Is it possible to determine test order in testthat?

I am using testthat to check the code in my package. Some of my tests are for basic functionality, such as constructors and getters. Others are for complex functionality that builds on top of the basic functionality. If the basic tests fail, then it is expected that the complex tests will fail, so there is no point testing further.

Is it possible to:

1. Ensure that the basic tests are always done first
2. Make a test-failure halt the testing process