module SimpleAssertions
  module AssertErrorsOn
    # Assert errors on given parameters.
    # It calls #valid? on +object+ unless called with a block.
    #
    # == Example
    #
    #   assert_errors_on record, :email
    #   assert_errors_on record, :email => 2
    #   assert_errors_on record, :email => "can't be blank"
    #   assert_errors_on record, :email => :"errors.messages.blank"
    #   assert_errors_on record, :email => :"errors.attributes.email.blank"
    #   assert_errors_on record, :email => /blank/
    #   assert_errors_on record, :email => ["can't be blank", "is invalid"]
    #   assert_errors_on record, :email, :plz => 2
    #   assert_errors_on record, [:username, :email] => "can't be blank"
    #
    #   assert_errors_on record, :email => 1 do
    #     assert !record.save
    #   end
    #
    # Based on http://gist.github.com/49013
    def assert_errors_on(object, *attributes_or_hash)
      if block_given?
        yield
      else
        assert !object.valid?, "#{object.inspect} should be invalid."
      end

      hash = attributes_or_hash.last.is_a?(Hash) ? attributes_or_hash.pop : {}
      attributes_or_hash.each { |field| hash[field] ||= 1 }

      hash.each do |fields, pattern|
        Array(fields).each do |field|
          errors = Array(object.errors[field])

          case pattern
          when Fixnum
            assert_equal pattern, errors.size,
                         "#{pattern} error(s) expected for #{object.class}.#{field} but got #{errors.inspect}."
          when Regexp
            assert errors.any? && errors.all? { |message| pattern.match(message) },
                   "expected to match #{pattern} for #{object.class}.#{field} but got #{errors.inspect}."
          when String
            assert_equal [pattern], errors,
                         "#{pattern.inspect} expected for #{object.class}.#{field} but got #{errors.inspect}."
          when Symbol
            translation = I18n.t(pattern)
            assert_equal [translation], errors,
                         "#{pattern.inspect}(#{translation}) expected for #{object.class}.#{field} but got #{errors.inspect}."
          when Array
            assert_equal pattern.sort, errors.sort,
                         "#{pattern.inspect} expected for #{object.class}.#{field} but got #{errors.inspect}."
          else
            flunk "unknown matcher type #{pattern.class}: #{pattern.inspect}"
          end
        end
      end
    end
  end
end