Set up PHPUnit with WordPress: The WordPress tests are 3 – 4 years old; does it matter?

That seems to be an old repo, you should use Obviously trunk should be used if you want to use the tests with 4.6. Not sure how much difference there is in the infrastructure between the version (in other words, it is unlikely that you care how core does a specific test, therefor the staleness of the core tests might not be an issue at all)