refactor: use checkmate for arg validation

[dshemetov]

Related to https://github.com/cmu-delphi/epiprocess/issues/403.

I took the safe approach of changing the internals of the arg functions to use checkmate, that way we can rely on the existing unit tests and don't need to change any other epipredict code. The functions look a lot simpler and more unified now. We could eventually get rid of these wrappers and just invoke check functions directly, but that would take more refactoring work.

[dshemetov]

Good question right, I brought back the handle_arg_list since it handled grabbing names well. Checkmate does quite well with preserving variable names in errors.

r$> r1 <- epi_recipe(x) %>%
          step_epi_ahead(death_rate, ahead = 3.6) %>%
          step_epi_lag(death_rate, lag = 1.9)
Error in (function (name, value)  : 
  Assertion on 'ahead' failed: Must be of type 'integerish', but element 1 is not close to an integer.

r$> r2 <- epi_recipe(x) %>%
          step_epi_ahead(death_rate, ahead = 7) %>%
          step_epi_lag(death_rate, lag = -7)
Error in (function (name, value)  : 
  Assertion on 'lag' failed: Element 1 is not >= 0.

r$> step_growth_rate(r, value, role = 1)
Error in (function (name, value)  : 
  Assertion on 'role' failed: Must be of type 'character', not 'double'.

r$> step_growth_rate(r, value, horizon = 0)
Error in (function (name, value)  : 
  Assertion on 'horizon' failed: Element 1 is not >= 1.

[dshemetov]

FWIW, traceback() can lead the user there

r$> r1 <- epi_recipe(x) %>%
              step_epi_ahead(death_rate, ahead = 3.6) %>%
              step_epi_lag(death_rate, lag = 1.9)
Error in (function (name, value)  : 
  Assertion on 'ahead' failed: Must be of type 'integerish', but element 1 is not close to an integer.

r$> traceback()
15: stop(simpleError(sprintf(msg, ...), call.))
14: mstop("Assertion on '%s' failed: %s.", var.name, res, call. = sys.call(-2L))
13: makeAssertion(x, res, .var.name, add)
12: assert_integerish(value, null.ok = allow_null, lower = 0, any.missing = FALSE, 
        .var.name = name) at utils-arg.R#63
11: (function (name, value) 
    {
        assert_integerish(value, null.ok = allow_null, lower = 0, 
            any.missing = FALSE, .var.name = name)
    })(dots[[1L]][[1L]], dots[[2L]][[1L]])
10: mapply(.f, .x, .y, MoreArgs = list(...), SIMPLIFY = FALSE) at compat-purrr.R#72
9: map2(.x, .y, .f, ...) at compat-purrr.R#15
8: walk2(names, values, .tests) at utils-arg.R#10
7: handle_arg_list(..., .tests = function(name, value) {
       assert_integerish(value, null.ok = allow_null, lower = 0, 
           any.missing = FALSE, .var.name = name)
   }) at utils-arg.R#62
6: arg_is_nonneg_int(ahead) at step_epi_shift.R#126
5: step_epi_ahead(., death_rate, ahead = 3.6)
4: inherits(x, "epi_recipe") at epi_recipe.R#221
3: is_epi_recipe(recipe) at step_epi_shift.R#64
2: step_epi_lag(., death_rate, lag = 1.9)
1: epi_recipe(x) %>% step_epi_ahead(death_rate, ahead = 3.6) %>% 
       step_epi_lag(death_rate, lag = 1.9)

[dajmcdon]

True, though it would be nice if Error in (function (name, value) : said Error in step_epi_ahead() : instead.