dry-validation-i18n.rb

require 'i18n'
require 'dry-validation'
require 'dry/validation/version'

puts "dry-validation version: #{Dry::Validation::VERSION}"
puts "\n\n#{'#' * 20} \n\n"

I18n.backend.store_translations(:'zh-CN', {errors: {str?: '必须是字符串'}})

schema = Dry::Validation.Schema do
    configure {
          config.messages = :i18n
            }
      required(:email).filled(:str?)
end

def show_message(schema)
  puts "I18n.locale is #{I18n.locale}"
  result = schema.(email: 122)
  puts "result messages: #{result.messages}"
  puts "result messages(explicit locale) #{result.messages(locale: I18n.locale)}"
  puts "I18n.t: #{I18n.t("errors.str?")}"
  puts "#{result.messages[:email].first == I18n.t('errors.str?') }"
end

show_message(schema)
puts "\n\n#{'#' * 20} \n\n"
I18n.locale = :'zh-CN'
show_message(schema)

message_spec.rb

require 'rspec'
require 'i18n'
require 'dry-validation'
require 'dry/validation/version'

context "I18n Message" do
  before do
    I18n.backend.store_translations(:'zh-CN', {errors: {str?: '必须是字符串'}})
  end
  let!(:schema) do
    schema = Dry::Validation.Schema do
      configure {
        config.messages = :i18n
      }
      required(:email).filled(:str?)
    end
  end

  context "en(default) locale" do
    it do
      expect_message = 'must be a string'
      result = schema.(email: 122)
      result_message = result.messages[:email].first
      result_message_explict_locale = result.messages(locale: I18n.locale)[:email].first
      i18n_message = I18n.t("errors.str?")
      expect(result_message).to eq(expect_message)
      expect(result_message).to eq(result_message_explict_locale)
      expect(result_message).to eq(i18n_message)
    end
  end

  context "zh-CN locale" do
    it do
      I18n.locale = :'zh-CN'
      expect_message = '必须是字符串'
      result = schema.(email: 122)
      result_message = result.messages[:email].first
      result_message_explict_locale = result.messages(locale: I18n.locale)[:email].first
      i18n_message = I18n.t("errors.str?")
      expect(i18n_message).to  eq(expect_message)   # pass
      expect(result_message_explict_locale).to  eq(expect_message) # pass
      expect(result_message).to eq(expect_message)  # fail
      expect(result_message).to eq(i18n_message)    # fail
    end
  end
end

the console output

dry-validation version: 0.10.3


####################

I18n.locale is en
result messages: {:email=>["must be a string"]}
result messages(explicit locale) {:email=>["must be a string"]}
I18n.t: must be a string
true


####################

I18n.locale is zh-CN
result messages: {:email=>["must be a string"]}
result messages(explicit locale) {:email=>["必须是字符串"]}
I18n.t: 必须是字符串
false