test/win: fix some environment assumptions #7912

fix #7909
fix #7910

test/functional/eval/hostname_spec.lua

@@ -1,7 +1,9 @@
 local helpers = require('test.functional.helpers')(after_each)
+local eq = helpers.eq
 local ok = helpers.ok
 local call = helpers.call
 local clear = helpers.clear
+local iswin = helpers.iswin
 
 describe('hostname()', function()
   before_each(clear)
@@ -11,7 +13,8 @@ describe('hostname()', function()
     ok(string.len(actual) > 0)
     if call('executable', 'hostname') == 1 then
       local expected = string.gsub(call('system', 'hostname'), '[\n\r]', '')
-      helpers.eq(expected, actual)
+      eq((iswin() and expected:upper() or expected),
+         (iswin() and actual:upper() or actual))
     end
   end)
 end)