test: use function factory instead of {mockery}

[maelle]

Reference: https://adv-r.hadley.nz/function-factories.html#factory-fundamentals

mock_factory <- function(...) {
  i <- 0
  
  function(...) {
    things <- c("3", "This is a note", "n")
    i <<- i + 1
    things[i]
  }
}

new_mock <- mock_factory()
new_mock()
#> [1] "3"
new_mock()
#> [1] "This is a note"
new_mock()
#> [1] "n"
new_mock()
#> [1] NA

^{Created on 2025-02-19 with reprex v2.1.1}

[maelle]

I must say I still have trouble wrapping my head around function factories 🤯

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

[maelle]

the ellipsis is actually probably not needed here 🤔

[maelle]

@RayStick see also r-lib/testthat#1265 (comment) -- maybe you could define such a function in a helper file (tests/testthat/helper-mock.R), use it in your package, and if testthat ends up providing its own version of the function, you could replace your homemade function with that?

This way you could already drop mockery.

[RayStick]

@maelle thanks for your work on this! I am struggling to get my head around it at the moment

[RayStick]

Ah - think I got it! Working on it this morning

[maelle]

The PR to testthat is making progress, so hopefully in a little while you can use that function (and have mapmetadata depend on the dev version of testthat) r-lib/testthat#2061

[RayStick]

@maelle see my commit here: af5cd48
Shall we merge this in the time being, or best to wait? (if happy to merge, please remove draft PR status)
devtools::check() all pass :)

[maelle]

It's really nice especially with the explaining comments.

[RayStick]

Thanks @maelle

[RayStick]

@all-contributors add @maelle for code

[allcontributors]

@RayStick

I've put up a pull request to add @maelle! 🎉