@marcoleary has mentioned that there are several dependencies that could be easily removed from this project. While we're at it we might as well update the versions of all other dependencies. Once this has been done I'll enable Dependabot for this repository.
PHPUnit 8 deprecated @expectedException, @expectedExceptionCode, @expectedExceptionMessage, and @expectedExceptionMessageRegExp. They will be removed in PHPUnit 9.
expectException(), expectExceptionCode(), expectExceptionMessage(), or expectExceptionMessageRegExp() should be used respectively.
PHP is about to remove support for security fixes to PHP 7.1 and move to security fixes for 7.2 and above. We could also do with adding type hints etc. but I'm happy for that to be done in a separate pull request due to broad range of changes that will result in.
While do currently have a test suite for this project, it would be great to add more tools to improve the standard of the library. We can then integrate these with our work in #14.