Refactor file path and dataset validation

movement/io/save_poses.py

@@ -112,13 +112,7 @@ def to_dlc_df(
     to_dlc_file : Save the xarray dataset containing pose tracks directly
         to a DeepLabCut-style .h5 or .csv file.
     """
-    if not isinstance(ds, xr.Dataset):
-        raise log_error(
-            ValueError, f"Expected an xarray Dataset, but got {type(ds)}."
-        )
-
-    ds.poses.validate()  # validate the dataset
-
+    _validate_dataset(ds)
     scorer = ["movement"]
     bodyparts = ds.coords["keypoints"].data.tolist()
     coords = ds.coords["space"].data.tolist() + ["likelihood"]
@@ -197,15 +191,7 @@ def to_dlc_file(
     >>> save_poses.to_dlc_file(ds, "/path/to/file_dlc.h5")
     """
 
-    try:
-        file = ValidFile(
-            file_path,
-            expected_permission="w",
-            expected_suffix=[".csv", ".h5"],
-        )
-    except (OSError, ValueError) as error:
-        logger.error(error)
-        raise error
+    file = _validate_file_path(file_path, expected_suffix=[".csv", ".h5"])
 
     # Sets default behaviour for the function
     if split_individuals == "auto":
@@ -236,3 +222,61 @@ def to_dlc_file(
         if isinstance(df_all, pd.DataFrame):
             _save_dlc_df(file.path, df_all)
         logger.info(f"Saved PoseTracks dataset to {file.path}.")
+
+
+def _validate_file_path(
+    file_path: Union[str, Path], expected_suffix: list[str]
+) -> ValidFile:
+    """Validate the input file path by checking that the file has
+    write permission and expected suffix(es). If the file is not valid,
+    an appropriate error is raised.
+
+    Parameters
+    ----------
+    file_path : pathlib.Path or str
+        Path to the file to validate.
+    expected_suffix : list of str
+        Expected suffix(es) for the file.
+
+    Returns
+    -------
+    ValidFile
+        The validated file.
+
+    Raises
+    ------
+    OSError
+        If the file cannot be written.
+    ValueError
+        If the file does not have the expected suffix.
+    """
+    try:
+        file = ValidFile(
+            file_path,
+            expected_permission="w",
+            expected_suffix=expected_suffix,
+        )
+    except (OSError, ValueError) as error:
+        logger.error(error)
+        raise error
+    return file
+
+
+def _validate_dataset(ds: xr.Dataset) -> None:
+    """Validate the input dataset is an xarray Dataset with valid PoseTracks.
+
+    Parameters
+    ----------
+    ds : xr.Dataset
+        Dataset to validate.
+
+    Raises
+    ------
+    ValueError
+        If `ds` is not an xarray Dataset with valid PoseTracks.
+    """
+    if not isinstance(ds, xr.Dataset):
+        raise log_error(
+            ValueError, f"Expected an xarray Dataset, but got {type(ds)}."
+        )
+    ds.poses.validate()  # validate the dataset