Bug: derive_vars_period fails when there is only one new var

[clarkliming]

What happened?

derive_vars_period fails when there are only one new_vars

Session Information

R version 4.3.3 (2024-02-29)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 22.04.4 LTS

Matrix products: default
BLAS:   /usr/lib/x86_64-linux-gnu/openblas-pthread/libblas.so.3 
LAPACK: /usr/lib/x86_64-linux-gnu/openblas-pthread/libopenblasp-r0.3.20.so;  LAPACK version 3.10.0

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

time zone: Etc/UTC
tzcode source: system (glibc)

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] admiral_1.1.1.9030 tidyr_1.3.0        testthat_3.2.0    

loaded via a namespace (and not attached):
 [1] htmlwidgets_1.6.4 devtools_2.4.5    remotes_2.5.0     processx_3.8.2   
 [5] callr_3.7.3       vctrs_0.6.4       tools_4.3.3       ps_1.7.5         
 [9] generics_0.1.3    tibble_3.2.1      fansi_1.0.5       pkgconfig_2.0.3  
[13] desc_1.4.2        lifecycle_1.0.3   compiler_4.3.3    stringr_1.5.0    
[17] brio_1.1.3        httpuv_1.6.15     htmltools_0.5.8.1 usethis_2.2.2    
[21] later_1.3.2       pillar_1.9.0      crayon_1.5.2      urlchecker_1.0.1 
[25] ellipsis_0.3.2    cachem_1.1.0      sessioninfo_1.2.2 mime_0.12        
[29] tidyselect_1.2.0  digest_0.6.33     stringi_1.7.12    dplyr_1.1.3      
[33] purrr_1.0.2       rprojroot_2.0.3   fastmap_1.2.0     cli_3.6.3        
[37] magrittr_2.0.3    pkgbuild_1.4.2    utf8_1.2.3        withr_2.5.1      
[41] admiraldev_1.1.0  diffdf_1.0.4      prettyunits_1.2.0 waldo_0.5.3      
[45] promises_1.3.0    lubridate_1.9.3   timechange_0.2.0  hms_1.1.3        
[49] memoise_2.0.1     shiny_1.9.1       evaluate_0.22     miniUI_0.1.1.1   
[53] profvis_0.3.8     rlang_1.1.1       Rcpp_1.0.11       xtable_1.8-4     
[57] glue_1.8.0        pkgload_1.3.3     rstudioapi_0.15.0 R6_2.5.1         
[61] fs_1.6.3     

Reproducible Example

expected <- tibble::tribble(
    ~USUBJID, ~AP01SDT,
    "1",      "2021-01-04",
    "2",      "2021-02-02",
  ) %>%
    mutate(
      across(matches("AP\\d\\d[ES]DT"), ymd)
    ) %>%
    mutate(
      STUDYID = "xyz"
    )

  period_ref <- tibble::tribble(
    ~USUBJID, ~APERIOD, ~APERSDT,     ~APEREDT,     ~APERSDTM,             ~APEREDTM,
    "1",             1, "2021-01-04", "2021-02-06", "2021-01-04 10:01:02", "2021-02-06 14:03:04",
    "2",             1, "2021-02-02", "2021-03-02", "2021-02-02 04:11:34", "2021-03-02 16:55:59"
  ) %>%
    mutate(
      STUDYID = "xyz",
      APERIOD = as.integer(APERIOD),
      APERSDT = ymd(APERSDT),
      APEREDT = ymd(APEREDT),
      APERSDTM = ymd_hms(APERSDTM),
      APEREDTM = ymd_hms(APEREDTM)
    )

  adsl <- tibble::tibble(STUDYID = "xyz", USUBJID = c("1", "2"))

derive_vars_period(
      adsl,
      dataset_ref = period_ref,
      new_vars = exprs(APxxSDT = APERSDT)
    )