refactor: ♻️ change use_targets_template() to use dir as input (#193)

# Description

Following this comment:
#181 (comment)

Closes #190 

Needs a quick review.

## Checklist

- [X] Ran `just run-all`

Author: signekb

R/use-targets.R

@@ -1,40 +1,40 @@
 #' Use a targets pipeline template for converting SAS registers to Parquet
 #'
-#' Copies a template to the given path.
+#' Copies a `_targets.R` template to the given directory.
 #'
-#' @param path Path to the file to create. Defaults to `_targets.R`.
+#' @param path Path to the directory where `_targets.R` will be created.
+#'   Defaults to the current directory.
 #' @param open Whether to open the file for editing.
 #'
-#' @returns The `path`, invisibly.
+#' @returns The path to the created file, invisibly.
 #'
 #' @export
 use_targets_template <- function(
-  path = "_targets.R",
+  path = ".",
   open = rlang::is_interactive()
 ) {
-  if (fs::path_file(path) != "_targets.R") {
-    cli::cli_abort("File name must be {.file _targets.R}.")
-  }
+  checkmate::assert_directory_exists(path)
+  target_file <- fs::path(path, "_targets.R")
 
   template_path <- fs::path_package("fastreg", "template-targets.R")
 
-  if (fs::file_exists(path)) {
+  if (fs::file_exists(target_file)) {
     cli::cli_abort(c(
-      "{.file {path}} already exists.",
-      "i" = "Delete it first or choose a different path."
+      "{.file {target_file}} already exists.",
+      "i" = "Delete it first or choose a different directory."
     ))
   }
 
-  fs::file_copy(path = template_path, new_path = path)
+  fs::file_copy(path = template_path, new_path = target_file)
 
-  if (fs::file_exists(path)) {
-    cli::cli_alert_success("Created {.file {path}}")
+  if (fs::file_exists(target_file)) {
+    cli::cli_alert_success("Created {.file {target_file}}")
     cli::cli_alert_info("Edit the {.code config} section to set your paths.")
   }
 
   if (open) {
-    utils::file.edit(path)
+    utils::file.edit(target_file)
   }
 
-  invisible(path)
+  invisible(target_file)
 }

man/use_targets_template.Rd

@@ -1,6 +1,6 @@
 # Setup ------------------------------------------------------------------------
-output_path <- fs::path_temp("_targets.R")
-use_targets_template(output_path, open = FALSE)
+output_path <- fs::path_temp()
+file_path <- use_targets_template(output_path, open = FALSE)
 template_path <- fs::path_package("fastreg", "template-targets.R")
 template_content <- readLines(template_path)
 
@@ -16,7 +16,7 @@ test_that("use_targets_template() errors when file already exists", {
 
 test_that("use_targets_template() creates file matching template content", {
   expect_equal(
-    readLines(output_path),
+    readLines(file_path),
     readLines(template_path)
   )
 })
@@ -25,10 +25,10 @@ test_that("use_targets_template() creates valid R code", {
   expect_no_error(parse(file = template_path))
 })
 
-test_that("use_targets_template() errors with incorrect `path`", {
+test_that("use_targets_template() errors with non-existing `path`", {
   expect_error(
-    use_targets_template(fs::path_temp("not-targets.R")),
-    regexp = "_targets.R"
+    use_targets_template(fs::path_temp("non-existing/dir")),
+    regexp = "does not exist"
   )
 })
 

tests/testthat/test-use-targets.R

@@ -192,7 +192,7 @@ but that can be adjusted in the pipeline to fit the available resources.
 pipeline_dir <- fs::path_temp("pipeline-dir")
 fs::dir_create(pipeline_dir)
 
-use_targets_template(path = fs::path(pipeline_dir, "_targets.R"))
+use_targets_template(path = pipeline_dir)
 ```
 
 ### Set input and output paths