diff --git a/tests/core/collators/test_utils.py b/tests/core/collators/test_pakcer_unpacker.py
similarity index 62%
rename from tests/core/collators/test_utils.py
rename to tests/core/collators/test_pakcer_unpacker.py
index 74c54a36..8e5b5e09 100644
--- a/tests/core/collators/test_utils.py
+++ b/tests/core/collators/test_pakcer_unpacker.py
@@ -1,36 +1,36 @@
 
-from fastNLP.core.collators.utils import *
+from fastNLP.core.collators.packer_unpacker import *
 
 
 def test_unpack_batch_mapping():
     batch = [{'a': [1, 2], 'b': 1}, {'a': [3], 'b': 2}]
-    assert unpack_batch_mapping(batch, {})=={'a': [[1, 2], [3]], 'b': [1, 2]}
+    assert MappingPackerUnpacker.unpack_batch(batch, {}, {})=={'a': [[1, 2], [3]], 'b': [1, 2]}
 
 
 def test_unpack_batch_nested_mapping():
     batch = [{'a': [1, 2], 'b': 1, 'c': {'c': 1}}, {'a': [3], 'b': 2, 'c': {'c': 2}}]
-    assert unpack_batch_nested_mapping(batch, {}, {}) == {'a': [[1, 2], [3]], 'b': [1, 2], ('c','c'): [1, 2]}
+    assert NestedMappingPackerUnpacker.unpack_batch(batch, {}, {}) == {'a': [[1, 2], [3]], 'b': [1, 2], ('c','c'): [1, 2]}
 
     batch = [{'a': [1, 2], 'b': 1, 'c': {'c': {'c': 1}}}, {'a': [3], 'b': 2, 'c': {'c': {'c': 2}}}]
-    assert unpack_batch_nested_mapping(batch, {}, {}) == {'a': [[1, 2], [3]], 'b': [1, 2], ('c', 'c', 'c'): [1, 2]}
+    assert NestedMappingPackerUnpacker.unpack_batch(batch, {}, {}) == {'a': [[1, 2], [3]], 'b': [1, 2], ('c', 'c', 'c'): [1, 2]}
 
     batch = [{'a': [1, 2], 'b': 1, 'c': {'c': {'c': 1, 'd':[1, 1]}, 'd': [1]}},
              {'a': [3], 'b': 2, 'c': {'c': {'c': 2, 'd': [2, 2]}, 'd': [2, 2]}}]
-    assert unpack_batch_nested_mapping(batch, {}, {}) == {'a': [[1, 2], [3]], 'b': [1, 2], ('c', 'c', 'c'): [1, 2],
+    assert NestedMappingPackerUnpacker.unpack_batch(batch, {}, {}) == {'a': [[1, 2], [3]], 'b': [1, 2], ('c', 'c', 'c'): [1, 2],
                                                           ('c','c', 'd'):[[1, 1], [2, 2]], ('c', 'd'): [[1], [2, 2]]}
 
 
 def test_pack_batch_nested_mapping():
     batch = {'a': [[1, 2], [3]], 'b': [1, 2], ('c', 'c', 'c'): [1, 2],
              ('c', 'c', 'd'):[[1, 1], [2, 2]], ('c', 'd'): [[1], [2, 2]]}
-    new_batch = pack_batch_nested_mapping(batch)
+    new_batch = NestedMappingPackerUnpacker.pack_batch(batch)
     assert new_batch == {'a': [[1, 2], [3]], 'b': [1, 2],
                          'c': {'c':{'c': [1, 2], 'd': [[1, 1], [2, 2]]}, 'd':[[1], [2, 2]]}}
 
 
 def test_unpack_batch_sequence():
     batch = [[1, 2, 3], [2, 4, 6]]
-    new_batch = unpack_batch_sequence(batch, {})
+    new_batch = SequencePackerUnpacker.unpack_batch(batch, {}, {})
     assert new_batch == {'_0': [1, 2], '_1': [2, 4], '_2': [3, 6]}