refactor(tests): replace lambdas with top-level functions

This change ensures that unit tests pass in Python 3.14, where the
forkserver start method is used by default and requires picklable
objects.

Author: adosar

tests/test_data.py

@@ -38,6 +38,9 @@
 from aidsorb.utils import pcd_from_dir
 
 
+def dummy_tfm(x):
+    return x - 1
+
 class TestPrepareData(unittest.TestCase):
     def setUp(self):
         self.tempdir = tempfile.TemporaryDirectory(dir='/tmp')
@@ -82,7 +85,7 @@ def setUp(self):
         self.index_col = 'id'
         self.labels = ['y1', 'y3']
         self.transform_x = Center()
-        self.transform_y = lambda y: y - 1
+        self.transform_y = dummy_tfm
         self.batch_size = 2
         self.channels_first = True
 

tests/test_datamodules.py

@@ -31,13 +31,17 @@
 from aidsorb.transforms import Center, RandomRotation
 
 
+def dummy_tfm(x):
+    return x - 1
+
+
 class TestPCDDataModule(unittest.TestCase):
     def setUp(self):
         # Arguments for the datamodule.
         self.train_size = 2
         self.train_trans_x = Center()
         self.eval_trans_x = RandomRotation()
-        self.trans_y = lambda y: y -1
+        self.trans_y = dummy_tfm
         self.shuffle = True
         self.drop_last = True
         self.train_bs = 3