fix: make initDatabase idempotent to prevent empty history after sync

tests/database.test.ts

@@ -1,4 +1,3 @@
-import { initDatabase, insertMeasurement, getAllMeasurements, getLatestMeasurement, updateMeasurement } from '../src/database/db'
 import { Measurement } from '../src/types'
 import * as SQLite from 'expo-sqlite'
 
@@ -24,14 +23,30 @@ const mockMeasurement: Measurement = {
 
 describe('database', () => {
   let db: any
+  let initDatabase: any
+  let insertMeasurement: any
+  let getAllMeasurements: any
+  let getLatestMeasurement: any
+  let updateMeasurement: any
 
-  beforeEach(() => {
+  beforeEach(async () => {
+    jest.resetModules()
+    jest.doMock('expo-sqlite', () => ({
+      openDatabaseAsync: jest.fn(),
+    }))
     db = {
       execAsync: jest.fn(),
       runAsync: jest.fn(),
       getAllAsync: jest.fn(),
     }
-    ;(SQLite.openDatabaseAsync as jest.Mock).mockResolvedValue(db)
+    const sqlite = require('expo-sqlite')
+    ;(sqlite.openDatabaseAsync as jest.Mock).mockResolvedValue(db)
+    const mod = require('../src/database/db')
+    initDatabase = mod.initDatabase
+    insertMeasurement = mod.insertMeasurement
+    getAllMeasurements = mod.getAllMeasurements
+    getLatestMeasurement = mod.getLatestMeasurement
+    updateMeasurement = mod.updateMeasurement
   })
 
   it('initDatabase creates the measurements table', async () => {