带有间隔的伪造日期数据，用于RSpec测试

问题描述

我正在使用Faker和Factory_bot Gems为我的RSpec测试生成一些虚假数据，并且我需要为它们每个生成1小时的间隔，例如：

约会模型具有开始日期和结束日期，并且它们之间应相差一小时。例如：

开始日期：“ 2020-10-20 19:51:00” 结束日期：“ 2020-10-20 20:51:00”

这是我目前的工厂：

  factory :appointment do
    start_date { Faker::Date.between(from: 2.year.ago,to: Date.today) }
    end_date { Faker::Date.between(from: 2.year.ago,to: Date.today) }
    user_id nil
    therapist_id nil
  end

我想知道如何存储最初生成的虚假数据并向其中添加一个小时。

解决方法

首先介绍一些FactoryBot和Rails技巧。

Do not use Date.today in Rails,it is not aware of time zones。使用Time.zone.today。而且这些是时间，而不是日期，因此Time.current更合适。最后，除非您所有的约会都过去了，否则请使用2.years.since。

时间戳的约定是以_at结尾。 start_at和end_at。这也避免了对start_date是时间而不是日期的困惑。

---

我们可以利用ActiveSupport::Duration及其Numeric extensions来添加到开始日期。 end_date { start_date + 1.hour }。

我们可以使用trait来使假设明确，​​而不是将特定测试的假设硬编码到工厂中。

factory :appointment do
  # These are the normal conditions.
  # end_at will be 15 to 180 minutes after start_at.
  start_at { Faker::Time.between(from: 2.years.ago,to: 2.years.since) }
  end_at { start_at + rand(15..180).minutes }

  # This is a specific trait putting end_at an hour after start_at.
  trait :in_one_hour do
    end_at { start_at + 1.hour }
  end
end

# An appointment of 1 hour which started yesterday
appointment = build(:appointment,:in_one_hour,start_at: 1.day.ago)

我们可以做得更好。如果我们想要不同的持续时间怎么办？可以使用transient attribute代替特征。这使您可以将属性发送给工厂，而不是对象的属性。像持续时间一样。

factory :appointment do
  transient do
    duration { rand(15..180).minutes }
  end

  start_at { Faker::Time.between(from: 2.years.ago,to: 2.years.since) }
  end_at { start_at + duration }
end

# An appointment with a random but reasonable duration.
p build(:appointment)

# An appointment with a duration of exactly 1 hour.
p build(:appointment,duration: 1.hour)

# An appointment lasting 30 minutes starting yesterday.
p build(:appointment,duration: 30.minutes,start_at: 1.day.ago)

有问题。如果呼叫者更改了end_at怎么办？然后，start_at应该基于end_at。但是，如果它们设置了start_at，则end_at必须基于start_at。这导致了循环定义。

factory :appointment do
  transient do
    duration { rand(15..180).minutes }
  end

  # Circular
  start_at { end_at + duration }
  end_at { start_at - duration }
end

我们需要使用callback来避免循环依赖。

factory :appointment do
  transient do
    duration { rand(15..180).minutes }
  end
      
  after(:build) do |appointment,evaluator|
    case
    when appointment.start_at && appointment.end_at
      # The user set both,leave them be.
    when appointment.start_at
      # The user set only the start_at.
      appointment.end_at ||= appointment.start_at + evaluator.duration
    when appointment.end_at
      # The user set only the end_at.
      appointment.start_at ||= appointment.end_at - evaluator.duration
    else
      # The user set neither.
      appointment.start_at = Faker::Time.between(from: 2.years.ago,to: 2.years.since)
      appointment.end_at = appointment.start_at + evaluator.duration
    end
  end
end

p build(:appointment)
p build(:appointment,duration: 1.hour,start_at: 1.year.ago)
p build(:appointment,end_at: 1.year.since)
p build(:appointment,start_at: 1.year.ago,end_at: 1.year.since)

最后，如果您使用的是Postgres，请you can merge start_at and end_at into a single range column。这使用Postgres's tstzrange type，Rails将在两次之间将其转换为Range。与开始和结束时间戳记相比，这可能要容易得多。

factory :appointment do
  transient do
    duration { rand(15..180).minutes }
  end
        
  timespan do
    start_time = Faker::Time.between(from: 2.years.ago,to: 2.years.since)
    end_time = start_time + duration
    (start_time..end_time)
  end
end

p FactoryBot.build(:appointment)
p FactoryBot.build(:appointment,duration: 1.hour)
p FactoryBot.build(:appointment,timespan: (1.year.ago..Time.current))