If you want to run tests for an app, you have to enable the Run tests after build option in the build configuration of the app. All tests defined in the source code will then be run automatically after the build job has finished. You can also enable the Require tests to pass option to define that a build job can only receive the build status "Success" if all tests have run successfully. See also Adding a Build Configuration.

In the details of the resulting build job, you can then see how many tests have been run and whether they were successful or not.