In the next checkpoint,we’ll add a Vote model. This model will
feature an inclusion validation. Inclusion validation ensures that a
vote’s value attribute is either 1 or -1. If a vote is initialized
with any other value,it will not save.

1. Create VoteSpec:

规格/型号/ vote_spec.rb

describe Vote do
  describe "validations" do
    describe "value validation" do
      it "only allows -1 or 1 as values" do
        # your expectations here
      end
    end
  end
end

Write a spec that asserts the validations work as expected.

Use RSpec’s expect().to eq() Syntax. As you may recall from the specs in
the Ruby exercises,you can assert that something should equal false
or true.

You won’t be able to run the tests because we haven’t
generated the model we’re testing.

以下是我的实施：

describe Vote do
  describe "validations" do

    before do     
      2.times { @vote.create(value: 1) }
      3.times { @vote.create(value: -1) }
      2.times { @vote.create(value: 3) }
    end

    describe "value validation" do 
      it "only allows -1 or 1 as values" do
        expect ( @vote.value ).to eq(-1)
      end

      it "only allows -1 or 1 as values" do
        expect ( @vote.value ).to eq(1)
      end
    end
  end
end

最好的祝福.

编辑：这是一个修订版：

describe Vote do
  describe "validations" do

    before do     
      2.times { Vote.create(value: 1) }
      3.times { Vote.create(value: 0) }
      2.times { Vote.create(value: 3) }
    end

    describe "value validation" do 
      it "only allows -1 as value" do
        expect ( @vote.value ).to eq(-1)
      end
      it "only allows 1 as value" do
        expect ( @vote.value ).to eq(1)
      end

      it "it prohibits other values" do
        expect( @vote.value ).to_not be_valid
      end
    end
  end
end

我也试过这个代码,它起初工作但现在在下一个任务中失败了：

require 'rails_helper'

  describe Vote do
   describe "value validation" do

      it "allows -1" do
        value = Vote.create(value: -1)
        expect(value).to be_valid
      end

      it "allows +1" do
        value = Vote.create(value: +1)
        expect(value).to be_valid
      end

      it "prohibits other values" do
        value = Vote.create(value: 0)
        expect(value).to_not be_valid
      end

    end
end

▶ rspec spec
...FFF

Failures:

  1) Vote value validation allows -1
     Failure/Error: value = Vote.create(value: -1)
     NoMethodError:
       undefined method `update_rank' for nil:NilClass
     # ./app/models/vote.rb:12:in `update_post'
     # ./spec/models/vote_spec.rb:7:in `block (3 levels) in <top (required)>'

  2) Vote value validation allows +1
     Failure/Error: value = Vote.create(value: +1)
     NoMethodError:
       undefined method `update_rank' for nil:NilClass
     # ./app/models/vote.rb:12:in `update_post'
     # ./spec/models/vote_spec.rb:12:in `block (3 levels) in <top (required)>'

  3) Vote value validation prohibits other values
     Failure/Error: expect(value).to eq(false)

       expected: false
            got: #<Vote id: nil,value: 0,user_id: nil,post_id: nil,created_at: nil,updated_at: nil>

       (compared using ==)
     # ./spec/models/vote_spec.rb:18:in `block (3 levels) in <top (required)>'

Finished in 0.30485 seconds (files took 3.28 seconds to load)
6 examples,3 failures

Failed examples:

rspec ./spec/models/vote_spec.rb:6 # Vote value validation allows -1
rspec ./spec/models/vote_spec.rb:11 # Vote value validation allows +1
rspec ./spec/models/vote_spec.rb:16 # Vote value validation prohibits other values