tests/lapi: fix string_rep_test

The patch fixes description (synopsis is at the end of the
description) and fixes lower boundary for `n`, with `n` equal
to zero assertion calculates negative number in right part of
expression.

Author: ligurio

tests/lapi/string_rep_test.lua

@@ -5,10 +5,10 @@ Copyright (c) 2023-2025, Sergey Bronnikov.
 6.4 – String Manipulation
 https://www.lua.org/manual/5.3/manual.html#6.4
 
-Synopsis: string.rep(s, n [, sep])
-
 read overflow in 'l_strcmp',
 https://github.com/lua/lua/commit/f623b969325be736297bc1dff48e763c08778243
+
+Synopsis: string.rep(s, n [, sep])
 ]]
 
 local luzer = require("luzer")
@@ -18,7 +18,7 @@ local function TestOneInput(buf, _size)
     local fdp = luzer.FuzzedDataProvider(buf)
     os.setlocale(test_lib.random_locale(fdp), "all")
     -- Huge length leads to slow units.
-    local n = fdp:consume_integer(0, test_lib.MAX_STR_LEN)
+    local n = fdp:consume_integer(1, test_lib.MAX_STR_LEN)
     local s = fdp:consume_string(test_lib.MAX_STR_LEN)
     local sep = fdp:consume_string(test_lib.MAX_STR_LEN)
     local len = string.len(string.rep(s, n, sep))