Add really basic test

Author: pynappo

tests/neo-tree/utils/fs_spec.lua

@@ -6,5 +6,6 @@ describe("fs_parent", function()
     assert.are.same(nil, utils.fs_parent("/"))
     assert.are.same("/", utils.fs_parent("/foo"))
     assert.are.same("/", utils.fs_parent("/foo/bar", true))
+    assert.are.same(nil, utils.fs_parent("/foo/bar", false))
   end)
 end)