add example helpers

DESCRIPTION

@@ -26,14 +26,16 @@ Language: en
 Roxygen: list(markdown = TRUE)
 Imports:
     cli,
+    fs,
     pkgload,
     purrr,
-    rlang
+    rlang,
+    usethis
 Suggests: 
     rstudioapi,
     shinytest2,
-    testthat (>= 3.0.0)
+    testthat (>= 3.0.0),
+    withr
 Config/testthat/edition: 3
 Config/testthat/parallel: true
 Config/Needs/website: rmarkdown
-RoxygenNote: 7.3.2

NAMESPACE

@@ -5,3 +5,4 @@ export(path_ex_file)
 export(path_extdata)
 export(path_package_this)
 export(transform_with_generated)
+export(use_ex_file)

R/examples.R

@@ -15,6 +15,34 @@ source_pef <- function(...) {
   source(path_ex_file(...), local = TRUE)$value
 }
 
+#' Create or edit example files
+#'
+#' This function creates R files in the `inst/examples/` to be reused in
+#' tests, `#' @examples` and more.
+#' When reused for tests, only last return of an example file will be tested.
+#' You may therefore need a lot of relatively small example files.
+#' The suggested convention is to sort them in folders named by `file_name`
+#' function name and test name.
+#'
+#' @inheritParams fs::path
+#' @inheritParams usethis::use_template
+#' @export
+#' @keywords example helpers
+use_ex_file <- function(..., open = rlang::is_interactive()) {
+  # TODO https://github.com/dataheld/elf/issues/2
+  # take currently open file name from usethis
+  usethis::use_directory(example_path)
+  path <- fs::path(example_path, ..., ext = "R")
+  usethis::use_template(
+    "example.R",
+    save_as = path,
+    open = open,
+    package = "elf"
+  )
+}
+
+example_path <- fs::path("inst", "examples")
+
 #' Create path to example files
 #' Used in example tag and tests
 #' @inheritParams path_package_this

inst/templates/example.R

@@ -0,0 +1 @@
+# only last return can be tested