Add overflow tests for fld1 and div(::RoundMode)

Author: NHDaly

src/FixedPointDecimals.jl

@@ -367,9 +367,12 @@ end
 if VERSION >= v"1.4.0-"
     # div(x.i, y.i) eliminates the scaling coefficient, so we call the FD constructor.
     # We don't need any widening logic, since we won't be multiplying by the coefficient.
-    @eval function Base.div(x::T, y::T, r::RoundingMode) where {T <: FD}
-        C = coefficient(T)
-        return reinterpret(T, C * div(x.i, y.i, r))
+    @eval function Base.div(x::FD{T, f}, y::FD{T, f}, r::RoundingMode) where {T<:Integer, f}
+        C = coefficient(FD{T, f})
+        # Note: The div() will already throw for divide-by-zero and typemin(T) ÷ -1.
+        v, b = Base.Checked.mul_with_overflow(C, div(x.i, y.i, r))
+        b && _throw_overflowerr_op(:div, x, y)
+        return reinterpret(FD{T, f}, v)
     end
 end
 

test/FixedDecimal.jl

@@ -834,27 +834,33 @@ end
     end
 
     @testset "division" begin
-        # TODO(PR): Is this the expected value?
         @test_throws OverflowError typemax(T) / T(0.5)
         @test_throws OverflowError typemin(T) / T(0.5)
     end
 
     @testset "truncating division" begin
-        # TODO(PR): Is this the expected value?
         @test_throws OverflowError typemax(T) ÷ T(0.5)
         @test_throws OverflowError typemin(T) ÷ T(0.5)
         @test_throws OverflowError typemax(T) ÷ eps(T)
         @test_throws OverflowError typemin(T) ÷ eps(T)
+
+        @test_throws OverflowError div(typemax(T), T(0.5), RoundUp)
+        @test_throws OverflowError div(typemin(T), T(0.5), RoundUp)
+        @test_throws OverflowError div(typemax(T), eps(T), RoundUp)
+        @test_throws OverflowError div(typemin(T), eps(T), RoundUp)
     end
 
     @testset "fld / cld" begin
-        # TODO(PR): Is this the expected value?
         @test_throws OverflowError fld(typemax(T), T(0.5))
         @test_throws OverflowError fld(typemin(T), T(0.5))
         @test_throws OverflowError fld(typemax(T), eps(T))
         @test_throws OverflowError fld(typemin(T), eps(T))
 
-        # TODO(PR): Is this the expected value?
+        @test_throws OverflowError fld1(typemax(T), T(0.5))
+        @test_throws OverflowError fld1(typemin(T), T(0.5))
+        @test_throws OverflowError fld1(typemax(T), eps(T))
+        @test_throws OverflowError fld1(typemin(T), eps(T))
+
         @test_throws OverflowError cld(typemax(T), T(0.5))
         @test_throws OverflowError cld(typemin(T), T(0.5))
         @test_throws OverflowError cld(typemax(T), eps(T))