add test for as.data.table.list conversion

Author: ben-schwen

R/as.data.table.R

@@ -130,10 +130,6 @@ as.data.table.list = function(x,
                 # e.g. cbind(foo=DF1, bar=DF2) have .named=c(TRUE,TRUE) due to the foo= and bar= and trigger "prefix." for non-vector items
   ...)
 {
-  if (is.data.table(x)) {
-    # operate on plain list to avoid [[<-.data.table dispatch
-    x = as.list(x)
-  }
   n = length(x)
   eachnrow = integer(n)          # vector of lengths of each column. may not be equal if silent repetition is required.
   eachncol = integer(n)
@@ -145,6 +141,12 @@ as.data.table.list = function(x,
   rownames_ = NULL
   check_rownames = !isFALSE(keep.rownames)
 
+  # conversion must happen after capturing names
+  if (is.data.table(x)) {
+    # operate on plain list to avoid [[<-.data.table dispatch
+    x = as.list(x)
+  }
+
   for (i in seq_len(n)) {
     xi = x[[i]]
     if (is.null(xi)) next    # eachncol already initialized to 0 by integer() above

inst/tests/tests.Rraw

@@ -4094,6 +4094,8 @@ test(1140, as.data.table(X), data.table(a=c(1:2,1L), b=c(1:3)),
 test(1141.1, data.table(a=1:2, b=1:3), data.table(a=c(1L,2L,1L), b=1:3),                                              warning="Item 1 has 2 rows but longest item has 3; recycled")
 test(1141.2, data.table(a=1:2, data.table(x=1:5, y=6:10)), data.table(a=c(1L,2L,1L,2L,1L), x=1:5, y=6:10),            warning="Item 1 has 2 rows but longest item has 5; recycled")
 test(1141.3, data.table(a=1:5, data.table(x=c(1,2), y=c(3,4))), data.table(a=c(1:5), x=c(1,2,1,2,1), y=c(3,4,3,4,3)), warning="Item 2 has 2 rows but longest item has 5; recycled")
+x = structure(list(1, 2), class = c("list", "data.table"))
+test(1141.4, as.data.table(x), data.table(V1=c(1), V2=c(2)))
 
 # Fix for bug #79 - DT[, foo()] returns function definition.
 DT <- data.table(a=1:2)