Quality assurance is an essential part of monitoring and controlling, so testing is certainly one activity. There should be unit testing by the developer (an opportunity to self-check their code) and integration, stress, and load testing as appropriate by the QA team.
But monitoring and controlling needs to look at all project risks and make decisions about how to address them. Project status meetings are a monitoring and controlling activity which can help keep a project on track. For example, one risk is that a task is severely underestimated. On a fixed price project, this can be a costly mistake which needs to be discovered during project execution and corrected as soon as possible. This might be through a re-negotiated project scope or application of additional resources.