Decision Engine: Handling Question mark Operator in decision table unary test expressions

[ChinchuAjith]

DMN TCK Tests - Few test cases from 1157-unarytests-decisiontable-test-01.xml Fails.

1157-unarytests-decisiontable-test-01.xml

1157-unarytests-decisiontable.txt

This ticket focuses on identifying the root cause of errors introduced by PR dmn-tck/tck#672. Below are the failing tests case introduced by this PR.

<testCase id="006">
    <description>input values: input expression is valid against input values - '?' symbol with built-in function</description>
    <!-- also shows input values unary tests can call built-in functions -->
    <resultNode name="decision006" type="decision">
        <expected>
            <value xsi:type="xsd:string">success</value>
        </expected>
    </resultNode>
</testCase>

<testCase id="006_a">
    <description>input values: input expression is valid against input values - '?' inside literal string</description>
    <resultNode name="decision006_a" type="decision">
        <expected>
            <value xsi:type="xsd:string">success</value>
        </expected>
    </resultNode>
</testCase>

<testCase id="006_c">
    <description>input values: "?" symbol alone will be satisfied a true value</description>
    <resultNode name="decision006_c" type="decision">
        <expected>
            <value xsi:type="xsd:string">success</value>
        </expected>
    </resultNode>
</testCase>

<testCase id="008_b">
    <!-- further to 008, an input expression of boolean "false" will not be satisfied against a rule
     unary test of that evaluates to true -->
    <description>input values: boolean expression is weird</description>
    <resultNode name="decision008_b" type="decision">
        <expected>
            <value xsi:type="xsd:string">success</value>
        </expected>
    </resultNode>
</testCase>

<testCase id="015">
    <description>output values: ? used in tests - satisfied</description>
    <resultNode name="decision015" type="decision">
        <expected>
            <value xsi:type="xsd:string">foo</value>
        </expected>
    </resultNode>
</testCase>

ERROR: FAILURE: 'decision006' expected='success' but found='null'
ERROR: FAILURE: 'decision006_a' expected='success' but found='null'
ERROR: FAILURE: 'decision006_c' expected='success' but found='null'
ERROR: FAILURE: 'decision008_b' expected='success' but found='null'
ERROR: FAILURE: 'decision015' expected='foo' but found='null'