Fix tests if HOME environment is missing

- fixes #870

4 files changed, 43 insertions, 26 deletions

diff --git a/CHANGES.md b/CHANGES.md
index d40fcac..6e20517 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -5,6 +5,7 @@ The released versions correspond to PyPI releases.
 
 ### Fixes
 * removed a leftover debug print statement (see [#869](../../issues/869))
+* make sure tests work without HOME environment set (see [#870](../../issues/870))
 
 ## [Version 5.2.3](https://pypi.python.org/pypi/pyfakefs/5.2.3) (2023-08-18)
 Fixes a rare problem on pytest shutdown.
diff --git a/pyfakefs/tests/fake_filesystem_test.py b/pyfakefs/tests/fake_filesystem_test.py
index dda4638..696f8a8 100644
--- a/pyfakefs/tests/fake_filesystem_test.py
+++ b/pyfakefs/tests/fake_filesystem_test.py
@@ -20,6 +20,7 @@ import os
 import stat
 import sys
 import unittest
+from unittest.mock import patch
 
 from pyfakefs import fake_filesystem, fake_os, fake_open
 from pyfakefs.fake_filesystem import (
@@ -1061,17 +1062,22 @@ class FakePathModuleTest(TestCase):
         components = [b"foo", b"bar", b"baz"]
         self.assertEqual(b"foo!bar!baz", self.path.join(*components))
 
+    @unittest.skipIf(sys.platform != "win32", "Windows specific test")
+    @patch.dict(os.environ, {"USERPROFILE": r"C:\Users\John"})
+    def test_expand_user_windows(self):
+        self.assertEqual(self.path.expanduser("~"), "C:!Users!John")
+
+    @unittest.skipIf(sys.platform == "win32", "Posix specific test")
+    @patch.dict(os.environ, {"HOME": "/home/john"})
     def test_expand_user(self):
-        if self.is_windows:
-            self.assertEqual(
-                self.path.expanduser("~"),
-                self.os.environ["USERPROFILE"].replace("\\", "!"),
-            )
-        else:
-            self.assertEqual(
-                self.path.expanduser("~"),
-                self.os.environ["HOME"].replace("/", "!"),
-            )
+        self.assertEqual(self.path.expanduser("~"), "!home!john")
+
+    @patch.dict(os.environ, {}, clear=True)
+    def test_expand_user_no_home_environment(self):
+        """Make sure this also works without HOME / USERPROFILE set"""
+        # we just check that it does not crash and has some result,
+        # as the result is system-dependent
+        self.assertTrue(self.path.expanduser("~"))
 
     @unittest.skipIf(
         TestCase.is_windows or TestCase.is_cygwin,
diff --git a/pyfakefs/tests/fake_filesystem_unittest_test.py b/pyfakefs/tests/fake_filesystem_unittest_test.py
index 6d3e6e6..86f1ae6 100644
--- a/pyfakefs/tests/fake_filesystem_unittest_test.py
+++ b/pyfakefs/tests/fake_filesystem_unittest_test.py
@@ -815,6 +815,7 @@ class TestOtherFS(fake_filesystem_unittest.TestCase):
     def setUp(self):
         self.setUpPyfakefs()
 
+    @mock.patch.dict(os.environ, {"HOME": "/home/john"})
     def test_real_file_with_home(self):
         """Regression test for #558"""
         self.fs.is_windows_fs = os.name != "nt"
diff --git a/pyfakefs/tests/fake_pathlib_test.py b/pyfakefs/tests/fake_pathlib_test.py
index d487f32..12820ba 100644
--- a/pyfakefs/tests/fake_pathlib_test.py
+++ b/pyfakefs/tests/fake_pathlib_test.py
@@ -27,6 +27,7 @@ import sys
 import unittest
 from collections import namedtuple
 from unittest import mock
+from unittest.mock import patch
 
 from pyfakefs import fake_pathlib, fake_filesystem, fake_filesystem_unittest, fake_os
 from pyfakefs.fake_filesystem import OSType
@@ -461,23 +462,31 @@ class FakePathlibFileObjectPropertyTest(RealPathlibTestCase):
             self.path.cwd(), self.path(self.os.path.realpath(dir_path))
         )
 
-    def test_expanduser(self):
-        if is_windows:
-            self.assertEqual(
-                self.path("~").expanduser(),
-                self.path(os.environ["USERPROFILE"].replace("\\", "/")),
-            )
-        else:
-            self.assertEqual(self.path("~").expanduser(), self.path(os.environ["HOME"]))
+    @unittest.skipIf(sys.platform != "win32", "Windows specific test")
+    @patch.dict(os.environ, {"USERPROFILE": r"C:\Users\John"})
+    def test_expanduser_windows(self):
+        self.assertEqual(
+            self.path("~").expanduser(),
+            self.path("C:/Users/John"),
+        )
 
-    def test_home(self):
-        if is_windows:
-            self.assertEqual(
-                self.path(os.environ["USERPROFILE"].replace("\\", "/")),
-                self.path.home(),
-            )
-        else:
-            self.assertEqual(self.path(os.environ["HOME"]), self.path.home())
+    @unittest.skipIf(sys.platform == "win32", "Posix specific test")
+    @patch.dict(os.environ, {"HOME": "/home/john"})
+    def test_expanduser_posix(self):
+        self.assertEqual(self.path("~").expanduser(), self.path("/home/john"))
+
+    @unittest.skipIf(sys.platform != "win32", "Windows specific test")
+    @patch.dict(os.environ, {"USERPROFILE": r"C:\Users\John"})
+    def test_home_windows(self):
+        self.assertEqual(
+            self.path(self.path("C:/Users/John")),
+            self.path.home(),
+        )
+
+    @unittest.skipIf(sys.platform == "win32", "Posix specific test")
+    @patch.dict(os.environ, {"HOME": "/home/john"})
+    def test_home_posix(self):
+        self.assertEqual(self.path("/home/john"), self.path.home())
 
 
 class RealPathlibFileObjectPropertyTest(FakePathlibFileObjectPropertyTest):