```ruby
require File.dirname(File.expand_path(__FILE__)) + '/test_helper'

describe AttributeNormalizer do

  it 'should add the class method Class#normalize_attributes and Class#normalize_attribute when included' do
    klass = Class.new do
      include AttributeNormalizer
    end

    klass.should respond_to(:normalize_attributes)
    klass.should respond_to(:normalize_attribute)
  end

end```

Add spec to simulate table_exists? throwing a database adapter exception
user
```ruby
require File.dirname(File.expand_path(__FILE__)) + '/test_helper'

describe AttributeNormalizer do

  it 'should add the class method Class#normalize_attributes and Class#normalize_attribute when included' do
    klass = Class.new do
      include AttributeNormalizer
    end

    klass.should respond_to(:normalize_attributes)
    klass.should respond_to(:normalize_attribute)
  end

  it 'should not fail due to database exceptions raised by table_exists?' do
    class PGError < RuntimeError; end
    
    Class.new(ActiveRecord::Base) do
      def self.table_exists?
        raise PGError, "FATAL:  something bad happened trying to probe for table existence"
      end
      
      include AttributeNormalizer
    end
    
  end
end```
assistant