add tests, fix type constraints

src/quantities.jl

@@ -283,20 +283,20 @@ _rounderr(f) = error("Specify the type of the quantity to convert to with $f. ",
 if VERSION >= v"1"
     # convenience methods
     round(u::Units, q::Quantity, r::RoundingMode=RoundNearest; kwargs...) = round( numtype(q), u, q, r; kwargs...)
-    round(::Type{T}, u::Units, q::Quantity, r::RoundingMode=RoundNearest; kwargs...) =  round(Quantity{T, dimension(q), typeof(u)}, q, r; kwargs...)
+    round(::Type{T}, u::Units, q::Quantity, r::RoundingMode=RoundNearest; kwargs...) where {T<:Number} =  round(Quantity{T, dimension(q), typeof(u)}, q, r; kwargs...)
     # working horse methods
     round(x::AbstractQuantity, r::RoundingMode=RoundNearest; kwargs...) = _rounderr(:round)
     round(x::DimensionlessQuantity, r::RoundingMode=RoundNearest; kwargs...) = round(uconvert(NoUnits, x), r; kwargs...)
     round(::Type{T}, x::AbstractQuantity, r=RoundingMode=RoundNearest; kwargs...) where {T <: Integer} = _dimerr(:round)
     round(::Type{T}, x::DimensionlessQuantity, r::RoundingMode=RoundNearest; kwargs...) where {T <: Integer} = round(T, uconvert(NoUnits, x), r; kwargs...)
-    round(::Type{T}, x::Quantity, r::RoundingMode=RoundNearest; kwargs...) where {T <: Integer} = T(round(uconvert(unit(T),x).val, r; kwargs...))
+    round(::Type{T}, x::Quantity, r::RoundingMode=RoundNearest; kwargs...) where {T <: Quantity} = T(round(ustrip(uconvert(unit(T),x)), r; kwargs...))
     # that should actually be fixed in Base ↓
     trunc(x::AbstractQuantity; kwargs...) = round(x, RoundToZero; kwargs...)
     floor(x::AbstractQuantity; kwargs...) = round(x, RoundDown; kwargs...)
     ceil(x::AbstractQuantity; kwargs...)  = round(x, RoundUp; kwargs...)
-    trunc(t::Type{T}, x::AbstractQuantity; kwargs...) where {T<:Integer} = round(t, x, RoundToZero)
-    floor(t::Type{T}, x::AbstractQuantity) where {T<:Integer} = round(t, x, RoundDown)
-    ceil(t::Type{T}, x::AbstractQuantity)  where {T<:Integer} = round(t, x, RoundUp)
+    trunc(::Type{T}, x::AbstractQuantity; kwargs...) where {T<:Number} = round(T, x, RoundToZero; kwargs...)
+    floor(::Type{T}, x::AbstractQuantity; kwargs...) where {T<:Number} = round(T, x, RoundDown; kwargs...)
+    ceil(::Type{T}, x::AbstractQuantity; kwargs...)  where {T<:Number} = round(T, x, RoundUp; kwargs...)
 else
     for f in (:floor, :ceil, :trunc, :round)
         @eval ($f)(x::AbstractQuantity; digits=0) = _dimerr($f)

test/runtests.jl

@@ -901,6 +901,8 @@ end
         @test round(typeof(1mm), 1.0314m) === 1031mm
         @test round(typeof(1.0mm), 1.0314m) === 1031.0mm
         @test round(typeof(1.0mm), 1.0314m; digits=1) === 1031.4mm
+        @test round(u"inch", 1.0314m) === 41.0u"inch"
+        @test round(Int, u"inch", 1.0314m) === 41u"inch"
     end
 end