complete roxygen for is_treesitter_installed() and a manual test file

R/namespaced_function_calls.R

@@ -37,7 +37,7 @@
 #'
 #' @export
 namespaced_function_calls <- function(allow = NULL) {
-  if (is_treesitter_installed()) {
+  if (!is_treesitter_installed()) {
     cli::cli_alert_warning(
       paste(
         "The packages {{treesitter}} and {{treesitter.r}} are required by",

R/style_box_use.R

@@ -526,7 +526,7 @@ rebuild_source_file <- function(source_file_lines, retain_lines, transformed_box
 
 #' @keywords internal
 check_treesitter_installed <- function() {
-  if (is_treesitter_installed()) {
+  if (!is_treesitter_installed()) {
     cli::cli_abort(
       paste(
         "The packages {{treesitter}} and {{treesitter.r}} are required for styling.",
@@ -540,8 +540,23 @@ check_treesitter_installed <- function() {
 #'
 #' Treesitter required R >= 4.3.0. Treesitter is required by a few `{box.linters}` functions.
 #'
+#'
+#' @examples
+#' \dontrun{
+#'
+#' # Bare environment
+#'
+#' is_treesitter_installed()
+#' #> [1] FALSE
+#'
+#' install.packages(c("treesitter", "treesitter.r"))
+#' is_treesitter_installed()
+#' #> [1] TRUE
+#' }
+#'
+#' @return Logical TRUE/FALSE if the `treesitter` dependencies exist.
 #' @export
 is_treesitter_installed <- function() {
   treesitter_pkgs <- c("treesitter", "treesitter.r")
-  length(find.package(treesitter_pkgs, quiet = TRUE)) < length(treesitter_pkgs)
+  length(find.package(treesitter_pkgs, quiet = TRUE)) >= length(treesitter_pkgs)
 }

tests/e2e/test-is_treesitter_installed.R

@@ -0,0 +1,44 @@
+# How to test is_treesitter_installed()
+#
+# `withr` provides a function to temporarily install packages `withr::with_package()` in an
+# environment. There is, however, no currently existing way to temporarily uninstalled packages
+# to test environments without certain packages.
+#
+# To test `is_treesitter_installed()`, a manual test has to be executed.
+
+devtools::load_all()
+
+remove.packages(c("treesitter", "treesitter.r"))
+
+testthat::test_that("is_treesitter_installed() returns FALSE when none is installed", {
+  result <- is_treesitter_installed()
+
+  testthat::expect_false(result)
+})
+
+testthat::test_that("is_treesitter_installed() returns FALSE when only treesitter is installed", {
+  install.packages("treesitter")
+
+  result <- is_treesitter_installed()
+
+  testthat::expect_false(result)
+  remove.packages("treesitter")
+})
+
+testthat::test_that("is_treesitter_installed() returns FALSE when only treesitter.r is installed", {
+  install.packages("treesitter.r")
+
+  result <- is_treesitter_installed()
+
+  testthat::expect_false(result)
+  remove.packages("treesitter.r")
+})
+
+install.packages(c("treesitter", "treesitter.r"))
+
+testthat::test_that("is_treesitter_installed() returns TRUE", {
+  result <- is_treesitter_installed()
+
+  testthat::expect_true(result)
+})
+