Trying to mock nfcManager using react native testing library, but it doesn't work & nfcManager.start()

[PanosPapad]

Hello,

I am developing an android app that requires to read nfc tags, so I am using this library. However, I have come across two issues that I could not figure out at all.

• What does the nfcManager.start() function do? I realized that the app was working even if I remove it from the top of the method.
• I want to test the page, so I try to mock nfcManager. However, I always get this issue TypeError: _reactNativeNfcManager.default.start is not a function or TypeError: _reactNativeNfcManager.default.isSupported is not a function etc with all the functions of the interface. What I try to do is

const mockNfcManager = jest.fn();

jest.mock("react-native-nfc-manager", ()=>({ NfcManagerModule: { start: mockNfcManager, }, }));

and then render the component and check if expect(mockedNavigate).toHaveBeenCalled()

Sorry for the long message, but I saw you are pretty responsive in the issues of this library, and also I have not seen anyone mentioning these issues anywhere, so I was hoping to solve this issue here :) Thanks a lot!

[dylanclements]

This worked for me at the top level of my test scripts. Alternatively you could also place this in a __mocks__ folder in your root directory and include it in your setupFiles in jest.config.js

jest.mock('react-native-nfc-manager', () => ({
  start: () => Promise.resolve(),
}));

[whitedogg13]

Hi @PanosPapad , sorry for the late response.

The start() function is simply used to initialize the native layer.

Regarding the mock, I think @dylanclements 's suggestion should work:

jest.mock('react-native-nfc-manager', () => ({
  start: () => Promise.resolve(),
  isSupported: () => Promise.resolve(false), // bypass NFC feature when running test cases
}));

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