The test runs quickly. There is no dependence upon actual database and network connections.
测试可以快速运行，不需要依赖真实的数据库，也不需要网络连接。
2
It can introduce order dependence into the test suite and hide bugs.
它有可能在测试套件中引入顺序依赖，并隐藏bug。
3
Because of their dependence on coded test cases, cryptic interfaces, and the variety of tools necessary to test in different environments, the use of these tools is often limited to developers.