patch 8.2.0418: code in eval.c not sufficiently covered by tests

Problem:    Code in eval.c not sufficiently covered by tests.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #5815)
diff --git a/src/testdir/test_method.vim b/src/testdir/test_method.vim
index 978e5f5..84d6c6c 100644
--- a/src/testdir/test_method.vim
+++ b/src/testdir/test_method.vim
@@ -35,6 +35,7 @@
   call assert_equal(v:t_list, l->type())
   call assert_equal([1, 2, 3], [1, 1, 2, 3, 3]->uniq())
   call assert_fails('eval l->values()', 'E715:')
+  call assert_fails('echo []->len', 'E107:')
 endfunc
 
 func Test_dict_method()
@@ -152,3 +153,5 @@
 func Test_method_not_supported()
   call assert_fails('eval 123->changenr()', 'E276:')
 endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab