# RSpec (Adding Data to Test)

### Fixtures
運作方式：使用YAML檔將資料直接塞入資料庫中，並轉換成ActiveRecord物件。（可以快速建構全域資料）
1. 資料庫中必須有相對應的欄位
2. 並不受ActiveRecord的驗證影響
3. Fixture會在測試一開始建立完成，測試完後會將過程rolled back

##### 優點
1. 運行速度快
2. 假資料會一直存在
##### 缺點
1. Fixture資料是全域的
2. 關聯性需要自己建立
3. 無法立即了解資料建立步驟
4. Fixture資料是脆弱的

---

### Factories
運作方式：
1. build(:project)：回傳model instance，但並不會存進資料庫中
2. create(:project)：回傳model instance，會存進資料庫中
3. attributes_for(:project)：回傳物件屬性的hash值
4. build_stubbed(:project)：很像build，但會給一個假的ActiveRecord ID

方法：
*_pair：使用factory建立出兩個物件 ex: create_pair(:project)
*_list：使用factory建立出多個物件 ex: create_list(:project, 5)

##### Inherited Factories

FactoryBot.define do
    factory :task do
        sequence(:title) {|n| "Task #{n}"}
    end
    
    factory :big_task, parent: :task do
        size 5
    end
    
    factory :small_task, parent: :task do
        size 1
    end
end

FactoryBot.define do
    factory :task do
        sequence(:title) {|n| "Task #{n}"}
        size 3
        completed_at nil
    end
    
    trait :small do
        size 1
    end
    
     trait :large do
        size 5
    end
end

##### Dates and Times

let(:runway){create(:proect, name: "Project Runway", start_date: "2018-01-20")}

let(:greenlight){create(:proect, name: "Project Greenlight", start_date: "2018-02-24")}

let(:gutenberg){create(:proect, name: "Project Gutenberg", start_date: "2018-01-31")}

it "finds recently started projects" do
    actual = Project.find_recently_started(6.months)
    expect(actual.size).to eq(3)
end

六個月後測試就過不了

解決方法：
1. Relative Dates

let(:runway){create(:proect, name: "Project Runway", start_date: 1.week.ago)}

let(:greenlight){create(:proect, name: "Project Greenlight", start_date: 1.month.ago)}

let(:gutenberg){create(:proect, name: "Project Gutenberg", start_date: 1.day.ago)}

it "finds recently started projects" do
    actual = Project.find_recently_started(6.months)
    expect(actual.size).to eq(3)
end

2. Stubbing time
ActiveSupport::Testing::TimeHelpers#travel
ActiveSupport::Testing::TimeHelpers#travel_to

#travel_to
it "finds recently started projects" do
    travel_to(Date.parse("2018-02-10"))
    actual = Project.find_recently_started(6.months)
    expect(actual.size).to eq(3)
end

#travel
it "knows if the project is over" do
    p = Project.new(:start_date => Date.today, :end_date =                            Date.today + 8.weeks)
    expect(p).not_to be_complete
    teavel(10.weeks)
    expect(p).to be_complete
end