Issue #16309: Make PYTHONPATH= behavior the same as if PYTHONPATH not set at all.

Thanks to Armin Rigo and Alexey Kachayev.

1 files changed, 17 insertions, 0 deletions

diff --git a/Lib/test/test_cmd_line.py b/Lib/test/test_cmd_line.py
index 7644db2..cbe1e55 100644
--- a/Lib/test/test_cmd_line.py
+++ b/Lib/test/test_cmd_line.py
@@ -216,6 +216,23 @@ class CmdLineTest(unittest.TestCase):
         self.assertIn(path1.encode('ascii'), out)
         self.assertIn(path2.encode('ascii'), out)
 
+    def test_empty_PYTHONPATH_issue16309(self):
+        """On Posix, it is documented that setting PATH to the
+        empty string is equivalent to not setting PATH at all,
+        which is an exception to the rule that in a string like
+        "/bin::/usr/bin" the empty string in the middle gets
+        interpreted as '.'"""
+        code = """if 1:
+            import sys
+            path = ":".join(sys.path)
+            path = path.encode("ascii", "backslashreplace")
+            sys.stdout.buffer.write(path)"""
+        rc1, out1, err1 = assert_python_ok('-c', code, PYTHONPATH="")
+        rc2, out2, err2 = assert_python_ok('-c', code)
+        # regarding to Posix specification, outputs should be equal
+        # for empty and unset PYTHONPATH
+        self.assertEquals(out1, out2)
+
     def test_displayhook_unencodable(self):
         for encoding in ('ascii', 'latin-1', 'utf-8'):
             env = os.environ.copy()