fix: 🐛 abort use_targets_template() if file name is not _targets.R (#181)

# Description

And update tests for match this.

Needs no review. 

## Checklist

- [X] Ran `just run-all`

Author: signekb

R/use-targets.R

@@ -13,7 +13,9 @@ use_targets_template <- function(
   path = "_targets.R",
   open = rlang::is_interactive()
 ) {
-  checkmate::assert_string(fs::path_file(path), "_targets.R")
+  if (fs::path_file(path) != "_targets.R") {
+    cli::cli_abort("File name must be {.file _targets.R}.")
+  }
 
   template_path <- fs::path_package("fastreg", "template-targets.R")
 

tests/testthat/test-targets.R

@@ -19,16 +19,17 @@ test_that("created file matches template content", {
   )
 })
 
-test_that("returns path invisibly", {
-  temp_path <- fs::path_temp("test_return.R")
-  result <- use_targets_template(temp_path, open = FALSE)
-  expect_equal(result, temp_path)
-})
-
 test_that("template is valid R code", {
   expect_no_error(parse(file = template_path))
 })
 
+test_that("use_targets_template() errors with incorrect `path`", {
+  expect_error(
+    use_targets_template(fs::path_temp("not-targets.R")),
+    regexp = "_targets.R"
+  )
+})
+
 # Test pipeline ----------------------------------------------------------------
 
 test_that("targets pipeline template converts SAS files to Parquet", {