It's not too difficult to have MarkUs populated with a bunch of students, assignments, TA's, etc, while you're testing.
Sometimes, it's nice to just drop it all and start fresh, with a few users, and a few assignments.
Here's how you can do it quickly and easily.
First, open the command line, and change directories to the root of your local MarkUs copy.
Next, type in the following to reset your database:
$> bundle exec rake db:reset
This will drop the database, recreate it, and load the latest version of the schema that was in db/schema.rb. Finally, you can (optionally) populate the database with some quick and dirty records to get you going:
$> bundle exec rake db:seed
This runs the Ruby scripts in db/seed.rb.