From 126896f69d065b46efbf55e6e2b30865ab4569c0 Mon Sep 17 00:00:00 2001
From: Virgil Dupras <hsoft@hardcoded.net>
Date: Mon, 6 Aug 2018 16:17:24 -0400
Subject: [PATCH] Add option to disable plugin auto-loading

If `PYTEST_DISABLE_PLUGIN_AUTOLOAD` is set, disable auto-loading of
plugins through setuptools entrypoints. Only plugins that have been
explicitly specified are loaded.

ref #3784.
---
 AUTHORS                        |  1 +
 changelog/3784.feature.rst     |  1 +
 doc/en/reference.rst           |  5 +++++
 src/_pytest/config/__init__.py |  9 ++++++++-
 src/_pytest/helpconfig.py      |  1 +
 testing/test_config.py         | 20 ++++++++++++++++++++
 6 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 changelog/3784.feature.rst

diff --git a/AUTHORS b/AUTHORS
index 49440194e..3b0448371 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -207,6 +207,7 @@ Tzu-ping Chung
 Vasily Kuznetsov
 Victor Uriarte
 Vidar T. Fauske
+Virgil Dupras
 Vitaly Lashmanov
 Vlad Dragos
 Wil Cooley
diff --git a/changelog/3784.feature.rst b/changelog/3784.feature.rst
new file mode 100644
index 000000000..87b6cafb6
--- /dev/null
+++ b/changelog/3784.feature.rst
@@ -0,0 +1 @@
+Add option to disable plugin auto-loading.
diff --git a/doc/en/reference.rst b/doc/en/reference.rst
index 86d92cf07..6e235e176 100644
--- a/doc/en/reference.rst
+++ b/doc/en/reference.rst
@@ -866,6 +866,11 @@ Contains comma-separated list of modules that should be loaded as plugins:
 
     export PYTEST_PLUGINS=mymodule.plugin,xdist
 
+PYTEST_DISABLE_PLUGIN_AUTOLOAD
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When set, disables plugin auto-loading through setuptools entrypoints. Only explicitly specified plugins will be
+loaded.
 
 PYTEST_CURRENT_TEST
 ~~~~~~~~~~~~~~~~~~~
diff --git a/src/_pytest/config/__init__.py b/src/_pytest/config/__init__.py
index 421d124e9..3b2d622c3 100644
--- a/src/_pytest/config/__init__.py
+++ b/src/_pytest/config/__init__.py
@@ -701,6 +701,10 @@ class Config(object):
 
         self.pluginmanager.rewrite_hook = hook
 
+        if os.environ.get("PYTEST_DISABLE_PLUGIN_AUTOLOAD"):
+            # We don't autoload from setuptools entry points, no need to continue.
+            return
+
         # 'RECORD' available for plugins installed normally (pip install)
         # 'SOURCES.txt' available for plugins installed in dev mode (pip install -e)
         # for installed plugins 'SOURCES.txt' returns an empty list, and vice-versa
@@ -726,7 +730,10 @@ class Config(object):
         self._checkversion()
         self._consider_importhook(args)
         self.pluginmanager.consider_preparse(args)
-        self.pluginmanager.load_setuptools_entrypoints("pytest11")
+        if not os.environ.get("PYTEST_DISABLE_PLUGIN_AUTOLOAD"):
+            # Don't autoload from setuptools entry point. Only explicitly specified
+            # plugins are going to be loaded.
+            self.pluginmanager.load_setuptools_entrypoints("pytest11")
         self.pluginmanager.consider_env()
         self.known_args_namespace = ns = self._parser.parse_known_args(
             args, namespace=copy.copy(self.option)
diff --git a/src/_pytest/helpconfig.py b/src/_pytest/helpconfig.py
index 12c3339c6..85f071e9e 100644
--- a/src/_pytest/helpconfig.py
+++ b/src/_pytest/helpconfig.py
@@ -156,6 +156,7 @@ 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_DEBUG", "set to enable debug tracing of pytest's internals"),
     ]
     for name, help in vars:
diff --git a/testing/test_config.py b/testing/test_config.py
index b507bb8e8..d58bda255 100644
--- a/testing/test_config.py
+++ b/testing/test_config.py
@@ -605,6 +605,26 @@ def test_plugin_preparse_prevents_setuptools_loading(testdir, monkeypatch, block
         )
 
 
+@pytest.mark.parametrize(
+    "parse_args,should_load", [(("-p", "mytestplugin"), True), ((), False)]
+)
+def test_disable_plugin_autoload(testdir, monkeypatch, 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")
+    monkeypatch.setattr(pkg_resources, "iter_entry_points", my_iter)
+    monkeypatch.setitem(sys.modules, "mytestplugin", PseudoPlugin())
+    config = testdir.parseconfig(*parse_args)
+    has_loaded = config.pluginmanager.get_plugin("mytestplugin") is not None
+    assert has_loaded == should_load
+
+
 def test_cmdline_processargs_simple(testdir):
     testdir.makeconftest(
         """