add warnings about skipped objects

Author: m7pr

R/qenv-extract.R

@@ -18,16 +18,27 @@
 #' @export
 `[.qenv` <- function(x, names) {
   checkmate::assert_class(names, "character")
-  names_in_env <- intersect(names, ls(get_env(x)))
-  if (!length(names_in_env)) {
+  possible_names <- ls(get_env(x))
+  names_warn <- setdiff(names, possible_names)
+  names <- intersect(names, possible_names)
+  if (!length(names)) {
     warning("None of `names` elements exist in `qenv`. Returning empty `qenv`.")
     return(qenv())
   }
 
-  limited_code <- get_code(x, names = names_in_env)
+  if (length(names_warn)) {
+    warning(
+      sprintf(
+        "Some elements of `names` do not exist in `qenv`. Skipping those: %s.",
+        paste(names_warn, collapse = ", ")
+      )
+    )
+  }
+
+  limited_code <- get_code(x, names = names)
   indexes <- which(x@code %in% limited_code)
 
-  x@env <- list2env(mget(x = names_in_env, envir = get_env(x)))
+  x@env <- list2env(mget(x = names, envir = get_env(x)))
   x@code <- limited_code
   x@id <- x@id[indexes]
   x@warnings <- x@warnings[indexes]

tests/testthat/test-qenv_extract.R

@@ -1,3 +1,19 @@
+testthat::test_that("`[.` returns empty qenv for names not in qenv", {
+  data <- within(qenv(), {x = 1; a = 2})
+  testthat::expect_warning(
+    testthat::expect_equal(data["y"], qenv()),
+    "None of `names` elements exist in `qenv`. Returning empty `qenv`."
+  )
+})
+
+testthat::test_that("`[.` returns limited qenv for some names not in qenv", {
+  data <- within(qenv(), {x = 1; a = 2})
+  testthat::expect_warning(
+    testthat::expect_equal(data[c("y", "a")], data["a"]),
+    "Some elements of `names` do not exist in `qenv`. Skipping those: y."
+  )
+})
+
 testthat::test_that("`[.` extracts proper objects", {
   q <- qenv()
   code <- c("x<-1", "a<-1;b<-2")