Perl 6 and Parrot Essentials, 2nd Edition

Writing Tests

As we mentioned earlier, contributions to the Parrot project are welcome. Contributing tests is a good place to start. You don’t have to understand the code behind a PASM opcode (or IMCC instruction) to test it, you only have to understand what it’s supposed to do. If you’re working on some code and it doesn’t do what the documentation advertises, you can isolate the problem in a test or series of tests and send them to the bug tracking system. There’s a good chance the problem will be fixed before the next release. Writing tests makes it a lot easier for the developer to know when they’ve solved your problem—it’s solved when your tests pass. It also prevents that problem from appearing again, because it’s checked every time anyone runs make test. As you move along, you’ll want to write tests for every bug you fix or new feature you add.

The Perl 5 testing framework is at the core of Parrot tests, particularly Test::Builder. Parrot’s Parrot::Test module is an interface to Test::Builder and implements the extra features needed for testing Parrot, like the fact that PASM code has to be compiled to bytecode before it runs.

The main Parrot tests are in the top-level t/ directory of the Parrot source tree. t/op contains tests for basic opcodes and t/pmc has tests for PMCs. The names of the test files indicate the functionality tested, like integer.t, number.t, and string.t. Part of the make test target is the command perl t/harness, which runs all the .t files in the subdirectories ...