bpo-10496: posixpath.expanduser() catchs pwd.getpwuid() error (GH-10919) (GH-10925)

* posixpath.expanduser() now returns the input path unchanged if
  the HOME environment variable is not set and pwd.getpwuid() raises
  KeyError (the current user identifier doesn't exist in the password
  database).
* Add test_no_home_directory() to test_site.

(cherry picked from commit f2f4555d8287ad217a1dba7bbd93103ad4daf3a8)

1 files changed, 49 insertions, 29 deletions

diff --git a/Lib/test/test_posixpath.py b/Lib/test/test_posixpath.py
index 9476ede..e73b31c 100644
--- a/Lib/test/test_posixpath.py
+++ b/Lib/test/test_posixpath.py
@@ -5,6 +5,7 @@ import warnings
 from posixpath import realpath, abspath, dirname, basename
 from test import support, test_genericpath
 from test.support import FakePath
+from unittest import mock
 
 try:
     import posix
@@ -230,42 +231,61 @@ class PosixPathTest(unittest.TestCase):
     def test_expanduser(self):
         self.assertEqual(posixpath.expanduser("foo"), "foo")
         self.assertEqual(posixpath.expanduser(b"foo"), b"foo")
+
+    def test_expanduser_home_envvar(self):
         with support.EnvironmentVarGuard() as env:
+            env['HOME'] = '/home/victor'
+            self.assertEqual(posixpath.expanduser("~"), "/home/victor")
+
+            # expanduser() strips trailing slash
+            env['HOME'] = '/home/victor/'
+            self.assertEqual(posixpath.expanduser("~"), "/home/victor")
+
             for home in '/', '', '//', '///':
                 with self.subTest(home=home):
                     env['HOME'] = home
                     self.assertEqual(posixpath.expanduser("~"), "/")
                     self.assertEqual(posixpath.expanduser("~/"), "/")
                     self.assertEqual(posixpath.expanduser("~/foo"), "/foo")
-        try:
-            import pwd
-        except ImportError:
-            pass
-        else:
-            self.assertIsInstance(posixpath.expanduser("~/"), str)
-            self.assertIsInstance(posixpath.expanduser(b"~/"), bytes)
-            # if home directory == root directory, this test makes no sense
-            if posixpath.expanduser("~") != '/':
-                self.assertEqual(
-                    posixpath.expanduser("~") + "/",
-                    posixpath.expanduser("~/")
-                )
-                self.assertEqual(
-                    posixpath.expanduser(b"~") + b"/",
-                    posixpath.expanduser(b"~/")
-                )
-            self.assertIsInstance(posixpath.expanduser("~root/"), str)
-            self.assertIsInstance(posixpath.expanduser("~foo/"), str)
-            self.assertIsInstance(posixpath.expanduser(b"~root/"), bytes)
-            self.assertIsInstance(posixpath.expanduser(b"~foo/"), bytes)
-
-            with support.EnvironmentVarGuard() as env:
-                # expanduser should fall back to using the password database
-                del env['HOME']
-                home = pwd.getpwuid(os.getuid()).pw_dir
-                # $HOME can end with a trailing /, so strip it (see #17809)
-                home = home.rstrip("/") or '/'
-                self.assertEqual(posixpath.expanduser("~"), home)
+
+    def test_expanduser_pwd(self):
+        pwd = support.import_module('pwd')
+
+        self.assertIsInstance(posixpath.expanduser("~/"), str)
+        self.assertIsInstance(posixpath.expanduser(b"~/"), bytes)
+
+        # if home directory == root directory, this test makes no sense
+        if posixpath.expanduser("~") != '/':
+            self.assertEqual(
+                posixpath.expanduser("~") + "/",
+                posixpath.expanduser("~/")
+            )
+            self.assertEqual(
+                posixpath.expanduser(b"~") + b"/",
+                posixpath.expanduser(b"~/")
+            )
+        self.assertIsInstance(posixpath.expanduser("~root/"), str)
+        self.assertIsInstance(posixpath.expanduser("~foo/"), str)
+        self.assertIsInstance(posixpath.expanduser(b"~root/"), bytes)
+        self.assertIsInstance(posixpath.expanduser(b"~foo/"), bytes)
+
+        with support.EnvironmentVarGuard() as env:
+            # expanduser should fall back to using the password database
+            del env['HOME']
+
+            home = pwd.getpwuid(os.getuid()).pw_dir
+            # $HOME can end with a trailing /, so strip it (see #17809)
+            home = home.rstrip("/") or '/'
+            self.assertEqual(posixpath.expanduser("~"), home)
+
+            # bpo-10496: If the HOME environment variable is not set and the
+            # user (current identifier or name in the path) doesn't exist in
+            # the password database (pwd.getuid() or pwd.getpwnam() fail),
+            # expanduser() must return the path unchanged.
+            with mock.patch.object(pwd, 'getpwuid', side_effect=KeyError), \
+                 mock.patch.object(pwd, 'getpwnam', side_effect=KeyError):
+                for path in ('~', '~/.local', '~vstinner/'):
+                    self.assertEqual(posixpath.expanduser(path), path)
 
     def test_normpath(self):
         self.assertEqual(posixpath.normpath(""), ".")