convert #6735 examples to tests

Author: MichaelChirico

inst/tests/tests.Rraw

@@ -20650,7 +20650,7 @@ test(2294.72,
                     label = list(character = "C3", VCharA = "Total", integer = 2L))),
      warning = "For the following variables, the 'label' value was already in the data: [VCharB (label: C3), VIntA (label: 2)]")
 
-# tests disabled -- fix for #4784 causes various breaking changes, e.g. #6735 and those below (2295.4+).
+# tests disabled -- fix for #4784 causes various breaking changes, at least partially covered by 2295.4+.
 # setDT no longer leaks class modification to origin copy, #4784
 # d1 = data.frame(a=1, row.names='b')
 # d2 = d1
@@ -20670,6 +20670,18 @@ e = new.env(parent=topenv())
 e$x = data.frame(a=1)
 foo('x', e)
 test(2295.5, is.data.table(e$x))
+# More regressions noted in #6735
+baz = function(x) setDT(x)
+foo = function(x) {
+  bar = function() baz(x)
+  x = data.frame(a=1)
+  bar()
+  is.data.table(x)
+}
+test(2295.6, foo())
+x = data.frame(a=1)
+baz(x)
+test(2295.7, is.data.table(x))
 
 # #6588: .checkTypos used to give arbitrary strings to stopf as the first argument
 test(2296, d2[x %no such operator% 1], error = '%no such operator%')