Add support for with_suffix in Path

elements/path.py

@@ -106,6 +106,10 @@ def write_text(self, content):
   def write_bytes(self, content):
     self.write(content, mode='wb')
 
+  def with_suffix(self, suffix):
+    path = str(self.parent / self.stem) + suffix
+    return type(self)(path)
+
   def open(self, mode='r'):
     raise NotImplementedError
 

tests/test_path.py

@@ -39,3 +39,14 @@ def test_parent(self):
     assert (empty / 'foo' / 'bar.txt').parent.parent == empty
     assert root.parent == root
     assert empty.parent == empty
+
+  def test_with_suffix(self):
+    examples = [
+        ('foo.a', '.b', 'foo.b'),
+        ('foo/bar.a.b', '.c', 'foo/bar.c'),
+        ('foo', '.abc', 'foo.abc'),
+        ('foo.xyz', '', 'foo'),
+        ('foo', '', 'foo'),
+    ]
+    for path, suffix, output in examples:
+      assert str(elements.Path(path).with_suffix(suffix)) == output