[test] fix bug in blobs fs backend benchmark test

The new benchmark test for blobs fs backend was rebased from a merge
request in which it was written using the new interface for blobs
backend. After rebase, the test was not reverted to old interface, and
was just failing bad. This commit fixes it.

tests/benchmarks/test_blobs_fs_backend.py

@@ -2,6 +2,7 @@ import pytest
 from io import BytesIO
 from leap.soledad.server._blobs import FilesystemBlobsBackend
 from twisted.internet import defer
+from twisted.web.test.test_web import DummyRequest
 
 
 def create_write_test(amount, size):
@@ -14,7 +15,9 @@ def create_write_test(amount, size):
         deferreds = []
         for i in xrange(amount):
             fd = BytesIO(data)
-            d = backend.write_blob('user', str(i), fd)
+            request = DummyRequest([''])
+            request.content = fd
+            d = backend.write_blob('user', str(i), request)
             deferreds.append(d)
         yield txbenchmark(defer.gatherResults, deferreds)
 
@@ -39,16 +42,19 @@ def create_read_test(amount, size):
         deferreds = []
         for i in xrange(amount):
             fd = BytesIO(data)
-            d = backend.write_blob('user', str(i), fd)
+            request = DummyRequest([''])
+            request.content = fd
+            d = backend.write_blob('user', str(i), request)
             deferreds.append(d)
         yield defer.gatherResults(deferreds)
 
         # ... then measure the read operation
         deferreds = []
         for i in xrange(amount):
-            d = backend.read_blob('user', str(i))
-            d.addCallback(lambda fd: fd.read())
+            request = DummyRequest([''])
+            d = request.notifyFinish()
             deferreds.append(d)
+            backend.read_blob('user', str(i), request)
         yield txbenchmark(defer.gatherResults, deferreds)
 
     return test