+Tests for provided utils/helpers.
+
+ $ source $TESTDIR/setup.zsh || return 1
+
+ $ PATH=
+ $ autoenv_prepend_path custom_path
+ $ echo $PATH
+ custom_path
+
+ $ autoenv_prepend_path custom_path
+ $ echo $PATH
+ custom_path
+
+ $ autoenv_prepend_path another_path a_third_one
+ $ echo $PATH
+ a_third_one:another_path:custom_path
+
+ $ autoenv_remove_path another_path a_third_one
+ $ echo $PATH
+ custom_path
+
+ $ autoenv_remove_path does_not_exist
+ [1]
+ $ echo $PATH
+ custom_path
+
+ $ autoenv_remove_path custom_path
+ $ echo PATH:$PATH
+ PATH: