Update

Author: raphasampaio

test/test_inplace_operations.jl

@@ -353,6 +353,7 @@ using Test
         Base.:*(a::CustomNumber, b::CustomNumber) = CustomNumber(a.value * b.value)
         Base.convert(::Type{CustomNumber}, x::CustomNumber) = x
         Base.zero(::Type{CustomNumber}) = CustomNumber(0.0)
+        Base.iszero(x::CustomNumber) = iszero(x.value)
 
         A = NDSparseArray{CustomNumber, 2}((2, 2))
         A[1, 1] = CustomNumber(5.0)