Need better handling of formulas

[dtkaplan]

When capturing a formula with check_blanks, what get's captured is actually the call to generate the formula, not the formula itself. You need to evaluate the formula-call before you can compare it to another formula, e.g.

check_blanks(code, quote(lm(..form.., data = iris)))
failif(eval(form) == (Sepal.Length ~ Species)

This seems awkward.