rails でmailにimageを入れてるときのLinkのrspecのテスト

imageがない場合

spec/mailers/email_spec.rb

let(:mail) { described_class.send_email(user)}
it 'assigns activation url' do
  url = something_url(user)
  expect(mail.body.encoded).to have_link(t('activate'), href: url)
end

画像を入れる

app/helpers/email_helper.rb

module EmailHelper
  def email_image_tag(image, options = {})
    image_tag email_image_url(image), options
  end

  def email_image_url(image)
    attachments[image] = File.read Rails.root.join("app/assets/images/#{image}")
    attachments[image].url
  end
end

app/views/user_mailer/send_mail.haml

...
= email_image_tag('test.png') # app/assets/image/test.png
...

画像を入れるとContent-typeが変わってしまい、上記のURLのテストがうまくいかない

解決方法

spec/supports/email_helper.rb

module EmailHelper
  def get_message_part(mail, content_type)
    mail.body.parts.find { |p| p.content_type.match content_type }
        .body.raw_source
  end
end

spec/mailers/email_spec.rb

include EmailHelper
let(:mail) { described_class.send_email(user)}
let(:msg) { get_message_part mail, /html/ }
it 'assigns activation url' do
  url = something_url(user)
  expect(msg).to have_link(t('activate'), href: url)
end