WIP: Tests for Base.cwstring

[rileysheridan]

I made simple unit tests for this function, but I would like some clarification on empty string and NUL terminated string inputs. cwstring currently throws an error for both, but I test for valid return vectors. If that's wrong, I can change the first and third tests.

Also, sorry for the wall of filemode changes. I tried to remove them from the commit but kept getting "unable to index file" errors. Advice on how to fix would be appreciated!

[giordano]

Also, sorry for the wall of filemode changes. I tried to remove them from the commit but kept getting "unable to index file" errors. Advice on how to fix would be appreciated!

What operating system are you using? How are you interacting with git? The command line interface/VS Code/something else?

[giordano]

Base.cwstring is only defined on Windows:

julia/base/strings/cstring.jl

Lines 108 to 124 in b0c1525

	if ccall(:jl_get_UNAME, Any, ()) === :NT
	"""
	Base.cwstring(s)
	Converts a string `s` to a NUL-terminated `Vector{Cwchar_t}`, suitable for passing to C
	functions expecting a `Ptr{Cwchar_t}`. The main advantage of using this over the implicit
	conversion provided by [`Cwstring`](@ref) is if the function is called multiple times with the
	same argument.
	This is only available on Windows.
	"""
	function cwstring(s::AbstractString)
	bytes = codeunits(String(s))
	0 in bytes && throw(ArgumentError("embedded NULs are not allowed in C strings: $(repr(s))"))
	return push!(transcode(UInt16, bytes), 0)
	end
	end

This testset should only be run on Windows, otherwise it'll fail on other platforms, which means you should change this to

if Sys.iswindows()
    @testset "cwstring" begin
        # ...
    end
end