Fix check for input size

Signed-off-by: Beat Buesser <[email protected]>

Author: Beat Buesser

art/attacks/evasion/shadow_attack.py

@@ -116,7 +116,8 @@ def generate(self, x: np.ndarray, y: Optional[np.ndarray] = None, **kwargs) -> n
         :param y: An array of a single target label.
         :return: An array with the adversarial examples.
         """
-        if x.shape[0] > 1 or y.shape[0]:
+        print(x.shape)
+        if x.shape[0] > 1 or y.shape[0] > 1:
             raise ValueError("This attack only accepts a single sample as input.")
 
         y = check_and_transform_label_format(y, self.estimator.nb_classes)