ensure that there is at least one trailing slash at the end.

import { assertEquals } from "jsr:@std/assert"

// aliasing our functions for brevity
const eq = assertEquals, fn = ensureEndSlash

eq(fn("///a/b.zip//"), "///a/b.zip//")
eq(fn(".///../a/b.zip/"), ".///../a/b.zip/")
eq(fn(".///../a/b.zip/."), ".///../a/b.zip/./")
eq(fn(".///../a/b.zip/./"), ".///../a/b.zip/./")
eq(fn(".///../a/b.zip/.."), ".///../a/b.zip/../")
eq(fn(".///../a/b.zip/../"), ".///../a/b.zip/../")
eq(fn("file:///a/b.zip//c.txt"), "file:///a/b.zip//c.txt/")