RSpec Rails Validation Helper

validation_helpers.rb

# Examples:
# test_valid_attribute Link, :url => 'http://example.com'
# test_invalid_attribute Link, :url => 'OH NOES!!!1!'

module ValidationHelpers
  def test_valid_attribute(model, attr_val_hash)
    test_attribute(:valid, model, attr_val_hash)
  end

  def test_invalid_attribute(model, attr_val_hash)
    test_attribute(:invalid, model, attr_val_hash)
  end

  def test_attribute(test, model, attr_val_hash)
    test_methods = {:valid => :should, :invalid => :should_not}
    raise ArgumentError, 'unsupported test type' unless test_methods.keys.include?(test)

    object = model.new(attr_val_hash)
    object.valid?
    
    attr_val_hash.keys.each do |attr|
      object.errors[attr].send(test_methods[test], be_empty)
    end
  end
end