Add test for PreprocessorPyTorch initialization

Signed-off-by: Nilaksh Das <[email protected]>

Author: nilakshdas

tests/defences/preprocessor/test_preprocessor.py

@@ -0,0 +1,33 @@
+import pytest
+
+from art.defences.preprocessor.preprocessor import PreprocessorPyTorch
+from tests.utils import ARTTestException
+
+
+class DummyPreprocessorPyTorch(PreprocessorPyTorch):
+    def forward(self, x, y):
+        return x, y
+
+
+@pytest.mark.parametrize("is_fitted", [True, False])
+@pytest.mark.parametrize("apply_fit", [True, False])
+@pytest.mark.parametrize("apply_predict", [True, False])
+@pytest.mark.only_with_platform("pytorch")
+def test_preprocessor_pytorch_init(art_warning, is_fitted, apply_fit, apply_predict):
+    try:
+        import torch
+
+        preprocessor = DummyPreprocessorPyTorch(
+            device_type="cpu",
+            is_fitted=is_fitted,
+            apply_fit=apply_fit,
+            apply_predict=apply_predict,
+        )
+
+        assert preprocessor.device == torch.device("cpu")
+        assert preprocessor.is_fitted == is_fitted
+        assert preprocessor.apply_fit == apply_fit
+        assert preprocessor.apply_predict == apply_predict
+
+    except ARTTestException as e:
+        art_warning(e)