Add iswrapper test

Author: jishnub

test/runtests.jl

@@ -453,6 +453,7 @@ end
     end
     @testset "conversion and constantoperator" begin
         A = Conversion(PointSpace(1:4), PointSpace(1:4))
+        @test ApproxFunBase.iswrapper(A)
         @test convert(Number, A) == 1
         f = Fun(PointSpace(1:4))
         @test (A * A) * f == A * f == f