add test code for testing variational rnn

test/modules/test_variational_rnn.py

@@ -0,0 +1,28 @@
+
+import torch
+import unittest
+
+from fastNLP.modules.encoder.variational_rnn import VarMaskedFastLSTM
+
+class TestMaskedRnn(unittest.TestCase):
+    def test_case_1(self):
+        masked_rnn = VarMaskedFastLSTM(input_size=1, hidden_size=1, bidirectional=True, batch_first=True)
+        x = torch.tensor([[[1.0], [2.0]]])
+        print(x.size())
+        y = masked_rnn(x)
+        mask = torch.tensor([[[1], [1]]])
+        y = masked_rnn(x, mask=mask)
+        mask = torch.tensor([[[1], [0]]])
+        y = masked_rnn(x, mask=mask)
+
+    def test_case_2(self):
+        masked_rnn = VarMaskedFastLSTM(input_size=1, hidden_size=1, bidirectional=False, batch_first=True)
+        x = torch.tensor([[[1.0], [2.0]]])
+        print(x.size())
+        y = masked_rnn(x)
+        mask = torch.tensor([[[1], [1]]])
+        y = masked_rnn(x, mask=mask)
+        xx = torch.tensor([[[1.0]]])
+        #y, hidden = masked_rnn.step(xx)
+        #step() still has a bug
+        #y, hidden = masked_rnn.step(xx, mask=mask)