pathlib: add Path.expanduser()

Signed-off-by: Michael Hirsch <michael@scivision.dev>

python-stdlib/pathlib/pathlib.py

@@ -184,6 +184,13 @@ class Path:
         index = -len(self.suffix) or None
         return Path(self._path[:index] + suffix)
 
+    def expanduser(self):
+        if self._path == "~" or self._path.startswith("~" + _SEP):
+            return Path(os.getenv("HOME") + self._path[1:])
+        if self._path[0] == "~":
+            raise RuntimeError("User home directory expansion not supported.")
+        return self
+
     @property
     def stem(self):
         return self.name.rsplit(".", 1)[0]

python-stdlib/pathlib/tests/test_pathlib.py

@@ -322,3 +322,11 @@ class TestPathlib(unittest.TestCase):
         self.assertTrue(Path("foo/test").with_suffix(".tar") == Path("foo/test.tar"))
         self.assertTrue(Path("foo/bar.bin").with_suffix(".txt") == Path("foo/bar.txt"))
         self.assertTrue(Path("bar.txt").with_suffix("") == Path("bar"))
+
+    def test_expanduser(self):
+        self.assertFalse(str(Path("~").expanduser()) == "~")
+        self.assertTrue(str(Path("~").expanduser()) == os.getenv("HOME"))
+        self.assertTrue(str(Path("~/foo").expanduser()) == os.getenv("HOME") + "/foo")
+
+        with self.assertRaises(RuntimeError):
+            Path("~foo").expanduser()