Added unit tests to cover exception handling in secure-storage; Fixed…

… a minor issue (#276)

src/lib/secure-storage/index.test.tsx

@@ -0,0 +1,34 @@
+import { mocked } from 'ts-jest/utils'
+
+import { setItem, getItem } from './storage'
+const { saveObject, getObject } = jest.requireActual('./index')
+
+jest.mock('./storage', () => ({
+  setItem: jest.fn(),
+  getItem: jest.fn(),
+}))
+
+const getItemMocked = mocked(getItem)
+const setItemMocked = mocked(setItem)
+
+describe('storage', () => {
+  afterEach(() => {
+    getItemMocked.mockClear()
+    setItemMocked.mockClear()
+  })
+
+  it('saveObject to reject when exception occurs in setItem', async () => {
+    setItemMocked.mockRejectedValueOnce('setItem error')
+    await expect(saveObject('foo', 'bar')).rejects.toEqual('setItem error')
+  })
+
+  it('getObject to return null when exception occurs in getItem', async () => {
+    getItemMocked.mockRejectedValueOnce('getItem error')
+    await expect(getObject('foo')).resolves.toBeNull()
+  })
+
+  it('getObject to return null when exception occurs in JSON.parse', async () => {
+    getItemMocked.mockResolvedValueOnce('bad json')
+    await expect(getObject('foo')).resolves.toBeNull()
+  })
+})

src/lib/secure-storage/storage.test.tsx

@@ -0,0 +1,72 @@
+import { writeAsStringAsync, readAsStringAsync } from 'expo-file-system'
+import { getItemAsync, setItemAsync } from 'expo-secure-store'
+import { mocked } from 'ts-jest/utils'
+const { setItem, getItem } = jest.requireActual('./storage')
+
+jest.mock('expo-file-system', () => ({
+  writeAsStringAsync: jest.fn(),
+  getInfoAsync: jest.fn().mockReturnValue({ exists: true }),
+  readAsStringAsync: jest.fn(),
+}))
+
+jest.mock('expo-secure-store', () => ({
+  getItemAsync: jest.fn(),
+  setItemAsync: jest.fn(),
+}))
+
+global.crypto = {
+  getRandomValues: jest.fn().mockReturnValue(new Uint8Array(32)),
+}
+
+const writeAsStringAsyncMocked = mocked(writeAsStringAsync)
+const readAsStringAsyncMocked = mocked(readAsStringAsync)
+const getItemAsyncMocked = mocked(getItemAsync)
+const setItemAsyncMocked = mocked(setItemAsync)
+
+describe('storage', () => {
+  afterEach(() => {
+    writeAsStringAsyncMocked.mockClear()
+    readAsStringAsyncMocked.mockClear()
+    getItemAsyncMocked.mockClear()
+    setItemAsyncMocked.mockClear()
+  })
+
+  it('setItem to reject when exception occurs in readAsStringAsync', async () => {
+    readAsStringAsyncMocked.mockRejectedValueOnce('readAsStringAsync error')
+    await expect(setItem('foo', 'bar')).rejects.toEqual(
+      'readAsStringAsync error'
+    )
+  })
+
+  it('setItem to reject when exception occurs in setItemAsync', async () => {
+    setItemAsyncMocked.mockRejectedValueOnce('setItemAsync error')
+    readAsStringAsyncMocked.mockReturnValueOnce(null)
+    await expect(setItem('foo', 'bar')).rejects.toEqual('setItemAsync error')
+  })
+
+  it('setItem to reject when exception occurs in writeAsStringAsync', async () => {
+    setItemAsyncMocked.mockResolvedValueOnce()
+    readAsStringAsyncMocked.mockReturnValueOnce(null)
+    writeAsStringAsyncMocked.mockRejectedValueOnce('writeAsStringAsync error')
+    await expect(setItem('foo', 'bar')).rejects.toEqual(
+      'writeAsStringAsync error'
+    )
+  })
+
+  it('getItem to reject when exception occurs in readAsStringAsync', async () => {
+    readAsStringAsyncMocked.mockRejectedValueOnce('readAsStringAsync error')
+    await expect(getItem('foo')).rejects.toEqual('readAsStringAsync error')
+  })
+
+  it('getItem to reject when getItemAsync returns null', async () => {
+    readAsStringAsyncMocked.mockResolvedValueOnce('encrypted_storage_key')
+    getItemAsyncMocked.mockResolvedValueOnce(null)
+    await expect(getItem('foo')).rejects.toEqual('Storage key not found')
+  })
+
+  it('getItem to reject when exception occurs in getItemAsyncMocked', async () => {
+    readAsStringAsyncMocked.mockResolvedValueOnce('encrypted_storage_key')
+    getItemAsyncMocked.mockRejectedValueOnce('getItemAsync error')
+    await expect(getItem('foo')).rejects.toEqual('getItemAsync error')
+  })
+})

src/lib/secure-storage/storage.ts

@@ -51,7 +51,7 @@ const getDecryptedStorage = async () => {
   const encryptedStorage = await FileSystem.readAsStringAsync(
     storageFileNameURI
   )
-  if (encryptedStorage.length === 0) {
+  if (!encryptedStorage || encryptedStorage.length === 0) {
     return {}
   }