Pega 8 is pretty strong in supporting automated testing. It has some inbuilt features that are very useful for supporting your automated regression test. For instance, PegaUnit is very useful for your unit tests, but it can also be used to check the connectivity to external parties (create a seperate suite which runs unit tests on the data pages/activities that use the connections).
You can also use the OOTB API to support your higher level tests (e.g. create/update/retrieve cases, assignments and data).
For UI testing, Pega has released scenario testing (make sure you open a case portal and click the gear on the bottom right to reveal the automation recorder). However, at this time we do not use it for automated UI-regression tests. It is pretty suitable for smoke tests, but when you want a maintainable, robust UI testsuite, I would recommend a non-Pega tool for now.