Continuous Integration involves frequent automated builds (including automated tests) to detect integration errors as quickly as possible in a team development setting.
Fantastic hosted code-coverage testing and reporting. Free for public open source projects on Github or Bitbucket, if you're writing in one of their supported languages (Python, Ruby, NodeJS, PHP) (using Travis or Codeship or CircleCI or Semaphore or Drone)
TeamCity is a build management and continuous integration solution supporting both Java and .NET ... includes features such as "Pre-tested Commit" which prevents the check-in of code which fails tests cases.
It integrates tightly with most popular IDE's and version control systems