add activation operator python test

paddle/operators/math/activation_functor.h

@@ -61,9 +61,9 @@ struct ExpGrad {
                   const framework::Tensor& X, const framework::Tensor& Y,
                   const framework::Tensor& dY, framework::Tensor* dX) {
     auto dx = framework::EigenVector<T>::Flatten(*dX);
-    auto dy = framework::EigenVector<T>::Flatten(dY);
+    auto y = framework::EigenVector<T>::Flatten(Y);
     auto* place = device_context.template get_eigen_device<Place>();
-    dx.device(*place) = dy.exp();
+    dx.device(*place) = y;
   }
 };
 

python/paddle/v2/framework/tests/test_relu_op.py

@@ -3,9 +3,9 @@ import numpy as np
 from op_test import OpTest
 
 
-class TestExp(OpTest):
+class TestRelu(OpTest):
     def setUp(self):
-        self.op_type = "exp"
+        self.op_type = "relu"
         self.inputs = {
             'X': np.random.uniform(-1, 1, [11, 17]).astype("float32")
         }