Add test_bad_argv0_posix

Signed-off-by: Filipe Laíns <lains@riseup.net>

Author: FFY00

Lib/test/test_getpath.py

@@ -497,6 +497,34 @@ def test_symlink_normal_posix(self):
         actual = getpath(ns, expected)
         self.assertEqual(expected, actual)
 
+    def test_bad_argv0_posix(self):
+        """Test that executable resolves correctly if argv0 is not Python and we
+        know real_executable (getpath.c computes it from readlink(/proc/self/exe)).
+        """
+        ns = MockPosixNamespace(
+            PREFIX="/usr",
+            argv0="not-python",
+            real_executable="/usr/bin/python",
+        )
+        ns.add_known_xfile("/usr/bin/python")
+        ns.add_known_file("/usr/lib/python9.8/os.py")
+        ns.add_known_dir("/usr/lib/python9.8/lib-dynload")
+        expected = dict(
+            executable="/usr/bin/python",
+            base_executable="/usr/bin/python",
+            prefix="/usr",
+            exec_prefix="/usr",
+            module_search_paths_set=1,
+            module_search_paths=[
+                "/usr/lib/python98.zip",
+                "/usr/lib/python9.8",
+                "/usr/lib/python9.8/lib-dynload",
+            ],
+        )
+        actual = getpath(ns, expected)
+        self.assertEqual(expected, actual)
+
+
     def test_symlink_buildpath_posix(self):
         """Test an in-build-tree layout on POSIX.