RSpec::Matchers.define :ensure_valid_alpha_format_of do |attribute| match do |model| model.send("#{attribute}=", "$1234.56") model.valid? if model.errors.has_key?(attribute) model.errors[attribute].include?(I18n.t('errors.messages.alpha')) end end failure_message do |model| I18n.t('flash_validators.matchers.ensure_valid_alpha_format_of.failure_message_for_should', model: model.class) end failure_message_when_negated do |model| I18n.t('flash_validators.matchers.ensure_valid_alpha_format_of.failure_message_for_should_not', model: model.class) end end