[meld/pathlabel] test: Add test coverage for `find_shared_parent_path()`

[Kai Willadsen <kaiw src gnome org>]

commit 8d89a898af1fef5777fda53e6a746890bad5c405
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Wed Jan 13 07:23:59 2021 +1000

    test: Add test coverage for `find_shared_parent_path()`

 test/test_iohelpers.py | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
---
diff --git a/test/test_iohelpers.py b/test/test_iohelpers.py
new file mode 100644
index 00000000..db540e79
--- /dev/null
+++ b/test/test_iohelpers.py
@@ -0,0 +1,36 @@
+
+import pytest
+from gi.repository import Gio
+
+from meld.iohelpers import find_shared_parent_path
+
+
+@pytest.mark.parametrize(
+    'paths, expected_parent',
+    [
+        # No paths, None return
+        ([], None),
+        # One path always returns its own parent
+        (['/foo/a/b/c'], '/foo/a/b'),
+        # Two paths
+        (['/foo/a', '/foo/b'], '/foo'),
+        # Three paths
+        (['/foo/a', '/foo/b', '/foo/c'], '/foo'),
+        # First path is deeper
+        (['/foo/a/asd/asd', '/foo/b'], '/foo'),
+        # Second path is deeper
+        (['/foo/a/', '/foo/b/asd/asd'], '/foo'),
+        # Common parent is the root
+        (['/foo/a/', '/bar/b/'], '/'),
+    ],
+)
+def test_find_shared_parent_path(paths, expected_parent):
+    files = [Gio.File.new_for_path(p) for p in paths]
+    print([f.get_path() for f in files])
+    parent = find_shared_parent_path(files)
+
+    if parent is None:
+        assert expected_parent is None
+    else:
+        print(f'Parent: {parent.get_path()}; expected {expected_parent}')
+        assert parent.equal(Gio.File.new_for_path(expected_parent))