galaxy/test/functional/tools/expression_null_handling_boolean.xml

<tool name="expression_null_handling_boolean" id="expression_null_handling_boolean"
	  version="0.1.0" tool_type="expression">
    <expression type="ecma5.1">
        {return {'bool_out': $job.bool_input};}
    </expression>
    <inputs>
        <param type="boolean" label="Booelan input." name="bool_input" optional="true" />
    </inputs>
    <outputs>
        <output type="bool" name="bool_out" from="bool_out" />
    </outputs>
    <tests>
        <test>
            <param name="bool_input" value_json="true" />
            <output name="bool_out" value_json="true" />
        </test>
        <test>
            <param name="bool_input" value_json="false" />
            <output name="bool_out" value_json="false" />
        </test>
        <test>
            <param name="bool_input" value_json="null" />
            <output name="bool_out" value_json="null" />
        </test>
    </tests>
</tool>