R Under development (unstable) (2024-06-05 r86695 ucrt) -- "Unsuffered Consequences"
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> stopifnot(!any("package:nlme" == search())) # nlme *not* attached
> 
> ll <- LETTERS[1:10]
> subs <- rep(ll, rep(3,10))
> set.seed(101)# make reproducible
> resp <- rnorm(30)
> 
> ## 'nlme' not in search() :
> op <- options(warn = 2)  # there should be no (deprecation) warning
> (gd <- nlme::groupedData(resp ~ 1|subs))
Grouped Data: resp ~ 1 | subs
         resp subs
1  -0.3260365    A
2   0.5524619    A
3  -0.6749438    A
4   0.2143595    B
5   0.3107692    B
6   1.1739663    B
7   0.6187899    C
8  -0.1127343    C
9   0.9170283    C
10 -0.2232594    D
11  0.5264481    D
12 -0.7948444    D
13  1.4277555    E
14 -1.4668197    E
15 -0.2366834    E
16 -0.1933380    F
17 -0.8497547    F
18  0.0584655    F
19 -0.8176704    G
20 -2.0503078    G
21 -0.1637557    G
22  0.7085221    H
23 -0.2679805    H
24 -1.4639218    H
25  0.7444358    I
26 -1.4103902    I
27  0.4670676    I
28 -0.1193201    J
29  0.4672390    J
30  0.4981356    J
> options(op)
> ## failed in nlme < 3.1-129 (or previous to 2017-01-17)
> stopifnot(inherits(gd, "groupedData"),
+ 	  identical(dim(gd), c(30L, 2L)),
+ 	  inherits(gs <- gd[,"subs"], "ordered"),
+ 	  identical(sort(levels(gs)), ll),
+ 	  identical(sort.list(levels(gs)),
+ 		    c(5L, 9L, 8L, 4L, 10L, 2L, 1L, 6L, 7L, 3L)))
> 
> ## PR#18177 -- <groupedData>[j] should give a data frame
> require(nlme)
Loading required package: nlme
> stopifnot(is.data.frame(Meat[2]) # had 'drop=TRUE'
+ 	  , identical(Meat[,1, drop=FALSE], Meat[1])
+ 	  ) # gave vector in nlme < 3.1-153
> 
> proc.time()
   user  system elapsed 
   0.15    0.04    0.18