TestSuite.compare does not handle Nothing #272

 findfirst: Error During Test at /builds/JuliaGPU/CuArrays.jl/test/base.jl:313
  Test threw exception
  Expression: testf((x->begin
            findfirst(x)
        end), fill(false, 10))
  MethodError: no method matching length(::Nothing)
  Closest candidates are:
    length(!Matched::Core.SimpleVector) at essentials.jl:593
    length(!Matched::Base.MethodList) at reflection.jl:849
    length(!Matched::Core.MethodTable) at reflection.jl:923
    ...
  Stacktrace:
   [1] _similar_for(::UnitRange{Int64}, ::Type{Any}, ::Nothing, ::Base.HasLength) at ./array.jl:533
   [2] _collect(::UnitRange{Int64}, ::Nothing, ::Base.HasEltype, ::Base.HasLength) at ./array.jl:566
   [3] collect(::Nothing) at ./array.jl:560
   [4] #compare#1(::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}, ::typeof(Main.TestSuite.compare), ::Function, ::Type{CuArray}, ::Array{Bool,1}) at /builds/JuliaGPU/CuArrays.jl/.julia/packages/GPUArrays/OXvxB/test/testsuite.jl:24
   [5] compare at /builds/JuliaGPU/CuArrays.jl/.julia/packages/GPUArrays/OXvxB/test/testsuite.jl:20 [inlined]
   [6] #testf#3 at /builds/JuliaGPU/CuArrays.jl/test/runtests.jl:18 [inlined]
   [7] testf(::Function, ::Array{Bool,1}) at /builds/JuliaGPU/CuArrays.jl/test/runtests.jl:18
   [8] top-level scope at /builds/JuliaGPU/CuArrays.jl/test/base.jl:313
   [9] top-level scope at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.3/Test/src/Test.jl:1107
   [10] top-level scope at /builds/JuliaGPU/CuArrays.jl/test/base.jl:313