I actually should be this way:

``` javascript
assert.equal(lib_util.join('a/', '/b'), '/b');
assert.equal(lib_util.join("http://example.com/foo", "/bar"), "http://example.com/bar");
assert.equal(lib_util.join("http://example.com/foo", "//bar"), "http://bar");
assert.equal(lib_util.join("https://example.com/foo", "//bar.com/foo"), "https://bar.com/foo");
```