Missing numbers tests (#34448)

Author: bramtayl

test/numbers.jl

@@ -2342,6 +2342,15 @@ for (d,B) in ((4//2+1im,Rational{BigInt}),(3.0+1im,BigFloat),(2+1im,BigInt))
     @test big.([d]) == [d]
 end
 
+# big fallback
+import Base: zero, big
+struct TestNumber{Inner} <: Number
+    inner::Inner
+end
+zero(::Type{TestNumber{Inner}}) where {Inner} = TestNumber(zero(Inner))
+big(test_number::TestNumber) = TestNumber(big(test_number.inner))
+@test big(TestNumber{Int}) == TestNumber{BigInt}
+
 @testset "multiplicative inverses" begin
     function testmi(numrange, denrange)
         for d in denrange
@@ -2371,6 +2380,7 @@ end
     @test !isinteger(π)
     @test size(1) == ()
     @test length(1) == 1
+    @test firstindex(1) == 1
     @test lastindex(1) == 1
     @test eltype(Integer) == Integer
 end