[test][test_database] Code cleanup

beat/core/test/test_database.py

@@ -46,10 +46,10 @@ def test_export():
 
     name = "integers_db/1"
     obj = Database(prefix, name)
-    assert obj.valid, "\n  * %s" % "\n  * ".join(obj.errors)
+    nose.tools.assert_true(obj.valid, "\n  * %s" % "\n  * ".join(obj.errors))
 
     obj.export(tmp_prefix)
 
     # load from tmp_prefix and validates
     exported = Database(tmp_prefix, name)
-    assert exported.valid, "\n  * %s" % "\n  * ".join(exported.errors)
+    nose.tools.assert_true(exported.valid, "\n  * %s" % "\n  * ".join(exported.errors))