Why is `from_now` wrong when called on a Fixnum?

Question

I need to store some time periods in a yaml file, like this:

test:
testing: <%= 1.month %>

I grab the data in an initializer like this:

Class::TIMES = YAML.load(ERB.new(File.new(Rails.root.join('config', 'times.yml')).read).result)

So far so good. But the times I get from this are always off by a day; testing shows this. For example:

<Tue, 06 Mar 2012> expected but was <Wed, 07 Mar 2012>.

The test line:

assert_equal 1.month.from_now.to_date, @object.finished_at.to_date

Elsewhere, @object's finished_at is set like this:

# duration is from the YAML file
self.finished_at = duration.from_now

It always seems to be off by a day, no matter what time period I put in the YAML file. Why does this happen?

EDIT: This seems to be an issue with Fixnums and from_now:

> 1.month.from_now
 => Tue, 06 Mar 2012 21:05:00 UTC +00:00 

> 1.month.to_i.from_now
 => Wed, 07 Mar 2012 21:05:05 UTC +00:00

Answer 1

When you convert 1.month to an integer it arbitrary sets the duration getting passed into from_now to 2592000 seconds i.e 30 days regardless of what month it is.

I ran into this issue once before. Check out the documentation for the Data and Time Helper Methods .

While these methods provide precise calculation when used as in the examples above(".. 1.month.from_now .."), care should be taken to note that this is not true if the result of months’,years’, etc is converted before use