Is calling test_path() at a global level within a helper-*.R file not supported?

[DavisVaughan]

In the censored package we had a helper- file that loaded some helper data objects with test_path() and readRDS(). Like this:
https://github.com/tidymodels/censored/pull/145/files#diff-86973057dbc44244492fcd424b56710d5bccdab7c751ca7d469b4c744f85606aL1

It turns out that this doesn't work. You can easily reproduce with this repo:
https://github.com/DavisVaughan/testthathelperpath

Just do load_all(), which errors with:

> devtools::load_all(".")
ℹ Loading testthathelperpath
Error in `test_path()`:
! Can't find `tests/testthat/` in current directory.
Run `rlang::last_error()` to see where the error occurred.

> rlang::last_trace()
<error/rlang_error>
Error in `test_path()`:
! Can't find `tests/testthat/` in current directory.
Backtrace:
     ▆
  1. └─devtools::load_all(".")
  2.   └─pkgload::load_all(...)
  3.     ├─withr withr_with_envvar(...)
  4.     │ └─base::force(code)
  5.     └─testthat testthat_source_test_helpers(find_test_dir(path), env = pkg_env(package))
  6.       └─testthat::source_dir(path, "^helper.*\\.[rR]$", env = env, wrap = FALSE)
  7.         └─base::lapply(files, source_file, env = env, chdir = chdir, wrap = wrap)
  8.           └─testthat FUN(X[[i]], ...)
  9.             └─base::eval(exprs, env)
 10.               └─base::eval(exprs, env)
 11.                 ├─base::readRDS(test_path("data", "data.rds")) at tests/testthat/helper-load.R:2:0
 12.                 └─testthat::test_path("data", "data.rds")
 13.                   └─rlang::abort("Can't find `tests/testthat/` in current directory.")

There are lots of ways to work around this, but I was a bit surprised that this didn't work so we figured it was best to open an issue

[gaborcsardi]

That might not work, depending which test function you use. E.g. devtools::test() sources the helper files before calling testthat, so testthat couldn't have had time to set up the package, paths, etc. yet.

[DavisVaughan]

Do you think it is a bug? Maybe a devtools bug? If not, I am happy to close this since we have workarounds

[gaborcsardi]

I don't think a bug, it is a consequence of how devtools + testthat work together. It would also be rather inconvenient to consider it a bug, because I am not sure if there is a way to fix it.

[DavisVaughan]

That is what I figured, good enough for me!

[DanChaltiel]

@gaborcsardi I encounter this too.
If you really want to consider it not a bug, could we say that this is at least an unexpected behavior?
I think it would be worth documenting in ?test_path where it works and where it does not.

[gaborcsardi]

Its manual says:

This function is designed to work both interactively and during
tests, locating files in the ‘tests/testthat’ directory

I guess we could say that it works in test files, but not in helper files. Do you want to submit a PR?