Recently I've been trying to play test my custom character class by running it through a dungeon I developed and ran for a party last year. The class focuses around the idea of collecting monster abilities and spending points to modify your own body with them. The dungeon is largely nature and animal based and I have included a druid and fighter in the play test party for comparison.
This is just a dungeon I made up though, and probably isn't perfect for testing all and every home-brewed class. Are there existing formats for a series of encounters at various levels with which home brewers may play test custom classes?