test: add failing test for unresolvable path expression

Related to #87

Path FEEL expressions like `=agent.context` on an `Any`-typed variable
incorrectly resolve as `null` with `Null` type instead of `Any`.

Author: barinali

test/fixtures/zeebe/mappings/unresolvable-path-expression.bpmn

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<bpmn:definitions xmlns:bpmn="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:zeebe="http://camunda.org/schema/zeebe/1.0" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" xmlns:modeler="http://camunda.org/schema/modeler/1.0" id="Definitions_1" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="5.44.0" modeler:executionPlatform="Camunda Cloud" modeler:executionPlatformVersion="8.1.0">
+  <bpmn:process id="Process_1" isExecutable="true">
+    <bpmn:subProcess id="SubProcess_1" name="SubProcess_1">
+      <bpmn:extensionElements>
+        <zeebe:ioMapping>
+          <zeebe:input source="=agent.context" target="agentContext" />
+          <zeebe:output source="=agent" target="agent" />
+        </zeebe:ioMapping>
+      </bpmn:extensionElements>
+    </bpmn:subProcess>
+  </bpmn:process>
+  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
+    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Process_1">
+      <bpmndi:BPMNShape id="SubProcess_1_di" bpmnElement="SubProcess_1" isExpanded="true">
+        <dc:Bounds x="160" y="80" width="350" height="200" />
+        <bpmndi:BPMNLabel />
+      </bpmndi:BPMNShape>
+    </bpmndi:BPMNPlane>
+  </bpmndi:BPMNDiagram>
+</bpmn:definitions>

test/spec/zeebe/Mappings.spec.js

@@ -24,6 +24,7 @@ import propagationXML from 'test/fixtures/zeebe/mappings/propagation.bpmn';
 import scriptTaskXML from 'test/fixtures/zeebe/mappings/script-task.bpmn';
 import scriptTaskEmptyExpressionXML from 'test/fixtures/zeebe/mappings/script-task-empty-expression.bpmn';
 import scriptTaskOutputNoNameXML from 'test/fixtures/zeebe/mappings/script-task-output-no-name.bpmn';
+import unresolvablePathExpressionXML from 'test/fixtures/zeebe/mappings/unresolvable-path-expression.bpmn';
 
 import VariableProvider from 'lib/VariableProvider';
 
@@ -474,6 +475,38 @@ describe('ZeebeVariableResolver - Variable Mappings', function() {
   });
 
 
+  describe('Unresolvable path expression', function() {
+
+    beforeEach(bootstrap(unresolvablePathExpressionXML));
+
+
+    it('should resolve unresolvable path expression as <Any>', inject(async function(variableResolver, elementRegistry) {
+
+      // given
+      const subProcess = elementRegistry.get('SubProcess_1');
+
+      // when
+      const variables = await variableResolver.getVariablesForElement(subProcess);
+
+      // then
+      // cf. https://github.com/bpmn-io/variable-resolver/issues/87
+      expect(variables).to.variableEqual([
+        {
+          name: 'agentContext',
+          type: 'Any',
+          info: '=agent.context'
+        },
+        {
+          name: 'agent',
+          type: 'Any',
+          info: '=agent'
+        }
+      ]);
+    }));
+
+  });
+
+
   describe('Scope', function() {
 
     beforeEach(bootstrap(scopeXML));