Set metadata in packrat lockfile

[cderv]

Hey,

This is related #425. @kevinushey I followed you advice and made one function to change different metadata. Just two for the moment repos and r_version. I think the others are not useful to modify.

Can you take a look and tell me if the direction I took is ok ?

I tried to write some tests but I don't manage to make them work. It seems like other test are not working either.
I tried something like that

projRoot <- cloneTestProject("healthy")
  init(enter = FALSE, projRoot, options = list(local.repos = "packages"))

but init does not work as expected.
help appreciated for those tests. thanks.

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This change is 

[kevinushey]

Most of the Packrat APIs take the project as the first argument -- can we follow that convention here?

[cderv]

I followed the convention of set_opts and get_opts that I find close in functionality. project is last in get_opts and second in set_opts. From usage :

get_opts(options = NULL, simplify = TRUE, project = NULL)
set_opts(..., project = NULL, persist = TRUE)

bad idea ?
Still want me to change ?

[kevinushey]

Good point! I think you're right; let's leave it as is then.

[kevinushey]

Can we use FALSE instead of the abbreviated F here?

[cderv]

Absolutely right ! Good practice still not automatic for me. Done!

[kevinushey]

Thanks!

[cderv]

Oh thanks for merging!
I thought it needed a test file but as I did not manage to make it work I did not push it. If you want me to still try for later do not hesitate to tell me!
Should we add a bullet to NEWS.md too ?
I also closed manually the related issue. Forgot to add closing keyword in the PR or commit message.

thanks again for you review !

[kevinushey]

I added a NEWS bullet and bumped the version here:

6ff1185

I'd welcome a PR adding tests as well if you have the time to put something together as well. Thanks for taking the time to put this together!

[cderv]

Thanks, should have looked in the other commit..
For the test, I tried to get inspiration from other tests but they are skipped on cran and does not seem to work anymore. I did not manage to created a dummy packrat project in temp folder.i will keep trying and I will come up with something eventually. You will welcome a PR when it is ready. No rush but will be better if tested.