vim-patch:9.1.0419: eval.c not sufficiently tested

Problem:  eval.c not sufficiently tested
Solution: Add a few more additional tests for eval.c,
          (Yegappan Lakshmanan)

closes: vim/vim#14799

4776e64e72

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

test/old/testdir/test_autoload.vim

@@ -21,5 +21,4 @@ func Test_source_autoload()
   call assert_equal(1, g:loaded_sourced_vim)
 endfunc
 
-
 " vim: shiftwidth=2 sts=2 expandtab

test/old/testdir/test_fold.vim

@@ -1497,6 +1497,35 @@ func Test_foldtext_in_modeline()
   delfunc ModelineFoldText
 endfunc
 
+" Test for setting 'foldexpr' from the modeline and executing the expression
+" in a sandbox
+func Test_foldexpr_in_modeline()
+  func ModelineFoldExpr()
+    call feedkeys('aFoo', 'xt')
+    return strlen(matchstr(getline(v:lnum),'^\s*'))
+  endfunc
+  let lines =<< trim END
+    aaa
+     bbb
+      ccc
+      ccc
+     bbb
+    aaa
+    " vim: foldenable foldmethod=expr foldexpr=ModelineFoldExpr()
+  END
+  call writefile(lines, 'Xmodelinefoldexpr', 'D')
+
+  set modeline modelineexpr
+  split Xmodelinefoldexpr
+
+  call assert_equal(2, foldlevel(3))
+  call assert_equal(lines, getbufline('', 1, '$'))
+
+  bw!
+  set modeline& modelineexpr&
+  delfunc ModelineFoldExpr
+endfunc
+
 " Make sure a fold containing a nested fold is split correctly when using
 " foldmethod=indent
 func Test_fold_split()

test/old/testdir/test_substitute.vim

@@ -1507,4 +1507,18 @@ func Test_substitute_expr_recursive()
   exe bufnr .. "bw!"
 endfunc
 
+" Test for changing 'cpo' in a substitute expression
+func Test_substitute_expr_cpo()
+  func XSubExpr()
+    set cpo=
+    return 'x'
+  endfunc
+
+  let save_cpo = &cpo
+  call assert_equal('xxx', substitute('abc', '.', '\=XSubExpr()', 'g'))
+  call assert_equal(save_cpo, &cpo)
+
+  delfunc XSubExpr
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

test/old/testdir/test_vimscript.vim

@@ -7450,12 +7450,13 @@ func Test_for_over_string()
   endfor
   call assert_equal('', res)
 
-  " Test for ignoring loop var assignment
-  let c = 0
-  for _ in 'abc'
-    let c += 1
+  " Test for using "_" as the loop variable
+  let i = 0
+  let s = 'abc'
+  for _ in s
+    call assert_equal(s[i], _)
+    let i += 1
   endfor
-  call assert_equal(3, c)
 endfunc
 
 " Test for deeply nested :source command  {{{1