diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 5249d4e..6f65ae0 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -872,7 +872,7 @@
 
   set fileformat=mac
   call assert_equal([-1, -1, 1, 1, 2, 2, 2, 3, 3, -1],
-  \                 map(range(-1, 8), 'byte2line(v:val)'))
+  \                 map(range(-1, 8), 'v:val->byte2line()'))
   call assert_equal([-1, -1, 1, 3, 6, 8, -1],
   \                 map(range(-1, 5), 'line2byte(v:val)'))
 
@@ -895,6 +895,34 @@
   bw!
 endfunc
 
+func Test_byteidx()
+  let a = '.é.' " one char of two bytes
+  call assert_equal(0, byteidx(a, 0))
+  call assert_equal(0, byteidxcomp(a, 0))
+  call assert_equal(1, byteidx(a, 1))
+  call assert_equal(1, byteidxcomp(a, 1))
+  call assert_equal(3, byteidx(a, 2))
+  call assert_equal(3, byteidxcomp(a, 2))
+  call assert_equal(4, byteidx(a, 3))
+  call assert_equal(4, byteidxcomp(a, 3))
+  call assert_equal(-1, byteidx(a, 4))
+  call assert_equal(-1, byteidxcomp(a, 4))
+
+  let b = '.é.' " normal e with composing char
+  call assert_equal(0, b->byteidx(0))
+  call assert_equal(1, b->byteidx(1))
+  call assert_equal(4, b->byteidx(2))
+  call assert_equal(5, b->byteidx(3))
+  call assert_equal(-1, b->byteidx(4))
+
+  call assert_equal(0, b->byteidxcomp(0))
+  call assert_equal(1, b->byteidxcomp(1))
+  call assert_equal(2, b->byteidxcomp(2))
+  call assert_equal(4, b->byteidxcomp(3))
+  call assert_equal(5, b->byteidxcomp(4))
+  call assert_equal(-1, b->byteidxcomp(5))
+endfunc
+
 func Test_count()
   let l = ['a', 'a', 'A', 'b']
   call assert_equal(2, count(l, 'a'))
@@ -1506,6 +1534,7 @@
 
 func Test_call()
   call assert_equal(3, call('len', [123]))
+  call assert_equal(3, 'len'->call([123]))
   call assert_fails("call call('len', 123)", 'E714:')
   call assert_equal(0, call('', []))
 
@@ -1513,6 +1542,7 @@
      return len(self.data)
   endfunction
   let mydict = {'data': [0, 1, 2, 3], 'len': function("Mylen")}
+  eval mydict.len->call([], mydict)->assert_equal(4)
   call assert_fails("call call('Mylen', [], 0)", 'E715:')
 endfunc