web/web_widget_char_switchcase/views/web_widget_char_switchcase.xml

<?xml version="1.0" encoding="utf-8"?>

<odoo>
    <template id="web_widget_char_switchcase_assets" name="Switchcase widget" inherit_id="web.assets_backend">
        <xpath expr="." position="inside">
            <script type="text/javascript" src="/web_widget_char_switchcase/static/src/js/web_widget_char_switchcase.js"/>
        </xpath>
    </template>

    <template id="qunit_suite" inherit_id="web.qunit_suite">
        <xpath expr="//t[@t-set='head']" position="inside">
            <script type="text/javascript" src="/web_widget_char_switchcase/static/test/web_widget_char_switchcase.js"/>
        </xpath>
    </template>
</odoo>