PYTEST_DISABLE_PLUGIN_AUTOLOAD: allow 0 to enable it explicitly

doc/en/reference.rst

@@ -878,8 +878,8 @@ Contains comma-separated list of modules that should be loaded as plugins:
 PYTEST_DISABLE_PLUGIN_AUTOLOAD
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-When set, disables plugin auto-loading through setuptools entrypoints. Only explicitly specified plugins will be
-loaded.
+Set to "1" to disable plugin auto-loading through setuptools entrypoints.
+Only explicitly specified plugins will be loaded then.
 
 PYTEST_CURRENT_TEST
 ~~~~~~~~~~~~~~~~~~~

src/_pytest/config/__init__.py

@@ -757,7 +757,7 @@ def _mark_plugins_for_rewrite(self, hook):
 
         self.pluginmanager.rewrite_hook = hook
 
-        if os.environ.get("PYTEST_DISABLE_PLUGIN_AUTOLOAD"):
+        if bool(int(os.environ.get("PYTEST_DISABLE_PLUGIN_AUTOLOAD", "0"))):
             # We don't autoload from setuptools entry points, no need to continue.
             return
 
@@ -786,7 +786,7 @@ def _preparse(self, args, addopts=True):
         self._checkversion()
         self._consider_importhook(args)
         self.pluginmanager.consider_preparse(args)
-        if not os.environ.get("PYTEST_DISABLE_PLUGIN_AUTOLOAD"):
+        if not bool(int(os.environ.get("PYTEST_DISABLE_PLUGIN_AUTOLOAD", "0"))):
             # Don't autoload from setuptools entry point. Only explicitly specified
             # plugins are going to be loaded.
             self.pluginmanager.load_setuptools_entrypoints("pytest11")

src/_pytest/helpconfig.py

@@ -160,7 +160,7 @@ def showhelp(config):
     vars = [
         ("PYTEST_ADDOPTS", "extra command line options"),
         ("PYTEST_PLUGINS", "comma-separated plugins to load during startup"),
-        ("PYTEST_DISABLE_PLUGIN_AUTOLOAD", "set to disable plugin auto-loading"),
+        ("PYTEST_DISABLE_PLUGIN_AUTOLOAD", 'set to "1" to disable plugin auto-loading'),
         ("PYTEST_DEBUG", "set to enable debug tracing of pytest's internals"),
     ]
     for name, help in vars:

testing/test_config.py

@@ -612,18 +612,36 @@ def load(self):
 
 
 @pytest.mark.parametrize(
-    "parse_args,should_load", [(("-p", "mytestplugin"), True), ((), False)]
+    "env,parse_args,should_load",
+    [("1", ("-p", "mytestplugin"), True), ("1", (), False), ("0", (), True)],
 )
-def test_disable_plugin_autoload(testdir, monkeypatch, parse_args, should_load):
+def test_disable_plugin_autoload(testdir, monkeypatch, env, parse_args, should_load):
     pkg_resources = pytest.importorskip("pkg_resources")
 
-    def my_iter(name):
-        raise AssertionError("Should not be called")
-
     class PseudoPlugin(object):
         x = 42
 
-    monkeypatch.setenv("PYTEST_DISABLE_PLUGIN_AUTOLOAD", "1")
+    def my_iter(name):
+        if env == "1":
+            raise AssertionError("Should not be called")
+
+        class Dist(object):
+            project_name = "spam"
+            version = "1.0"
+
+            def _get_metadata(self, name):
+                return ["foo.txt,sha256=abc,123"]
+
+        class EntryPoint(object):
+            name = "mytestplugin"
+            dist = Dist()
+
+            def load(self):
+                return PseudoPlugin()
+
+        return iter([EntryPoint()])
+
+    monkeypatch.setenv("PYTEST_DISABLE_PLUGIN_AUTOLOAD", env)
     monkeypatch.setattr(pkg_resources, "iter_entry_points", my_iter)
     monkeypatch.setitem(sys.modules, "mytestplugin", PseudoPlugin())
     config = testdir.parseconfig(*parse_args)