using Test
using IntervalArithmetic

@testset "widened interval is superset" begin
    a = unit_ball(Float64)
    @test a ⊂ widened(a)
    @test !(widened(a) ⊂ widened(a))
    @test a ⪽ widened(a)
    @test !(widened(a) ⪽ widened(a))
    @test a ⊆ widened(a)
    @test widened(a) ⊆ widened(a)
end

@testset "sign in unit ball" begin
    a = unit_ball(Float64)
    b = nonnegatives(Float64)
    c = interval(2)
    @test sign(c) ⊆ a
    @test sign(-c) ⊆ a
    @test sign(b) ⊆ a
    @test sign(a) ⊆ a
end
