Fix unit test for lstm_unit.

Author: pkuyym

python/paddle/v2/fluid/layers/nn.py

@@ -1199,9 +1199,12 @@ def lstm_unit(x_t,
     This layer has two outputs including :math:`h_t` and :math:`o_t`.
 
     Args:
-        x_t (Variable): The input value of current step, a 2-D tensor.
-        hidden_t_prev (Variable): The hidden value of lstm unit, a 2-D tensor.
-        cell_t_prev (Variable): The cell value of lstm unit, a 2-D tensor.
+        x_t (Variable): The input value of current step, a 2-D tensor with shape
+            M x N, M for batch size and N for input size.
+        hidden_t_prev (Variable): The hidden value of lstm unit, a 2-D tensor
+            with shape M x S, M for batch size and S for size of lstm unit.
+        cell_t_prev (Variable): The cell value of lstm unit, a 2-D tensor with
+            shape M x S, M for batch size and S for size of lstm unit.
         forget_bias (float): The forget bias of lstm unit.
         param_attr (ParamAttr): The attributes of parameter weights, used to set
             initializer, name etc.

python/paddle/v2/fluid/tests/test_layers.py

@@ -177,8 +177,8 @@ def test_lstm_unit(self):
                 name='x_t_data', shape=[10, 10], dtype='float32')
             x_t = layers.fc(input=x_t_data, size=10)
             prev_hidden_data = layers.data(
-                name='prev_hidden_data', shape=[10, 20], dtype='float32')
-            prev_hidden = layers.fc(input=prev_hidden_data, size=20)
+                name='prev_hidden_data', shape=[10, 30], dtype='float32')
+            prev_hidden = layers.fc(input=prev_hidden_data, size=30)
             prev_cell_data = layers.data(
                 name='prev_cell', shape=[10, 30], dtype='float32')
             prev_cell = layers.fc(input=prev_cell_data, size=30)