Tests how switch to next file with the same name and different extension feature works.

Dumping next file for each file:
Next file for http://example.com/foo.css is http://example.com/foo.js.
Next file for http://example.com/foo.js is http://example.com/foo.ts.
Next file for http://example.com/foo.js.map is <none>.
Next file for http://example.com/foo.ts is http://example.com/foo.css.
Next file for http://example.com/bar.css is http://example.com/bar.js.
Next file for http://example.com/bar.js is http://example.com/bar.ts.
Next file for http://example.com/bar.js.map is <none>.
Next file for http://example.com/bar.ts is http://example.com/bar.css.
Next file for http://example.com/baz.css is <none>.
Next file for http://example.com/baz2 is <none>.
Next file for http://example.com/foo/foo.css is http://example.com/foo/foo.js.
Next file for http://example.com/foo/foo.js is http://example.com/foo/foo.ts.
Next file for http://example.com/foo/foo.js.map is <none>.
Next file for http://example.com/foo/foo.ts is http://example.com/foo/foo.
Next file for http://example.com/foo/foo is http://example.com/foo/foo.css.
Next file for http://example.com/bar/foo.css is http://example.com/bar/foo.js.
Next file for http://example.com/bar/foo.js is http://example.com/bar/foo.ts.
Next file for http://example.com/bar/foo.js.map is <none>.
Next file for http://example.com/bar/foo.ts is http://example.com/bar/foo.
Next file for http://example.com/bar/foo is http://example.com/bar/foo.css.