oneunit of unitfull matrix should return a unitfull matrix (#30227)

Author: KlausC

base/array.jl

@@ -460,7 +460,7 @@ function _one(unit::T, x::AbstractMatrix) where T
     # Matrix{T}(I, m, m)
     I = zeros(T, m, m)
     for i in 1:m
-        I[i,i] = 1
+        I[i,i] = unit
     end
     I
 end

stdlib/SparseArrays/test/sparse.jl

@@ -2335,7 +2335,6 @@ end
     @test m2.module == SparseArrays
 end
 
-
 @testset "sprandn with type $T" for T in (Float64, Float32, Float16, ComplexF64, ComplexF32, ComplexF16)
     @test sprandn(T, 5, 5, 0.5) isa AbstractSparseMatrix{T}
 end

test/arrayops.jl

@@ -6,6 +6,7 @@ using .Main.OffsetArrays
 using SparseArrays
 
 using Random, LinearAlgebra
+using Dates
 
 @testset "basics" begin
     @test length([1, 2, 3]) == 3
@@ -2577,3 +2578,7 @@ Base.view(::T25958, args...) = args
     @test t[end,end,1]   == @view(t[end,end,1])   == @views t[end,end,1]
     @test t[end,end,end] == @view(t[end,end,end]) == @views t[end,end,end]
 end
+
+# Fix oneunit bug for unitful arrays
+@test oneunit([Second(1) Second(2); Second(3) Second(4)]) == [Second(1) Second(0); Second(0) Second(1)]
+