add test

Author: xuyuting

obsidian/parameters/transforms.py

@@ -86,6 +86,7 @@ def forward(self,
             self._validate_fit()
         if self.params["sd"] == 0:
             # In the edge case where `X` is degenerate, avoid 0 divided by 0
+            warnings.warn('Transform constant target values by mean subtraction', UserWarning)
             return zeros_like(X)
         else:
             return (X-self.params['mu'])/self.params['sd']

obsidian/tests/test_parameters.py

@@ -255,7 +255,16 @@ def test_target_validation():
     with pytest.warns(UserWarning):
         transform_func = Logit_Scaler(range_response=100)
         transform_func.forward(test_neg_response, fit=False)
-        
-        
+
+    # Transform constant target values
+    test_constant_response = torch.zeros(10) + 9.0
+    with pytest.warns(UserWarning):
+        Target('Response1', f_transform='Standard').transform_f(test_constant_response, fit=True)
+
+    # Corner case for Logit_Scaler
+    transform_func = Logit_Scaler(standardize=False)
+    transform_func.forward(test_response, fit=True)
+
+
 if __name__ == '__main__':
     pytest.main([__file__, '-m', 'fast'])