test: add unit tests for LIDMappingStore and message processing utilities (#1949)

* test: add unit tests for LIDMappingStore and message processing utilities

* Update src/__tests__/Signal/lid-mapping.test.ts

Co-authored-by: Rajeh Taher <rajeh@reforward.dev>

* Update src/__tests__/Utils/process-message.test.ts

Co-authored-by: Rajeh Taher <rajeh@reforward.dev>

* Update src/__tests__/Utils/process-message.test.ts

Co-authored-by: Rajeh Taher <rajeh@reforward.dev>

---------

Co-authored-by: Rajeh Taher <rajeh@reforward.dev>

src/__tests__/Signal/lid-mapping.test.ts

@@ -0,0 +1,47 @@
+import { jest } from '@jest/globals'
+import P from 'pino'
+import { LIDMappingStore } from '../../Signal/lid-mapping'
+import type { LIDMapping, SignalDataTypeMap, SignalKeyStoreWithTransaction } from '../../Types'
+
+const HOSTED_DEVICE_ID = 99
+
+const mockKeys: jest.Mocked<SignalKeyStoreWithTransaction> = {
+	get: jest.fn<SignalKeyStoreWithTransaction['get']>() as any,
+	set: jest.fn<SignalKeyStoreWithTransaction['set']>(),
+	transaction: jest.fn<SignalKeyStoreWithTransaction['transaction']>(async (work: () => any) => await work()) as any,
+	isInTransaction: jest.fn<SignalKeyStoreWithTransaction['isInTransaction']>()
+}
+const logger = P({ level: 'silent' })
+
+describe('LIDMappingStore', () => {
+	const mockPnToLIDFunc = jest.fn<(jids: string[]) => Promise<LIDMapping[] | undefined>>()
+	let lidMappingStore: LIDMappingStore
+
+	beforeEach(() => {
+		jest.clearAllMocks()
+		lidMappingStore = new LIDMappingStore(mockKeys, logger, mockPnToLIDFunc)
+	})
+
+	describe('getPNForLID', () => {
+		it('should correctly map a standard LID with a hosted device ID back to a standard PN with a hosted device', async () => {
+			const lidWithHostedDevice = `12345:${HOSTED_DEVICE_ID}@lid`
+			const pnUser = '54321'
+
+			// @ts-ignore
+			mockKeys.get.mockResolvedValue({ [`12345_reverse`]: pnUser } as SignalDataTypeMap['lid-mapping'])
+
+			const result = await lidMappingStore.getPNForLID(lidWithHostedDevice)
+			expect(result).toBe(`${pnUser}:${HOSTED_DEVICE_ID}@s.whatsapp.net`)
+		})
+
+		it('should return null if no reverse mapping is found', async () => {
+			const lid = 'nonexistent@lid'
+
+			// @ts-ignore
+			mockKeys.get.mockResolvedValue({} as SignalDataTypeMap['lid-mapping']) // Simulate not found in DB
+
+			const result = await lidMappingStore.getPNForLID(lid)
+			expect(result).toBeNull()
+		})
+	})
+})