title: Mysql2::Error: Duplicate entry '' for key 'index_admin_users_on_email' Ruby on Rails Error
body: <p>I am trying to run ruby on rails code that I got from github and I ended up installing mysql using homebrew and then also ended up installing it directly from <a href="http://dev.mysql.com/" rel="noreferrer">http://dev.mysql.com/</a>. It was only then that when I used rake in the application file that the tests began to run. However, now I keep getting this Mysql2::Error: Duplicate entry and I don't understand why. Could it be the fact that I have two mysqls located two different places on my computer? I am not really sure what is causing this problem because all the tables are empty. How can I fix this problem? Thank you for helping. I am new to Ruby on Rails and Mysql. </p>
  
  <p>The stack looks like the following:</p>
  
  <pre><code>HomeControllerTest
   test_should_get_index                                               ERROR
      Mysql2::Error: Duplicate entry '' for key 'index_admin_users_on_email': INSERT INTO `admin_users` (`created_at`, `updated_at`, `id`) VALUES ('2011-12-09 09:33:30', '2011-12-09 09:33:30', 298486374)
      STDERR:
      Exception `ActiveRecord::RecordNotUnique' at /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/connection_adapters/mysql2_adapter.rb:283:in `query'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/connection_adapters/mysql2_adapter.rb:283:in `block in execute'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract_adapter.rb:244:in `block in log'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/notifications/instrumenter.rb:21:in `instrument'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract_adapter.rb:239:in `log'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/connection_adapters/mysql2_adapter.rb:283:in `execute'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract/database_statements.rb:302:in `insert_fixture'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/fixtures.rb:486:in `block (5 levels) in create_fixtures'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/fixtures.rb:485:in `each'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/fixtures.rb:485:in `block (4 levels) in create_fixtures'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/fixtures.rb:484:in `each'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/fixtures.rb:484:in `block (3 levels) in create_fixtures'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/fixtures.rb:476:in `each'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/fixtures.rb:476:in `block (2 levels) in create_fixtures'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract/database_statements.rb:192:in `transaction'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/fixtures.rb:475:in `block in create_fixtures'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/connection_adapters/mysql2_adapter.rb:202:in `disable_referential_integrity'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/fixtures.rb:460:in `create_fixtures'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/fixtures.rb:924:in `load_fixtures'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.3/lib/active_record/fixtures.rb:890:in `setup_fixtures'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/callbacks.rb:413:in `_run_setup_callbacks'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/callbacks.rb:81:in `run_callbacks'
      /Users/nick01s/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/testing/setup_and_teardown.rb:34:in `run'
  </code></pre>