Why is PostgreSQL telling me a schema doesn't exist?
===

I am on Chapter 7 of Agile Web Development with Rails (4th edition), and when I run rake test:units, I get the following error:

    rake aborted!
    PG::Error: ERROR: invalid value for parameter "search_path": "public" 
    DETAIL: schema "public" does not exist
    : SET search_path TO public
    
    Tasks: TOP => db:test:load => db:test:purge
    (See full trace by running task with --trace)

I am on a MacBook Pro with OSX 10.7.4. I have Ruby 1.9.3, Rails 3.1.0, Rake 0.9.2.2, and PostgreSQL 9.1. My production, development, and test databases all exist, have been migrated to, and match the names, user, and password in my config/database.yml file. The schema for all of them is public.

Can anyone help me?