比较时间与RSpec的故障 [英] Trouble comparing time with RSpec

问题描述

我使用Ruby on Rails 4和rspec-rails gem 2.14。对于我的对象，我想在控制器动作运行之后，将当前时间与 updated_at 对象属性进行比较，但是我遇到麻烦，因为规范没有通过。也就是说，下面是规范代码：

I am using Ruby on Rails 4 and the rspec-rails gem 2.14. For a my object I would like to compare the current time with the updated_at object attribute after a controller action run, but I am in trouble since the spec does not pass. That is, given the following is the spec code:

it "updates updated_at attribute" do
  Timecop.freeze

  patch :update
  @article.reload
  expect(@article.updated_at).to eq(Time.now)
end

当我运行上面的规范，我得到以下错误：

When I run the above spec I get the following error:

Failure/Error: expect(@article.updated_at).to eq(Time.now)

   expected: 2013-12-05 14:42:20 UTC
        got: Thu, 05 Dec 2013 08:42:20 CST -06:00

   (compared using ==)

如何让规格通过？

：我也尝试了以下（注意 utc 添加）：

it "updates updated_at attribute" do
  Timecop.freeze

  patch :update
  @article.reload
  expect(@article.updated_at.utc).to eq(Time.now)
end

但规格仍然不通过注意got值差异）：

but the spec still does not pass (note the "got" value difference):

Failure/Error: expect(@article.updated_at.utc).to eq(Time.now)

   expected: 2013-12-05 14:42:20 UTC
        got: 2013-12-05 14:42:20 UTC

   (compared using ==)

推荐答案

精度比数据库做的。当从数据库读回值时，它只保留到微秒精度，而内存中的表示精确到纳秒。

Ruby Time object maintains greater precision than the database does. When the value is read back from the database, it’s only preserved to microsecond precision, while the in-memory representation is precise to nanoseconds.

如果你不在乎毫秒的差异，你可以在你的期望的两边做一个to_s / to_i

If you don't care about millisecond difference, you could do a to_s/to_i on both sides of your expectation

expect(@article.updated_at.utc.to_s).to eq(Time.now.to_s)

或

expect(@article.updated_at.utc.to_i).to eq(Time.now.to_i)

请参阅此有关时间不同的更多信息

Refer to this for more information about why the times are different

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