Check if mask_dir is available for segmentation task in Folder da…

…ta (openvinotoolkit#1277)

* Fix metadata path

* Ignore hidden directories in folder dataset

* Add check for mask_dir for segmentation tasks in Folder dataset

* Check the test split mode when no mask dir is provided

src/anomalib/data/folder.py

@@ -281,8 +281,13 @@ def __init__(
  seed=seed,
  )
 
- self.normal_split_ratio = normal_split_ratio
+ if task == TaskType.SEGMENTATION and test_split_mode == TestSplitMode.FROM_DIR and mask_dir is None:
+ raise ValueError(
+ f"Segmentation task requires mask directory if test_split_mode is {test_split_mode}. "
+ f"You could set test_split_mode to {TestSplitMode.NONE} or provide a mask directory."
+ )
 
+ self.normal_split_ratio = normal_split_ratio
  transform_train = get_transforms(
  config=transform_config_train,
  image_size=image_size,