feat(2606): added tests for list_search on tables changes

Author: manmita

NEWS.md

@@ -16,6 +16,8 @@
 
 1. `nafill()`, `setnafill()` extended to work on logical vectors (part of [#3992](https://github.com/Rdatatable/data.table/issues/3992)). Thanks @jangorecki for the request and @MichaelChirico for the PR.
 
+2. `tables()` can now optionally report `data.table` objects stored one level deep inside list objects when `list_search=TRUE`, with `list_len_threshold` to avoid scanning extremely long lists, [#2606](https://github.com/Rdatatable/data.table/issues/2606).
+
 ### Notes
 
 1. {data.table} now depends on R 3.5.0 (2018).

inst/tests/tests.Rraw

@@ -21978,3 +21978,19 @@ local({
   test(2357.1, fread(f), DT)
   test(2357.2, fread(paste0("file://", f)), DT)
 })
+
+#2606 tables() list_search finds nested data.tables in lists
+xenv2 = new.env()
+xenv2$L = list(
+  data.table(a = 1L),
+  data.table(a = 1:2)
+)
+test(2358.1,
+  tables(env = xenv2, silent = TRUE, list_search = TRUE)[, .(NAME, NROW, NCOL)],
+  data.table(NAME = c("L[[1]]", "L[[2]]"), NROW = c(1L, 2L), NCOL = c(1L, 1L))
+)
+test(2358.2,
+  nrow(tables(env = xenv2, silent = TRUE, list_search = TRUE, list_len_threshold = 1L)),
+  0L
+)
+rm(xenv2)