duration.rb in fugit-1.8.1

- old
+ new

@@ -66,13 +66,15 @@
       wee: { a: 'W', r: 'w', i: 'W', s: 7 * DAY_S, I: true, l: 'week' },
       day: { a: 'D', r: 'd', i: 'D', s: DAY_S, I: true, l: 'day' },
       hou: { a: 'h', r: 'h', i: 'H', s: 3600, I: true, l: 'hour' },
       min: { a: 'm', r: 'm', i: 'M', s: 60, I: true, l: 'minute' },
       sec: { a: 's', r: 's', i: 'S', s: 1, I: true, l: 'second' } }.freeze
-    INFLA_KEYS, NON_INFLA_KEYS =
-      KEYS.partition { |k, v| v[:I] }.freeze
 
+    INFLA_KEYS, NON_INFLA_KEYS = KEYS
+      .partition { |k, v| v[:I] }
+      .collect(&:freeze)
+
     def _to_s(key)
 
       KEYS.inject([ StringIO.new, '+' ]) { |(s, sign), (k, a)|
         v = @h[k]
         next [ s, sign ] unless v
@@ -238,11 +240,11 @@
 
         if at[1] > 12
           n, m = at[1] / 12, at[1] % 12
           at[0], at[1] = at[0] + n, m
         elsif at[1] < 1
-          n, m = -at[1] / 12, -at[1] % 12
+          n, m = (-at[1]) / 12 + 1, (11+at[1]) % 12 + 1
           at[0], at[1] = at[0] - n, m
         end
 
         t = ::EtOrbi.make_time(at, t.zone)
       end
@@ -267,10 +269,10 @@
 
       case a
       when Numeric then add_numeric(-a)
       when Fugit::Duration then add_duration(-a)
       when String then add_duration(-self.class.parse(a))
-      when ::Time, ::EtOrbi::EoTime then add_to_time(a)
+      when ::Time, ::EtOrbi::EoTime then opposite.add_to_time(a)
       else fail ArgumentError.new(
         "cannot subtract #{a.class} instance to a Fugit::Duration")
       end
     end
     alias - subtract