fix(testing): update getTestCaseNodes stub to match new signature

The getTestCaseNodes function was changed from a single-parameter
function returning an array to a 4-parameter function that mutates
the collection array in place (with additional visited and excludeSet
parameters for exclude support). Updated the test stub accordingly.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: andravin

src/test/testing/testController/workspaceTestAdapter.unit.test.ts

@@ -355,12 +355,14 @@ suite('Workspace test adapter', () => {
             );
             resultResolver.runIdToVSid.set('mockTestItem1', 'mockTestItem1');
 
-            sinon.stub(testItemUtilities, 'getTestCaseNodes').callsFake((testNode: TestItem) =>
-                // Custom implementation logic here based on the provided testNode and collection
-
-                // Example implementation: returning a predefined array of TestItem objects
-                [testNode],
-            );
+            sinon
+                .stub(testItemUtilities, 'getTestCaseNodes')
+                .callsFake((testNode: TestItem, collection: TestItem[] = []) => {
+                    // Custom implementation logic here based on the provided testNode and collection
+                    // Push the testNode to the collection (matching the real implementation behavior)
+                    collection.push(testNode);
+                    return collection;
+                });
 
             const mockTestItem1 = createMockTestItem('mockTestItem1');
             const mockTestItem2 = createMockTestItem('mockTestItem2');