fix: load_multiple crashed with empty input list (#32)

rul_datasets/reader/saving.py

@@ -68,8 +68,11 @@ def load_multiple(
         features: The feature arrays saved in `save_paths`
         targets: The target arrays saved in `save_paths`
     """
-    runs = [load(save_path, memmap) for save_path in save_paths]
-    features, targets = [list(x) for x in zip(*runs)]
+    if save_paths:
+        runs = [load(save_path, memmap) for save_path in save_paths]
+        features, targets = [list(x) for x in zip(*runs)]
+    else:
+        features, targets = [], []
 
     return features, targets
 

tests/reader/test_saving.py

@@ -1,5 +1,6 @@
 import os.path
 from pathlib import Path
+from unittest import mock
 
 import numpy as np
 import numpy.testing as npt
@@ -36,6 +37,16 @@ def test_load(tmp_path, file_name):
     npt.assert_equal(loaded_targets, targets)
 
 
+@mock.patch("rul_datasets.reader.saving.load", return_value=(None, None))
+@pytest.mark.parametrize("file_names", [["run1", "run2"], []])
+def test_load_multiple(mock_load, file_names):
+    features, targets = saving.load_multiple(file_names)
+
+    mock_load.assert_has_calls([mock.call(name, False) for name in file_names])
+    assert len(features) == len(file_names)
+    assert len(targets) == len(file_names)
+
+
 @pytest.mark.parametrize("file_name", ["run", "run.npy"])
 def test_exists(tmp_path, file_name):
     save_path = os.path.join(tmp_path, file_name)