1) Error:
test_should_not_generate_an_error(QueueEntryTest):
TypeError: wrong argument type nil (expected Data)
    /opt/local/lib/ruby/1.8/yaml.rb:387:in `emit'
    /opt/local/lib/ruby/1.8/yaml.rb:387:in `quick_emit'
    /opt/local/lib/ruby/1.8/yaml/rubytypes.rb:38:in `to_yaml'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb:31:in `quote'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb:330:in `quote'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/base.rb:2051:in `quote_value'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/base.rb:2042:in `attributes_with_quotes'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/callbacks.rb:309:in `inject'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/base.rb:2040:in `each'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/base.rb:2040:in `inject'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/base.rb:2040:in `attributes_with_quotes'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/base.rb:2133:in `quoted_column_names'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/base.rb:1980:in `create_without_callbacks'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/callbacks.rb:226:in `create_without_timestamps'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/timestamp.rb:29:in `create'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/base.rb:1956:in `create_or_update_without_callbacks'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/callbacks.rb:213:in `create_or_update'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/base.rb:1716:in `save_without_validation!'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/validations.rb:884:in `save_without_transactions!'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/transactions.rb:109:in `save!'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:66:in `transaction'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/transactions.rb:77:in `transaction'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/transactions.rb:97:in `transaction'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/transactions.rb:109:in `save!'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/transactions.rb:117:in `rollback_active_record_state!'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/transactions.rb:109:in `save!'
    /Users/jonathanwallace/rollbook/trunk/vendor/rails/activerecord/lib/active_record/validations.rb:849:in `create!'
    /Users/jonathanwallace/rollbook/trunk/app/models/queue_entry.rb:120:in `log_action'
    /Users/jonathanwallace/rollbook/trunk/app/models/queue_entry.rb:91:in `log_completed_action'
    /Users/jonathanwallace/rollbook/trunk/app/models/queue_entry.rb:84:in `execute_action'
    ./test/unit/queue_entry_test.rb:285:in `test_should_not_generate_an_error'
    /opt/local/lib/ruby/gems/1.8/gems/mocha-0.5.5/lib/mocha/test_case_adapter.rb:19:in `__send__'
    /opt/local/lib/ruby/gems/1.8/gems/mocha-0.5.5/lib/mocha/test_case_adapter.rb:19:in `run'

here's the hash that is generating the error: 

"{:enrollment_params=>{:due_on=>Wed Dec 05 13:54:26 -0500 2007}, :enrollment_ids=>[#, updated_by: ni
l, updated_on: \"2007-12-05 13:54:32\", expires_on: nil, auto_enrollment_id: nil>]}"