PHP is not the best language to catch errors in code, like mistyped names of variables. This is what static code analysis tools (named linters or lints) can do: find bugs in code before it ever get executed. Linters don’t replace unit tests, but generally they are faster and cheaper to set up. I’ll talk about my XRef lint project (http://xref-lint.net/) as well as other helpful open source alternatives: phplint (http://www.icosaedro.it/phplint/), arcanist (http://phabricator.org/) and scrutinizer (https://scrutinizer-ci.com/).
Video producer: http://www.sfphp.org