Hi!
I'm absolutely new to renv, and started to use today for the first time. Based on the Introduction to renv vignette, it seemed to be a viable alternative to conda by creating isolated virtul environments, but it's doesn't seem to be doing what I expected it to do.
Setup
I created a new RStudio project, and chose to use renv with it.
Inital contents of renv.lock
{
  "R": {
    "Version": "4.1.0",
    "Repositories": [
      {
        "Name": "CRAN",
        "URL": "https://cran.rstudio.com"
      }
    ]
  },
  "Packages": {
    "renv": {
      "Package": "renv",
      "Version": "0.13.2",
      "Source": "Repository",
      "Repository": "CRAN",
      "Hash": "079cb1f03ff972b30401ed05623cbe92"
    }
  }
}
Then I installed the fpp3 package, and I was able to load it successfully.
> library(fpp3)
-- Attaching packages ------------------------------------------------ fpp3 0.4.0 --
v tibble      3.1.2      v tsibble     1.0.1 
v dplyr       1.0.6      v tsibbledata 0.3.0 
v tidyr       1.1.3      v feasts      0.2.2 
v lubridate   1.7.10     v fable       0.3.1 
v ggplot2     3.3.3      
-- Conflicts ----------------------------------------------------- fpp3_conflicts --
x lubridate::date()    masks base::date()
x dplyr::filter()      masks stats::filter()
x tsibble::intersect() masks base::intersect()
x tsibble::interval()  masks lubridate::interval()
x dplyr::lag()         masks stats::lag()
x tsibble::setdiff()   masks base::setdiff()
x tsibble::union()     masks base::union()
Problem
I wanted a snapshot of this state, so tried for that, but renv didn't allow it.
> renv::snapshot()
* The lockfile is already up to date.
And the renv.lock file contents remained unchanged.
I considered the possibility that something is captured "somehow", and uninstalled fpp3. Then if I called to restore it, obviously it did not, saying it's already up to date.
> .libPaths()
[1] "C:/Users/anirb/Desktop/fpp3/renv/library/R-4.1/x86_64-w64-mingw32"
[2] "C:/Users/anirb/AppData/Local/Temp/Rtmpao4McL/renv-system-library" 
> utils::remove.packages("fpp3")
Removing package from ‘C:/Users/anirb/Desktop/fpp3/renv/library/R-4.1/x86_64-w64-mingw32’
(as ‘lib’ is unspecified)
> library(fpp3)
Error in library(fpp3) : there is no package called ‘fpp3’
> renv::restore()
* The library is already synchronized with the lockfile.
Question
Is this behaviour expected? If so, can someone please explain what is the point of using renv if I can't take a snapshot when I choose to do it? If not, what can I do to fix this?
Session Info
> sessionInfo()
R version 4.1.0 (2021-05-18)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 19043)
Matrix products: default
locale:
[1] LC_COLLATE=English_India.1252  LC_CTYPE=English_India.1252   
[3] LC_MONETARY=English_India.1252 LC_NUMERIC=C                  
[5] LC_TIME=English_India.1252    
attached base packages:
[1] stats     graphics  grDevices datasets  utils     methods   base     
loaded via a namespace (and not attached):
[1] compiler_4.1.0 tools_4.1.0    renv_0.13.2
Thanks.