feat: Add a unit test target (jest) to the UI extension and run it in CI (#1192)

- Introduce test targets.
- Adding additional tests.

Related to: https://github.com/harvester/harvester/issues/11892

Signed-off-by: Volker Theile <vtheile@suse.com>

pkg/harvester/models/__tests__/kubevirt.io.virtualmachineinstance.test.js

@@ -0,0 +1,57 @@
+import { reactive } from 'vue';
+import VirtVmInstance from '../kubevirt.io.virtualmachineinstance';
+import { HCI } from '../../types';
+import { HCI as HCI_ANNOTATIONS } from '../../config/labels-annotations';
+
+jest.mock('../harvester', () => ({ __esModule: true, default: class {} }));
+jest.mock('@shell/plugins/dashboard-store/resource-class', () => ({ colorForState: () => 'text-info' }));
+
+function migration(namespace, timestamp, phase = 'Running') {
+  return {
+    metadata: { namespace, creationTimestamp: timestamp },
+    spec:     { vmiName: 'vm1' },
+    status:   { phase },
+  };
+}
+
+function createVmi(migrations) {
+  const list = reactive(migrations);
+  const vmi = Object.create(VirtVmInstance.prototype);
+
+  Object.assign(vmi, {
+    metadata: {
+      namespace:   'ns1',
+      name:        'vm1',
+      annotations: { [HCI_ANNOTATIONS.MIGRATION_STATE]: 'Migrating' },
+    },
+    $getters:     { all: (type) => type === HCI.VMIM ? list : [] },
+    $rootGetters: { 'harvester/all': (type) => type === HCI.VMIM ? list : [] },
+  });
+
+  return { vmi, list };
+}
+
+describe('class VirtVmInstance', () => {
+  it('should follow additions, timestamp changes, phase changes and removals in the same list', () => {
+    const { vmi, list } = createVmi([]);
+
+    expect(vmi.vmimResource).toStrictEqual([]);
+    expect(vmi.migrationState).toBeNull();
+
+    list.push(migration('ns1', '2026-01-01T00:00:00Z'));
+    expect(vmi.migrationState.status).toBe('Migrating');
+
+    list.push(migration('ns1', '2026-01-02T00:00:00Z', 'Failed'));
+    expect(vmi.migrationState.status).toBe('Failed');
+
+    list[0].metadata.creationTimestamp = '2026-01-03T00:00:00Z';
+    expect(vmi.vmimResource).toBe(list[0]);
+    expect(vmi.migrationState.status).toBe('Migrating');
+
+    list[0].status.phase = 'Failed';
+    expect(vmi.migrationState.status).toBe('Failed');
+
+    list.splice(0, 2);
+    expect(vmi.migrationState).toBeNull();
+  });
+});