Bug #12196: lib: Date.valid_date? returns incorrect response for negative day

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: 2.2.2
• Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN

[ddoherty03 (Daniel Doherty)]

require 'date'
puts RUBY_VERSION
if Date.valid_date?(2016, 2, -1)
  puts "Valid"
else
  puts "Invalid"
end

This reports 'Valid' for a negative day number.

[zverok (Victor Shepelev)]

From Date::new docs:

The month and the day of month should be a negative or a positive number (as a relative month/day from the end of year/month when negative). They should not be zero.

Date.new(2016,2,-1)
# => #<Date: 2016-02-29 ((2457448j,0s,0n),+0s,2299161j)>

From Date.valid_date? docs:

Returns true if the given calendar date is valid, and false if not.

The latter is pretty brief, yet I assume it means rather "valid params for Date.new" than anything else.

[jeremyevans0 (Jeremy Evans)]

I don't think this is a bug in the code, but I do think we should improve the documentation for valid_date. I've added a pull request to do so: https://github.com/ruby/date/pull/7.

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed

The pull request was merged.