more List.tree tests

S02-lists/tree.t

@@ -1,13 +1,20 @@
 use v6;
 use Test;
-plan 3;
+plan 8;
 
 is (1, 2, (3, 4)).tree.elems, 3, 'basic sanity (1)';
 is (1, 2, (3, 4)).tree.join('|'), '1|2|3 4', 'basic sanity (2)';
+ok List.tree === List, '.tree on a type object';
+is (1, 2, (3, 4)).tree(1).join('|'), '1|2|3 4', '.tree(1)';
+is (1, (2, (3, 4))).tree(1).[1].flat.elems, 3,
+    '.tree(1) really only goes one level deep';
 
+is (1, (2, (3, 4))).tree(2).[1].flat.elems, 2,
+    '.tree(2) goes two levels deep';
+is ~((1, 2), (3, 4)).tree(*.join('|')), '1|2 3|4',
+    'WhateverCode form, depth 1';
 
-#?rakudo skip 'Advanced forms of .tree'
-{
-    is ~((1, 2), (3, 4)).tree(*.join('|')), '1|2 3|4',
-       'WhateverCode form, depth 1';
-}
+
+#?rakudo skip 'multiple Whatever-closures'
+is (1, ((2, 3),  (4, 5))).tree(*.join('|'), *.join('+')).join('-'),
+    '1-2|3+4|5', '.tree with multiple Whatever-closures';