Fix inverse and add to tests

Author: elseml

bayesflow/adapters/transforms/nnpe.py

@@ -57,7 +57,7 @@ def forward(self, data: np.ndarray, stage: str = "inference", **kwargs) -> np.nd
         return data + noise
 
     def inverse(self, data: np.ndarray, **kwargs) -> np.ndarray:
-        return np.exp(data)
+        return data
 
     def get_config(self) -> dict:
         return serialize({"slab_scale": self.slab_scale, "spike_scale": self.spike_scale, "seed": self.seed})

tests/test_adapters/test_adapters.py

@@ -308,6 +308,7 @@ def test_nnpe(random_data):
     result_training = ad(random_data, stage="training")
     result_validation = ad(random_data, stage="validation")
     result_inference = ad(random_data, stage="inference")
+    result_inversed = ad(random_data, inverse=True)
     serialized = serialize(ad)
     deserialized = deserialize(serialized)
     reserialized = serialize(deserialized)
@@ -324,7 +325,8 @@ def test_nnpe(random_data):
             continue
         assert np.allclose(result_training[k], v)
 
-    # check that the validation and inference data is unchanged
+    # check that the validation and inference data as well as inversed results are unchanged
     for k, v in random_data.items():
         assert np.allclose(result_validation[k], v)
         assert np.allclose(result_inference[k], v)
+        assert np.allclose(result_inversed[k], v)