Finally, it is possible to enforce one or more policies on pull requests to a specific branch. The interface for branch policies is shown in the following screenshot and can be accessed by choosing the Branch policies option while managing the authorizations on a repository branch:

The first four checkboxes are related to default policies that can be enabled (or not) on your preference. By default, they are all disabled.

Build validation can be used to disallow the merge of any pull request if one or more of the select builds have not completed successfully. How to set up such a build is something you will learn in the next chapter.

Next to builds, you can also call external services to inspect the pull request and to allow or disallow it. An often used integration here is with a code quality tool. You might also call your own APIs here, to enforce team agreements on things such as pull request titles, relation to work items, or more complex constraints.

Finally, you can enforce that a specific user or group has to be included in the review of a pull request. This might be needed to enforce a specific level of quality, but it can also be a limiting factor on your development speed and hence flow.