Fix issue with receiving 0-length strings & framed transport.

tests/test_framed_transport.py

@@ -37,6 +37,14 @@ def add(self, person):
         self.registry[person.name] = person
         return True
 
+    def get(self, name):
+        """
+        Person get(1: string name)
+        """
+        if name not in self.registry:
+            raise addressbook.PersonNotExistsError()
+        return self.registry[name]
+
 
 class FramedTransportTestCase(TestCase):
     def mk_server(self):
@@ -75,3 +83,10 @@ def test_able_to_communicate(self):
         assert success
         success = self.client.add(dennis)
         assert not success
+
+    def test_zero_length_string(self):
+        dennis = addressbook.Person(name='')
+        success = self.client.add(dennis)
+        assert success
+        success = self.client.get(name='')
+        assert success

thriftpy/transport/transport.py

@@ -156,6 +156,11 @@ def close(self):
         return self.__trans.close()
 
     def read(self, sz):
+        # Important: don't attempt to read the next frame if the caller
+        # doesn't actually need any data.
+        if sz == 0:
+            return b''
+
         ret = self.__rbuf.read(sz)
         if len(ret) != 0:
             return ret