Subclass exceptions from standard library exceptions (#28)

dissect/squashfs/exceptions.py

@@ -2,17 +2,21 @@ class Error(Exception):
     pass
 
 
-class NotADirectoryError(Error):
+class FileNotFoundError(Error, FileNotFoundError):
     pass
 
 
-class NotAFileError(Error):
+class IsADirectoryError(Error, IsADirectoryError):
     pass
 
 
-class NotASymlinkError(Error):
+class NotADirectoryError(Error, NotADirectoryError):
     pass
 
 
-class FileNotFoundError(Error):
+class NotAFileError(Error):
+    pass
+
+
+class NotASymlinkError(Error):
     pass

tests/test_exceptions.py

@@ -0,0 +1,19 @@
+import pytest
+
+from dissect.squashfs import exceptions
+
+
+@pytest.mark.parametrize(
+    "exc, std",
+    [
+        (exceptions.FileNotFoundError, FileNotFoundError),
+        (exceptions.IsADirectoryError, IsADirectoryError),
+        (exceptions.NotADirectoryError, NotADirectoryError),
+    ],
+)
+def test_filesystem_error_subclass(exc: exceptions.Error, std: Exception) -> None:
+    assert issubclass(exc, std)
+    assert isinstance(exc(), std)
+
+    with pytest.raises(std):
+        raise exc()