Begin implementing null backend

[kescobo]

If you'd rather deal with this yourself, fine with me if you want to just close this. Closes #28

I'm not totally sure how to test this, since it would require getting the workflow runner to install the appropriate packages separately to make the other tests pass. But if you're ok with it, I think adding a disclaimer that this is untested would be ok 🤷

[cjdoris]

Thanks, be my guest :)

Off the top of my head, these API functions will need to change when backend is Null:

• envdir - throw an error, and document it can throw?
• withenv - already covered by activate!, but could also return f()
• which - just return Sys.which(progname)
• resolve - immediately return true
• gc - do nothing
• status - needs some logic to avoid checking+printing the currently installed versions

[kescobo]

• envdir - throw an error, and document it can throw?
• withenv - already covered by activate!, but could also return f()
  • The stuff before the try block isn't all that expensive - if it were me, I'd leave it to fall back to activate!(). But I put it in for now.
• which - just return Sys.which(progname)
• resolve - immediately return true
  • Other parts of this function return nothing, I just added the check to the first conditional block.
• gc - do nothing
• status - needs some logic to avoid checking+printing the currently installed versions

[kescobo]

Oops - didn't mean to close that 😆

[codecov]

Codecov Report

Merging #29 (192416c) into main (88248ae) will decrease coverage by 2.53%.
The diff coverage is 80.00%.

@@            Coverage Diff             @@
##             main      #29      +/-   ##
==========================================
- Coverage   93.32%   90.78%   -2.54%     
==========================================
  Files           7        7              
  Lines         584      597      +13     
==========================================
- Hits          545      542       -3     
- Misses         39       55      +16     

Impacted Files	Coverage Δ
src/backend.jl	41.66% <50.00%> (-41.67%)	⬇️
src/deps.jl	92.98% <100.00%> (+0.12%)	⬆️
src/env.jl	98.14% <100.00%> (+0.14%)	⬆️
src/resolve.jl	91.06% <100.00%> (ø)

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[cjdoris]

Looks good so far!

• Sure, I'm happy to put withenv back. The less special-casing the better.
• You're right about resolve, I was confusing it with something else.
• You added a message to status but there also needs some special casing to treat Null as always being resolved, but not actually displaying any installed versions. If you don't want to do that I'm happy to after the PR is merged.

It would be nice to test this, at least a bit. Maybe the tests could look at JULIA_CONDAPKG_BACKEND and modify the tests appropriately if it is Null?

[cjdoris]

On status, specifically it needs to set docurpkgs = resolved && backend() != :Null then replace resolved with docurpkgs in most places.

[kescobo]

On status, specifically it needs to set docurpkgs = resolved && backend() != :Null then replace resolved with docurpkgs in most places.

Here, I just have it return nothing up at the top after printing the message (that's what I originally intended, and just forgot 🤦 ). Is that OK?

[kescobo]

It would be nice to test this, at least a bit. Maybe the tests could look at JULIA_CONDAPKG_BACKEND and modify the tests appropriately if it is Null?

Working on this now

[kescobo]

Not sure if there's a more elegant way to do this, maybe using ReTest.jl or something. But this works.

Can test locally by doing:

julia> using Pkg

julia> withenv("JULIA_CONDAPKG_BACKEND"=> "Null") do
           Pkg.test()
       end

[cjdoris]

Looks great, all your comments are fine.

Boldly merging even though there are 2 tests still running.

Thanks very much for your contribution.

[kescobo]

You're welcome! Thanks for quick review and help :-)