Add eps for ZonedDateTime (#148)

src/accessors.jl

@@ -1,3 +1,4 @@
+import Base: eps
 import Compat.Dates: Hour, Minute, Second, Millisecond,
     days, hour, minute, second, millisecond
 
@@ -33,3 +34,5 @@ for period in (:Hour, :Minute, :Second, :Millisecond)
         $period(zdt::ZonedDateTime) = $period($accessor(zdt))
     end
 end
+
+eps(::ZonedDateTime) = Millisecond(1)

src/discovery.jl

@@ -212,7 +212,8 @@ show_next_transition
 
 function show_next_transition(io::IO, zdt::ZonedDateTime)
     instant = next_transition_instant(zdt)
-    from, to = instant - Millisecond(1), instant + Millisecond(0)
+    epsilon = eps(instant)
+    from, to = instant - epsilon, instant + zero(epsilon)
     direction = value(to.zone.offset - from.zone.offset) < 0 ? "Backward" : "Forward"
 
     function zdt_format(zdt)

test/accessors.jl

@@ -1,5 +1,5 @@
 import Compat.Dates
-import Compat.Dates: Second
+import Compat.Dates: Second, Millisecond
 
 warsaw = resolve("Europe/Warsaw", tzdata["europe"]...)
 fixed = FixedTimeZone("Fixed", -7200, 3600)
@@ -15,6 +15,8 @@ zdt = ZonedDateTime(DateTime(2014,6,12,23,59,58,57), fixed)
 @test TimeZones.second(zdt) == 58
 @test TimeZones.millisecond(zdt) == 57
 
+@test eps(zdt) == Millisecond(1)
+
 # Make sure that Dates accessors work with ZonedDateTime.
 @test Dates.year(zdt) == 2014
 @test Dates.month(zdt) == 6