unittests: Add tests for tv_list_find*() functions

Additional modifications:

- More `const` qualifiers in tested functions.
- `tv_list_find_str()` second argument is more in-line with other
  `tv_list_find*()` functions.

1 files changed, 6 insertions, 6 deletions

diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index b0b95e955f..ef64467ee5 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -731,7 +731,7 @@ listitem_T *tv_list_find(list_T *const l, int n)
 ///                         `*ret_error` is not touched.
 ///
 /// @return Integer value at the given index or -1.
-varnumber_T tv_list_find_nr(list_T *const l, const int n, bool *ret_error)
+varnumber_T tv_list_find_nr(list_T *const l, const int n, bool *const ret_error)
   FUNC_ATTR_WARN_UNUSED_RESULT
 {
   const listitem_T *const li = tv_list_find(l, n);
@@ -744,16 +744,16 @@ varnumber_T tv_list_find_nr(list_T *const l, const int n, bool *ret_error)
   return tv_get_number_chk(&li->li_tv, ret_error);
 }
 
-/// Get list item l[n - 1] as a string
+/// Get list item l[n] as a string
 ///
 /// @param[in]  l  List to index.
 /// @param[in]  n  Index in a list.
 ///
-/// @return [allocated] Copy of the list item string value.
-const char *tv_list_find_str(list_T *l, int n)
-  FUNC_ATTR_MALLOC
+/// @return List item string value or NULL in case of error.
+const char *tv_list_find_str(list_T *const l, const int n)
+  FUNC_ATTR_WARN_UNUSED_RESULT
 {
-  const listitem_T *const li = tv_list_find(l, n - 1);
+  const listitem_T *const li = tv_list_find(l, n);
   if (li == NULL) {
     EMSGN(_(e_listidx), n);
     return NULL;