Test Any case, where fill! syntax required

[nickrobinson251]

I wondered why we use fill! in missings

Missings.jl/src/Missings.jl

Line 13 in 3ac53e9

missings(::Type{T}, dims::Dims) where {T} = fill!(Array{Union{T, Missing}}(undef, dims), missing)

and didn't just define it as Array{Union{T, Missing}}(undef, dims)

Turns out T = Any is the only case that definition wouldn't work for (AFAIK).
So this PR adds tests for that case :)

julia> Array{Union{Int, Missing}}(undef, (2, 3))
2×3 Array{Union{Missing, Int64},2}:
 missing  missing  missing
 missing  missing  missing

julia> struct F end

julia> Array{Union{F, Missing}}(undef, (2, 3))
2×3 Array{Union{Missing, F},2}:
 missing  missing  missing
 missing  missing  missing

julia> Array{Union{Any, Missing}}(undef, (2, 3))
2×3 Array{Any,2}:
 #undef  #undef  #undef
 #undef  #undef  #undef

[codecov-io]

Codecov Report

Merging #100 into master will increase coverage by 3.53%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           master   #100      +/-   ##
========================================
+ Coverage   88.46%    92%   +3.53%     
========================================
  Files           1      1              
  Lines          52     50       -2     
========================================
  Hits           46     46              
+ Misses          6      4       -2

Impacted Files	Coverage Δ
src/Missings.jl	92% <0%> (+3.53%)	⬆️

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[nalimilan]

Actually fill! is also needed for some Union types, where Missing isn't guaranteed to be the first type.

[nickrobinson251]

Actually fill! is also needed for some Union types, where Missing isn't guaranteed to be the first type.

Good to know! Thanks for clarifying :) At least we now have a test for one case where fill! is required