Pkg.installed() misdocumented or misbehave

[DANA-Laboratory]

Refer to this doc paragraph:

installed(pkg) → Void | VersionNumber

If pkg is installed, return the installed version number, otherwise return nothing.

and also this relate QA:

Pkg.installed("anInvalidPackage") function should return nothing but it throws an error:

julia> VERSION
v"0.5.0"
julia> Pkg.installed("anInvalidPackage")
ERROR: anInvalidPackage is not a package (not registered or installed)
 in installed(::String) at .\pkg\entry.jl:123
 in (::Base.Pkg.Dir.##2#3{Array{Any,1},Base.Pkg.Entry.#installed,Tuple{String}})
() at .\pkg\dir.jl:31
 in cd(::Base.Pkg.Dir.##2#3{Array{Any,1},Base.Pkg.Entry.#installed,Tuple{String}
}, ::String) at .\file.jl:48
 in #cd#1 at .\pkg\dir.jl:31
 in installed(::String) at .\pkg\pkg.jl:129

I think one of those, documentation or Pkg.installed() function behavior needs review.

[StefanKarpinski]

IIRC, this is intentional so this should be a doc fix:

• if the package is installed, return its version
• if the package exists but is not installed, return nothing
• if the package does not exist, raise an error.

[DANA-Laboratory]

same issue for Pkg.available()
related to:
#18206

[alexmorley]

Should be fixed by #19435 ?

[martinholters]

Yes.