git2r should not be a dependency for user side, e.g. when using use_precommit()

Author: lorenzwalthert

NEWS.md

@@ -9,6 +9,7 @@ editor_options:
 -   Ensure sorting for `spell-check` hook is case-insensitive on all
     operating systems. This may re-order your whole `inst/WORDLIST`
     (#405).
+-   {git2r} is no longer needed for user side (#417).
 -   Fix bug that prevented pkg load outside directories with precommit
     files (@mpadge, #413).
 -   hook `forbid-to-commit` in template `.pre-commit-config.yaml` has

R/assert.R

@@ -1,5 +1,5 @@
 assert_is_git_repo <- function(root) {
-  if (is.null(git2r::discover_repository(root))) {
+  if (!is_git_repo(root = root)) {
     rlang::abort(paste0(
       "The directory ", root, " is not a git repo. Please navigate to ",
       root, " and init git in ",

R/utils.R

@@ -108,3 +108,21 @@ rev_as_pkg_version <- function(rev) {
 has_git <- function() {
   nzchar(Sys.which("git"))
 }
+
+is_git_repo <- function(root = here::here()) {
+  withr::local_dir(root)
+  if (has_git()) {
+    rlang::with_handlers(
+      {
+        output <- call_and_capture(
+          "git",
+          c("rev-parse", "--is-inside-work-tree")
+        )
+        output$exit_status == 0 && as.logical(toupper(output$stdout))
+      },
+      erorr = function(...) FALSE
+    )
+  } else {
+    dir.exists(".git")
+  }
+}

man/git_init.Rd

@@ -16,6 +16,13 @@ test_that("call capturing for pass", {
   )
 })
 
+test_that("git repo status can be evaluated", {
+  tmpdir <- local_test_setup(git = FALSE)
+  expect_false(is_git_repo(root = tmpdir))
+  git_init(tmpdir)
+  expect_true(is_git_repo(root = tmpdir))
+})
+
 test_that("call capturing for error (command that does not exist)", {
   expect_silent(captured <- call_and_capture("j23lkjsdi", "1"))
   expect_true(