patch 8.0.1209: still too many old style tests

Problem:    Still too many old style tests.
Solution:   Convert a few more tests to new style. (Yegappan Lakshmanan,
            closes #2230)

src/testdir/test_user_func.vim

@@ -0,0 +1,96 @@
+" Test for user functions.
+" Also test an <expr> mapping calling a function.
+" Also test that a builtin function cannot be replaced.
+" Also test for regression when calling arbitrary expression.
+
+func Table(title, ...)
+  let ret = a:title
+  let idx = 1
+  while idx <= a:0
+    exe "let ret = ret . a:" . idx
+    let idx = idx + 1
+  endwhile
+  return ret
+endfunc
+
+func Compute(n1, n2, divname)
+  if a:n2 == 0
+    return "fail"
+  endif
+  exe "let g:" . a:divname . " = ". a:n1 / a:n2
+  return "ok"
+endfunc
+
+func Expr1()
+  silent! normal! v
+  return "111"
+endfunc
+
+func Expr2()
+  call search('XX', 'b')
+  return "222"
+endfunc
+
+func ListItem()
+  let g:counter += 1
+  return g:counter . '. '
+endfunc
+
+func ListReset()
+  let g:counter = 0
+  return ''
+endfunc
+
+func FuncWithRef(a)
+  unlet g:FuncRef
+  return a:a
+endfunc
+
+func Test_user_func()
+  let g:FuncRef=function("FuncWithRef")
+  let g:counter = 0
+  inoremap <expr> ( ListItem()
+  inoremap <expr> [ ListReset()
+  imap <expr> + Expr1()
+  imap <expr> * Expr2()
+  let g:retval = "nop"
+
+  call assert_equal('xxx4asdf', Table("xxx", 4, "asdf"))
+  call assert_equal('fail', Compute(45, 0, "retval"))
+  call assert_equal('nop', g:retval)
+  call assert_equal('ok', Compute(45, 5, "retval"))
+  call assert_equal(9, g:retval)
+  call assert_equal(333, g:FuncRef(333))
+
+  enew
+
+  normal oXX+-XX
+  call assert_equal('XX111-XX', getline('.'))
+  normal o---*---
+  call assert_equal('---222---', getline('.'))
+  normal o(one
+  call assert_equal('1. one', getline('.'))
+  normal o(two
+  call assert_equal('2. two', getline('.'))
+  normal o[(one again
+  call assert_equal('1. one again', getline('.'))
+
+  call assert_equal(3, max([1, 2, 3]))
+  call assert_fails("call extend(g:, {'max': function('min')})", 'E704')
+  call assert_equal(3, max([1, 2, 3]))
+
+  " Regression: the first line below used to throw ?E110: Missing ')'?
+  " Second is here just to prove that this line is correct when not skipping
+  " rhs of &&.
+  call assert_equal(0, (0 && (function('tr'))(1, 2, 3)))
+  call assert_equal(1, (1 && (function('tr'))(1, 2, 3)))
+
+  delfunc Table
+  delfunc Compute
+  delfunc Expr1
+  delfunc Expr2
+  delfunc ListItem
+  delfunc ListReset
+  unlet g:retval g:counter
+  enew!
+endfunc