# File lib/test/unit/assertions.rb, line 1769 def prepare_for_diff(from, to) if !from.is_a?(String) or !to.is_a?(String) from = convert(from) to = convert(to) end if diff_target_string?(from) and diff_target_string?(to) from = ensure_diffable_string(from) to = ensure_diffable_string(to) [from, to] else [nil, nil] end end