add mongodb services in travis ci

AmosChenYQ · AmosChenYQ · commit 19b2a8c98fbe · 2021-06-06T14:35:51.000+08:00
diff --git a/.travis.yml b/.travis.yml
@@ -5,6 +5,8 @@ python:
 - '3.6'
 - '3.7'
 - '3.8'
+services:
+- mongodb
 install:
 - pip install -r requirements.txt
 - pip install coveralls
