add some test for legacy tester

tests/util/test_testing.py

@@ -0,0 +1,45 @@
+"""Test testing utils."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from pymatgen.core import Element, Structure
+from pymatgen.io.vasp.inputs import Kpoints
+from pymatgen.util.testing import PymatgenTest
+
+
+class TestPymatgenTest(PymatgenTest):
+    def test_deprecated(self):
+        pass
+
+    def test_tmp_dir(self):
+        current_dir = Path.cwd()
+        assert current_dir == self.tmp_path
+
+        assert self.tmp_path.is_dir()
+
+        test_file = self.tmp_path / "test_file.txt"
+        test_file.write_text("Hello, pytest!")
+
+        assert test_file.exists()
+        assert test_file.read_text() == "Hello, pytest!"
+
+    def test_get_structure(self):
+        assert isinstance(self.get_structure("LiFePO4"), Structure)
+
+    def test_assert_str_content_equal(self):
+        # TODO: see PR 4205, assert_str_content_equal has a minor bug
+        # and would not raise AssertError but return a boolean only
+        assert self.assert_str_content_equal("hi", " hi")
+        assert not self.assert_str_content_equal("hi", "world")
+
+    def test_serialize_with_pickle(self):
+        result = self.serialize_with_pickle(Element.from_Z(1))
+        assert isinstance(result, list)
+        assert result[0] is Element.H
+
+    def test_assert_msonable(self):
+        kpoints = Kpoints.gamma_automatic((3, 3, 3), [0, 0, 0])
+        kp_str = self.assert_msonable(kpoints)
+        assert "Automatic kpoint scheme" in kp_str