Add suport for Mongo 3.4 (travis, fix tests)

mongoengine/mongodb_support.py

@@ -0,0 +1,21 @@
+"""
+Helper functions, constants, and types to aid with MongoDB v3.x support
+"""
+from mongoengine.connection import get_connection
+
+
+# Constant that can be used to compare the version retrieved with
+# get_mongodb_version()
+MONGODB_34 = (3, 4)
+MONGODB_32 = (3, 2)
+MONGODB_3 = (3, 0)
+MONGODB_26 = (2, 6)
+
+
+def get_mongodb_version():
+    """Return the version of the connected mongoDB (first 2 digits)
+
+    :return: tuple(int, int)
+    """
+    version_list = get_connection().server_info()['versionArray'][:2]     # e.g: (3, 2)
+    return tuple(version_list)