Fix file utilities and add basic tests

deepmd/tf/nvnmd/utils/fio.py

@@ -39,7 +39,7 @@ def is_file(self, file_name):
     def get_file_list(self, path) -> list:
         if self.is_file(path):
             return []
-        if self.is_path:
+        if self.is_path(path):
             listdir = os.listdir(path)
             file_lst = []
             for name in listdir:
@@ -53,8 +53,9 @@ def get_file_list(self, path) -> list:
 
 
 class FioDic:
-    r"""Input and output for dict class data
-    the file can be .json or .npy file containing a dictionary.
+    r"""Input and output for dictionary data.
+
+    The file can be a `.json` or `.npy` file containing a dictionary.
     """
 
     def __init__(self) -> None:
@@ -83,7 +84,7 @@ def get(self, jdata, key, default_value):
             return default_value
 
     def update(self, jdata, jdata_o):
-        r"""Update key-value pair is key in jdata_o.keys().
+        r"""Update key-value pairs if the key exists in ``jdata_o``.
 
         Parameters
         ----------
@@ -186,8 +187,10 @@ class FioTxt:
     def __init__(self) -> None:
         pass
 
-    def load(self, file_name="", default_value=[]):
-        r"""Load .txt file into string list."""
+    def load(self, file_name="", default_value=None):
+        r"""Load a text file into a list of strings."""
+        if default_value is None:
+            default_value = []
         if Fio().exits(file_name):
             log.info(f"load {file_name}")
             with open(file_name, encoding="utf-8") as fr:
@@ -198,11 +201,13 @@ def load(self, file_name="", default_value=[]):
             log.info(f"can not find {file_name}")
             return default_value
 
-    def save(self, file_name: str = "", data: list = []) -> None:
-        r"""Save string list into .txt file."""
+    def save(self, file_name: str = "", data: list | str | None = None) -> None:
+        r"""Save a list of strings into a text file."""
         log.info(f"write string to txt file {file_name}")
         Fio().create_file_path(file_name)
 
+        if data is None:
+            data = []
         if isinstance(data, str):
             data = [data]
         data = [d + "\n" for d in data]

doc/model/train-fitting-tensor.md

@@ -174,7 +174,7 @@ The loss section should be provided like
 In tensor mode, the identification of the label's type (global or atomic) is derived from the file name. The global label should be named `dipole.npy/raw` or `polarizability.npy/raw`, while the atomic label should be named `atomic_dipole.npy/raw` or `atomic_polarizability.npy/raw`. If wrongly named, DP will report an error
 
 ```bash
-ValueError: cannot reshape array of size xxx into shape (xx,xx). This error may occur when your label mismatch it's name, i.e. you might store global tensor in `atomic_tensor.npy` or atomic tensor in `tensor.npy`.
+ValueError: cannot reshape array of size xxx into shape (xx,xx). This error may occur when your label mismatches its name, i.e. you might store global tensor in `atomic_tensor.npy` or atomic tensor in `tensor.npy`.
 ```
 
 In this case, please check the file name of the label.

source/tests/tf/test_fio_utils.py

@@ -0,0 +1,31 @@
+# SPDX-License-Identifier: LGPL-3.0-or-later
+from deepmd.tf.nvnmd.utils.fio import (
+    Fio,
+    FioTxt,
+)
+
+
+def test_get_file_list(tmp_path):
+    """get_file_list should handle non-existent paths and collect files recursively."""
+    # create directory with one file
+    subdir = tmp_path / "sub"
+    subdir.mkdir()
+    file_path = subdir / "file.txt"
+    file_path.write_text("hello")
+
+    fio = Fio()
+
+    # existing directory returns the file
+    files = fio.get_file_list(str(tmp_path))
+    assert files == [str(file_path)]
+
+    # non-existent directory should return an empty list
+    missing = tmp_path / "missing"
+    assert fio.get_file_list(str(missing)) == []
+
+
+def test_fiotxt_load_default(tmp_path):
+    """FioTxt.load should return default empty list when file does not exist."""
+    fio_txt = FioTxt()
+    missing = tmp_path / "no.txt"
+    assert fio_txt.load(str(missing)) == []