DMN TCK PRPOSAL - Improve Test Result Context Representation

DMN_TCK_IMPROVE_CONTEXT_REPRESENTATION.md

Proposal: Improve Test Result Context Representation

It's currently harder than it should be to interpret the test results in the DMN TCK.

Context

The following expected test result

<expected>
  <component name="a">
      <value xsi:type="xsd:decimal">2</value>
  </component>
</expected>

...maps to a FEEL context data structure with one entry:

{ a: 2 }

Adding another entry, the result looks like this:

<expected>
  <component name="a">
      <value xsi:type="xsd:decimal">2</value>
  </component>
  <component name="b">
      <value xsi:type="xsd:decimal">2</value>
  </component>
</expected>

The required FEEL data structure is a context again, containing two entries with a and b as keys:

{ a: 2, b: 2 }

Problem

Two issues make it hard to understand such test results:

• Context boundaries are not spawned explicitly
• Result names are not aligned with feel naming

Proposed Improvement

Describe context explicitly using FEEL terminology:

<expected>
  <context>
    <entry name="a">
        <value xsi:type="xsd:decimal">2</value>
    </entry>
  </context>
</expected>

Embedded into a list:

<expected>
  <list>
    <item>
      <context>
        <entry name="a">
            <value xsi:type="xsd:decimal">2</value>
        </entry>
      </context>
    </item>
  </list>
</expected>

With multiple entries and context nesting:

<expected>
  <context>
    <entry name="a">
        <value xsi:type="xsd:decimal">2</value>
    </entry>
    <entry name="b">
      <context>
        <entry name="foo">
            <value xsi:type="xsd:string">BAR</value>
        </entry>
      </context>
    </entry>
  </context>
</expected>

Alternatives

A partial alternative for FEEL tests is to make these available standalone:

for item in [1, 2, 3][> 2] return concat("item-", string(item)) = [ "item-3" ]
1 + 6 * 3 = 19

For each of these entries, for a FEEL interpreter to pass the test:

engine.evalutateExpression(expression) === true