From ac7f7eab0fad18fffc465bc4fdc092bcb2de2d80 Mon Sep 17 00:00:00 2001
From: Tom Forbes <tom@tomforb.es>
Date: Thu, 18 Jun 2020 12:04:10 +0100
Subject: [PATCH] [3.1.x] Fixed #31716 -- Fixed detection of console scripts in
 autoreloader on Windows.

Backport of 8a902b7ee622ada258d15fb122092c1f02b82698 from master
---
 django/utils/autoreload.py           | 16 ++++++++-
 tests/utils_tests/test_autoreload.py | 53 ++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/django/utils/autoreload.py b/django/utils/autoreload.py
index 845c46c8d44..1ef10a15f92 100644
--- a/django/utils/autoreload.py
+++ b/django/utils/autoreload.py
@@ -207,12 +207,26 @@ def get_child_arguments():
     on reloading.
     """
     import django.__main__
+    django_main_path = Path(django.__main__.__file__)
+    py_script = Path(sys.argv[0])
 
     args = [sys.executable] + ['-W%s' % o for o in sys.warnoptions]
-    if sys.argv[0] == django.__main__.__file__:
+    if py_script == django_main_path:
         # The server was started with `python -m django runserver`.
         args += ['-m', 'django']
         args += sys.argv[1:]
+    elif not py_script.exists():
+        # sys.argv[0] may not exist for several reasons on Windows.
+        # It may exist with a .exe extension or have a -script.py suffix.
+        exe_entrypoint = py_script.with_suffix('.exe')
+        if exe_entrypoint.exists():
+            # Should be executed directly, ignoring sys.executable.
+            return [exe_entrypoint, *sys.argv[1:]]
+        script_entrypoint = py_script.with_name('%s-script.py' % py_script.name)
+        if script_entrypoint.exists():
+            # Should be executed as usual.
+            return [*args, script_entrypoint, *sys.argv[1:]]
+        raise RuntimeError('Script %s does not exist.' % py_script)
     else:
         args += sys.argv
     return args
diff --git a/tests/utils_tests/test_autoreload.py b/tests/utils_tests/test_autoreload.py
index 09656b8599e..f4ecb387777 100644
--- a/tests/utils_tests/test_autoreload.py
+++ b/tests/utils_tests/test_autoreload.py
@@ -14,6 +14,7 @@ from pathlib import Path
 from subprocess import CompletedProcess
 from unittest import mock, skip, skipIf
 
+import django.__main__
 from django.apps.registry import Apps
 from django.test import SimpleTestCase
 from django.test.utils import extend_sys_path
@@ -153,6 +154,55 @@ class TestIterModulesAndFiles(SimpleTestCase):
                 )
 
 
+class TestChildArguments(SimpleTestCase):
+    @mock.patch('sys.argv', [django.__main__.__file__, 'runserver'])
+    @mock.patch('sys.warnoptions', [])
+    def test_run_as_module(self):
+        self.assertEqual(
+            autoreload.get_child_arguments(),
+            [sys.executable, '-m', 'django', 'runserver']
+        )
+
+    @mock.patch('sys.argv', [__file__, 'runserver'])
+    @mock.patch('sys.warnoptions', ['error'])
+    def test_warnoptions(self):
+        self.assertEqual(
+            autoreload.get_child_arguments(),
+            [sys.executable, '-Werror', __file__, 'runserver']
+        )
+
+    @mock.patch('sys.warnoptions', [])
+    def test_exe_fallback(self):
+        tmpdir = tempfile.TemporaryDirectory()
+        self.addCleanup(tmpdir.cleanup)
+        exe_path = Path(tmpdir.name) / 'django-admin.exe'
+        exe_path.touch()
+        with mock.patch('sys.argv', [exe_path.with_suffix(''), 'runserver']):
+            self.assertEqual(
+                autoreload.get_child_arguments(),
+                [exe_path, 'runserver']
+            )
+
+    @mock.patch('sys.warnoptions', [])
+    def test_entrypoint_fallback(self):
+        tmpdir = tempfile.TemporaryDirectory()
+        self.addCleanup(tmpdir.cleanup)
+        script_path = Path(tmpdir.name) / 'django-admin-script.py'
+        script_path.touch()
+        with mock.patch('sys.argv', [script_path.with_name('django-admin'), 'runserver']):
+            self.assertEqual(
+                autoreload.get_child_arguments(),
+                [sys.executable, script_path, 'runserver']
+            )
+
+    @mock.patch('sys.argv', ['does-not-exist', 'runserver'])
+    @mock.patch('sys.warnoptions', [])
+    def test_raises_runtimeerror(self):
+        msg = 'Script does-not-exist does not exist.'
+        with self.assertRaisesMessage(RuntimeError, msg):
+            autoreload.get_child_arguments()
+
+
 class TestCommonRoots(SimpleTestCase):
     def test_common_roots(self):
         paths = (
@@ -360,6 +410,9 @@ class RestartWithReloaderTests(SimpleTestCase):
         return mock_call
 
     def test_manage_py(self):
+        script = Path('manage.py')
+        script.touch()
+        self.addCleanup(script.unlink)
         argv = ['./manage.py', 'runserver']
         mock_call = self.patch_autoreload(argv)
         autoreload.restart_with_reloader()