Time#change can now change nanoseconds (:nsec)

Closes #16392.

1 files changed, 13 insertions, 6 deletions

diff --git a/activesupport/lib/active_support/core_ext/time/calculations.rb b/activesupport/lib/active_support/core_ext/time/calculations.rb
index 6a7bf7445a..ab8307429a 100644
--- a/activesupport/lib/active_support/core_ext/time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/time/calculations.rb
@@ -64,11 +64,12 @@ class Time
 
   # Returns a new Time where one or more of the elements have been changed according
   # to the +options+ parameter. The time options (<tt>:hour</tt>, <tt>:min</tt>,
-  # <tt>:sec</tt>, <tt>:usec</tt>) reset cascadingly, so if only the hour is passed,
-  # then minute, sec, and usec is set to 0. If the hour and minute is passed, then
-  # sec and usec is set to 0.  The +options+ parameter takes a hash with any of these
-  # keys: <tt>:year</tt>, <tt>:month</tt>, <tt>:day</tt>, <tt>:hour</tt>, <tt>:min</tt>,
-  # <tt>:sec</tt>, <tt>:usec</tt>.
+  # <tt>:sec</tt>, <tt>:usec</tt>, <tt>:nsec</tt>) reset cascadingly, so if only
+  # the hour is passed, then minute, sec, usec and nsec is set to 0. If the hour
+  # and minute is passed, then sec, usec and nsec is set to 0. The +options+
+  # parameter takes a hash with any of these keys: <tt>:year</tt>, <tt>:month</tt>,
+  # <tt>:day</tt>, <tt>:hour</tt>, <tt>:min</tt>, <tt>:sec</tt>, <tt>:usec</tt>
+  # <tt>:nsec</tt>. Path either <tt>:usec</tt> or <tt>:nsec</tt>, not both.
   #
   #   Time.new(2012, 8, 29, 22, 35, 0).change(day: 1)              # => Time.new(2012, 8, 1, 22, 35, 0)
   #   Time.new(2012, 8, 29, 22, 35, 0).change(year: 1981, day: 1)  # => Time.new(1981, 8, 1, 22, 35, 0)
@@ -80,7 +81,13 @@ class Time
     new_hour  = options.fetch(:hour, hour)
     new_min   = options.fetch(:min, options[:hour] ? 0 : min)
     new_sec   = options.fetch(:sec, (options[:hour] || options[:min]) ? 0 : sec)
-    new_usec  = options.fetch(:usec, (options[:hour] || options[:min] || options[:sec]) ? 0 : Rational(nsec, 1000))
+
+    if new_nsec = options[:nsec]
+      raise ArgumentError, "Can't change both :nsec and :usec at the same time: #{options.inspect}" if options[:usec]
+      new_usec = Rational(new_nsec, 1000)
+    else
+      new_usec  = options.fetch(:usec, (options[:hour] || options[:min] || options[:sec]) ? 0 : Rational(nsec, 1000))
+    end
 
     if utc?
       ::Time.utc(new_year, new_month, new_day, new_hour, new_min, new_sec, new_usec)