Round to nonpositive resolution throws DomainError

Throw DomainError on rounding to an invalid (non-positive) resolution
Clean up test cases for rounding dates that don't need rounding
Add test cases for rounding to invalid (non-positive) resolutions

base/dates/rounding.jl

@@ -38,11 +38,13 @@ Takes the given `DateTime` and returns the number of milliseconds since the roun
 datetime2epochms(dt::DateTime) = value(dt) - DATETIMEEPOCH
 
 function Base.floor(dt::Date, p::Year)
+    value(p) < 1 && throw(DomainError())
     years = year(dt)
     return Date(years - mod(years, value(p)))
 end
 
 function Base.floor(dt::Date, p::Month)
+    value(p) < 1 && throw(DomainError())
     y, m = yearmonth(dt)
     months_since_epoch = y * 12 + m - 1
     month_offset = months_since_epoch - mod(months_since_epoch, value(p))
@@ -52,19 +54,22 @@ function Base.floor(dt::Date, p::Month)
 end
 
 function Base.floor(dt::Date, p::Week)
+    value(p) < 1 && throw(DomainError())
     days = value(dt) - WEEKEPOCH
     days = days - mod(days, value(Day(p)))
     return Date(UTD(WEEKEPOCH + Int64(days)))
 end
 
 function Base.floor(dt::Date, p::Day)
+    value(p) < 1 && throw(DomainError())
     days = date2epochdays(dt)
     return epochdays2date(days - mod(days, value(p)))
 end
 
 Base.floor(dt::DateTime, p::DatePeriod) = DateTime(Base.floor(Date(dt), p))
 
 function Base.floor(dt::DateTime, p::TimePeriod)
+    value(p) < 1 && throw(DomainError())
     milliseconds = datetime2epochms(dt)
     return epochms2datetime(milliseconds - mod(milliseconds, value(Millisecond(p))))
 end

test/dates/rounding.jl

@@ -111,33 +111,12 @@ dt = Dates.DateTime(-1, 12, 29, 19, 19, 19, 19)
 @test ceil(dt, Dates.Second(2)) == DateTime(-1, 12, 29, 19, 19, 20)
 
 # Test rounding for dates that should not need rounding
-dt = Dates.DateTime(2016, 1, 1)
-@test floor(dt, Dates.Year) == dt
-@test floor(dt, Dates.Month) == dt
-@test floor(dt, Dates.Day) == dt
-@test floor(dt, Dates.Hour) == dt
-@test floor(dt, Dates.Minute) == dt
-@test floor(dt, Dates.Second) == dt
-@test ceil(dt, Dates.Year) == dt
-@test ceil(dt, Dates.Month) == dt
-@test ceil(dt, Dates.Day) == dt
-@test ceil(dt, Dates.Hour) == dt
-@test ceil(dt, Dates.Minute) == dt
-@test ceil(dt, Dates.Second) == dt
-
-dt = Dates.DateTime(-2016, 1, 1)
-@test floor(dt, Dates.Year) == dt
-@test floor(dt, Dates.Month) == dt
-@test floor(dt, Dates.Day) == dt
-@test floor(dt, Dates.Hour) == dt
-@test floor(dt, Dates.Minute) == dt
-@test floor(dt, Dates.Second) == dt
-@test ceil(dt, Dates.Year) == dt
-@test ceil(dt, Dates.Month) == dt
-@test ceil(dt, Dates.Day) == dt
-@test ceil(dt, Dates.Hour) == dt
-@test ceil(dt, Dates.Minute) == dt
-@test ceil(dt, Dates.Second) == dt
+for dt in [Dates.DateTime(2016, 1, 1), Dates.DateTime(-2016, 1, 1)]
+    for p in [Dates.Year, Dates.Month, Dates.Day, Dates.Hour, Dates.Minute, Dates.Second]
+        @test floor(dt, p) == dt
+        @test ceil(dt, p) == dt
+    end
+end
 
 # Test available RoundingModes
 dt = Dates.DateTime(2016, 2, 28, 12)
@@ -148,3 +127,13 @@ dt = Dates.DateTime(2016, 2, 28, 12)
 @test_throws DomainError round(dt, Dates.Day, RoundNearestTiesAway)
 @test_throws DomainError round(dt, Dates.Day, RoundToZero)
 @test round(dt, Dates.Day) == round(dt, Dates.Day, RoundNearestTiesUp)
+
+# Test rounding to invalid resolutions
+dt = Dates.DateTime(2016, 2, 28, 12, 15)
+for p in [Dates.Year, Dates.Month, Dates.Week, Dates.Day, Dates.Hour]
+    for v in [-1, 0]
+        @test_throws DomainError floor(dt, p(v))
+        @test_throws DomainError ceil(dt, p(v))
+        @test_throws DomainError round(dt, p(v))
+    end
+end