在Rails和Rspec中测试before_create字段的唯一性

Question

I have a private method that generates a unique open_id for each user. The open_id is also indexed on the database level. How do I write a model test for uniqueness in RSpec?

before_create: generate_open_id!

def generate_open_id!
      begin
        self.open_id = SecureRandom.base64(64)
      end while self.class.exists?(open_id: self.open_id)
    end

UPDATE: solution based on accepted answer below

def generate_open_id!
      if !self.open_id
        begin
          self.open_id = SecureRandom.base64(64)
        end while self.class.exists?(open_id: self.open_id)
      end
    end

@users = FactoryGirl.create_list(:user, 10)
@user_last = @users.last
subject { @user_last }

it "has a random open_id" do
   base_64_regex = %r{^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?$}
   expect(@user_last.open_id).to match base_64_regex
end

it "has a unique open_id" do
   expect {FactoryGirl.create(:user, open_id: @user_last.open_id)}.to raise_error(ActiveRecord::RecordNotUnique)
end

Answer 1

Refactoring your original code will make testing what you're trying to do much easier. Change your generate_open_id! method to this

def generate_open_id!
  (open_id = SecureRandom.base64(64)) unless open_id
end

And now you can test with the following

# spec/models/some_model_spec.rb
describe SomeModel do
  subject(:some_model){ FactoryGirl.create(:some_model) }

  describe 'open_id attribute' do
    it 'is a random base64 string' do
      base_64_regex = %r{^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?$}
      expect(some_model.open_id).to match base_64_regex
    end

    it 'is unique' do
      expect {FactoryGirl.create(:some_model, open_id: some_model.open_id)}.to raise_error(ActiveRecord::RecordInvalid)
    end
  end
end

Answer 2

You can use SecureRandom.uuid that will generate to you unique strings.

More info here .

Also, you can add validates_uniqueness_of :your_field that will do it for you.