patch 9.1.0415: Some functions are not tested

Problem:  Some functions are not tested
Solution: Add a few more tests, fix a few minor problems
          (Yegappan Lakshmanan)

closes: #14789

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_method.vim b/src/testdir/test_method.vim
index 120fade..f18ac14 100644
--- a/src/testdir/test_method.vim
+++ b/src/testdir/test_method.vim
@@ -136,6 +136,13 @@
   call assert_fails('eval [1, 2, 3] ->sort ()', 'E274:')
   call assert_fails('eval [1, 2, 3]-> sort ()', 'E274:')
   call assert_fails('eval [1, 2, 3]-> sort()', 'E274:')
+
+  " Test for using a method name containing a curly brace name
+  let s = 'len'
+  call assert_equal(4, "xxxx"->str{s}())
+
+  " Test for using a method in an interpolated string
+  call assert_equal('4', $'{"xxxx"->strlen()}')
 endfunc
 
 func Test_method_lambda()