ClickHouse/tests/config/test_function.xml

<functions>
    <function>
        <type>executable</type>
        <name>test_function</name>
        <return_type>UInt64</return_type>
        <argument>
            <type>UInt64</type>
        </argument>
        <argument>
            <type>UInt64</type>
        </argument>
        <format>TabSeparated</format>
        <command>cd /; clickhouse-local --input-format TabSeparated --output-format TabSeparated --structure 'x UInt64, y UInt64' --query "SELECT x + y FROM table"</command>
        <execute_direct>0</execute_direct>
    </function>
</functions>