Test formatting of sf geometry columns

'sf' is one of the few packages that uses a list column in a data.frame
with a correctly working format() method. Since we disregard such
methods now, test that the correct behaviour still happens thanks to the
format() methods of the individual list items.

Author: aitap

inst/tests/other.Rraw

@@ -220,6 +220,7 @@ test(14.2, {example('CJ', package='data.table', local=TRUE, echo=FALSE); TRUE})
 if (loaded[["sf"]]) {  #2273
   DT = as.data.table(st_read(system.file("shape/nc.shp", package = "sf"), quiet=TRUE))
   test(15, DT[1:3, .(NAME, FIPS, geometry)], output="Ashe.*-81.4.*Surry.*-80.4")
+  test(15.1, DT, output="MULTIPOLYGON (((") # make sure individual list items are formatted, #6637, #5224
 
   dsf = sf::st_as_sf(data.table(x=1:10, y=1:10, s=sample(1:2, 10, TRUE)), coords=1:2)
   test(16, split(dsf, dsf$s), list(`1` = dsf[dsf$s == 1, ], `2` = dsf[dsf$s == 2, ]))