Cook the pasta according to the instructions on the box. Check one minute before to get al dente pasta. Cool in the fridge or freezer until the steam stops and it's not too hot to touch.
In a large bowl, mix the black beans, cherry tomatoes, corn, cilantro, green onions, chipotle lime greek yogurt ranch and lime together.
Toss in the diced avocado just before serving. If you aren't eating the entire batch at one time only toss the avocado with the part you are eating.
If you are making this ahead of time, considering tossing it with the dressing at the last minute so it will remain creamy.