Generally, just type a slash followed by the exact name of your glyph. An example would be /A.alt2. The easy way is to select all the glyphs you have created as alternates and then select "copy"; past the results into a text editor. From here you can search and replace the slash with "slash-testing neighbor glyph-slash" [sub /A.alt/B.alt, etc with sub /O/V/T/, etc. You can build test strings quite quickly this way. If you always use the same naming system, you can use the test strings, over, and over.