.monkeypatch.delenv("PYTEST_DISABLE_PLUGIN_AUTOLOAD")
     f = testdir.makepyfile(

testing/test_terminal.py

@@ -714,6 +714,7 @@ def test_verbose_reporting(self, verbose_testfile, testdir):
         assert result.ret == 1
 
     def test_verbose_reporting_xdist(self, verbose_testfile, testdir, pytestconfig):
+        testdir.monkeypatch.delenv("PYTEST_DISABLE_PLUGIN_AUTOLOAD")
         if not pytestconfig.pluginmanager.get_plugin("xdist"):
             pytest.skip("xdist plugin not installed")