[niothiel]

Per your typo point, this has already been solved by linting. If I made a typo like that, any decent editor (Sublime in my case) would draw a big red box and complain at me for using an undeclared variable. In the case of a typo on assignment as in your example, the linter would report a variable declaration without usages.

Per your testing point, so what? Doesn't everyone strive for 100% code coverage anyway? One of the big advantages of dynamic languages is that more functionality can be implemented in less code which in turn makes it easier to hit that 100% coverage.

[blub]

Good point, one just has to every now and then open all files in Sublime and check for red squiggles :)

And not everyone is striving for 100% code coverage unless it really matters (e.g. SQLite). A beneficial activity becomes harmful if taken to extremes.