test: mixed data format: test if the index_map (when type_map is provided) works (#706)

consider the PR after #705 

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- Enhanced testing framework for multi-system comparisons, allowing for
dynamic generation of test functions and classes.
- Introduced new test classes to validate properties of multi-system
objects regarding periodic boundary conditions.
	- Added a new test class for handling type mapping in labeled systems.

- **Bug Fixes**
- Updated existing test classes to improve clarity and consistency in
naming conventions for multi-system variables.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: Han Wang <[email protected]>

Author: wanghan-iapcm

tests/test_deepmd_mixed.py

@@ -117,6 +117,119 @@ def test_str(self):
         )
 
 
+class TestMixedMultiSystemsDumpLoadTypeMap(
+    unittest.TestCase, CompLabeledMultiSys, MultiSystems, MSAllIsNoPBC
+):
+    def setUp(self):
+        self.places = 6
+        self.e_places = 6
+        self.f_places = 6
+        self.v_places = 6
+
+        # C1H4
+        system_1 = dpdata.LabeledSystem(
+            "gaussian/methane.gaussianlog", fmt="gaussian/log"
+        )
+
+        # C1H3
+        system_2 = dpdata.LabeledSystem(
+            "gaussian/methane_sub.gaussianlog", fmt="gaussian/log"
+        )
+
+        tmp_data = system_1.data.copy()
+        tmp_data["atom_numbs"] = [1, 1, 1, 2]
+        tmp_data["atom_names"] = ["C", "H", "A", "B"]
+        tmp_data["atom_types"] = np.array([0, 1, 2, 3, 3])
+        # C1H1A1B2
+        system_1_modified_type_1 = dpdata.LabeledSystem(data=tmp_data)
+
+        tmp_data = system_1.data.copy()
+        tmp_data["atom_numbs"] = [1, 1, 2, 1]
+        tmp_data["atom_names"] = ["C", "H", "A", "B"]
+        tmp_data["atom_types"] = np.array([0, 1, 2, 2, 3])
+        # C1H1A2B1
+        system_1_modified_type_2 = dpdata.LabeledSystem(data=tmp_data)
+
+        tmp_data = system_1.data.copy()
+        tmp_data["atom_numbs"] = [1, 1, 1, 2]
+        tmp_data["atom_names"] = ["C", "H", "A", "D"]
+        tmp_data["atom_types"] = np.array([0, 1, 2, 3, 3])
+        # C1H1A1C2
+        system_1_modified_type_3 = dpdata.LabeledSystem(data=tmp_data)
+
+        self.ms = dpdata.MultiSystems(
+            system_1,
+            system_2,
+            system_1_modified_type_1,
+            system_1_modified_type_2,
+            system_1_modified_type_3,
+        )
+
+        self.ms.to_deepmd_npy_mixed("tmp.deepmd.mixed")
+        self.place_holder_ms = dpdata.MultiSystems()
+        self.place_holder_ms.from_deepmd_npy("tmp.deepmd.mixed", fmt="deepmd/npy")
+
+        new_type_map = ["H", "C", "D", "A", "B"]
+        self.systems = dpdata.MultiSystems()
+        self.systems.from_deepmd_npy_mixed(
+            "tmp.deepmd.mixed", fmt="deepmd/npy/mixed", type_map=new_type_map
+        )
+        for kk in [ii.formula for ii in self.ms]:
+            # apply type_map to each system
+            self.ms[kk].apply_type_map(new_type_map)
+            # revise keys in dict according because the type_map is updated.
+            tmp_ss = self.ms.systems.pop(kk)
+            self.ms.systems[tmp_ss.formula] = tmp_ss
+
+        self.ms_1 = self.ms
+        self.ms_2 = self.systems
+        mixed_sets = glob("tmp.deepmd.mixed/*/set.*")
+        self.assertEqual(len(mixed_sets), 2)
+        for i in mixed_sets:
+            self.assertEqual(
+                os.path.exists(os.path.join(i, "real_atom_types.npy")), True
+            )
+
+        self.system_names = [
+            "H4C1D0A0B0",
+            "H3C1D0A0B0",
+            "H1C1D0A1B2",
+            "H1C1D0A2B1",
+            "H1C1D2A1B0",
+        ]
+        self.system_sizes = {
+            "H4C1D0A0B0": 1,
+            "H3C1D0A0B0": 1,
+            "H1C1D0A1B2": 1,
+            "H1C1D0A2B1": 1,
+            "H1C1D2A1B0": 1,
+        }
+        self.atom_names = ["H", "C", "D", "A", "B"]
+
+    def tearDown(self):
+        if os.path.exists("tmp.deepmd.mixed"):
+            shutil.rmtree("tmp.deepmd.mixed")
+
+    def test_len(self):
+        self.assertEqual(len(self.ms), 5)
+        self.assertEqual(len(self.place_holder_ms), 2)
+        self.assertEqual(len(self.systems), 5)
+
+    def test_get_nframes(self):
+        self.assertEqual(self.ms.get_nframes(), 5)
+        self.assertEqual(self.place_holder_ms.get_nframes(), 5)
+        self.assertEqual(self.systems.get_nframes(), 5)
+
+    def test_str(self):
+        self.assertEqual(str(self.ms), "MultiSystems (5 systems containing 5 frames)")
+        self.assertEqual(
+            str(self.place_holder_ms), "MultiSystems (2 systems containing 5 frames)"
+        )
+        self.assertEqual(
+            str(self.systems), "MultiSystems (5 systems containing 5 frames)"
+        )
+
+
 class TestMixedMultiSystemsDumpLoadSetSize(
     unittest.TestCase, CompLabeledMultiSys, MultiSystems, MSAllIsNoPBC
 ):