test: add maintenance-worker-factory unit tests (#606)

Co-authored-by: Ricardo Cabral <me@ricardocabral.io>

Author: phoenix-server

.changeset/test-maintenance-worker-factory.md

@@ -0,0 +1,5 @@
+---
+"nostream": patch
+---
+
+Add unit tests for maintenance-worker-factory with 100% code coverage

test/unit/factories/maintenance-worker-factory.spec.ts

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+import { expect } from 'chai'
+
+import { MaintenanceWorker } from '../../../src/app/maintenance-worker'
+import { maintenanceWorkerFactory } from '../../../src/factories/maintenance-worker-factory'
+
+describe('maintenanceWorkerFactory', () => {
+  it('returns a MaintenanceWorker', () => {
+    expect(maintenanceWorkerFactory()).to.be.an.instanceOf(MaintenanceWorker)
+  })
+})