[meld/pathlabel] test: Add coverage for shared parent being the root

[Kai Willadsen <kaiw src gnome org>]

commit 61040188870b2465230def4e47bc57ca8169930a
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Aug 15 08:31:59 2021 +1000

    test: Add coverage for shared parent being the root

 test/test_iohelpers.py | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/test/test_iohelpers.py b/test/test_iohelpers.py
index 5171253e..9c1437f5 100644
--- a/test/test_iohelpers.py
+++ b/test/test_iohelpers.py
@@ -45,6 +45,12 @@ def test_find_shared_parent_path(paths, expected_parent):
             '/home/hey/foo.txt',
             '…/foo.txt',
         ),
+        # Child is a direct child of parent and parent is the root
+        (
+            '/',
+            '/foo.txt',
+            '/foo.txt',
+        ),
         # Child is a 2-depth child of parent
         (
             '/home/hey/',