server-tools/test_onchange_helper/demo/test_onchange_helper_message.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2019 ACSONE SA/NV
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl). -->

<odoo noupdate="1">

     <record id="message_demo_0_0" model="test_onchange_helper.message">
        <field name="discussion" ref="discussion_demo_0"/>
        <field name="body">Hey dude!</field>
    </record>

    <record id="message_demo_0_1" model="test_onchange_helper.message">
        <field name="discussion" ref="discussion_demo_0"/>
        <field name="author" ref="base.user_demo"/>
        <field name="body">What's up?</field>
    </record>

    <record id="message_demo_0_2" model="test_onchange_helper.message">
        <field name="discussion" ref="discussion_demo_0"/>
        <field name="body">This is a much longer message</field>
    </record>

</odoo>