What is the best way to simulate a primitive value for a specific test only?

For a particular test, I need the value of isBanana to be false.

It has been successful when I mocked the function in the main index.test.js file. However, this caused issues with other tests that require isBanana to be true.

jest.mock("myapp-api-functions", () => {
  console.log(`executing mock function`);
  return {
    ...jest.requireActual("myapp-api-functions"),
    isBanana: false,
  };
});

When attempting to move the jest.mock() inside the body of the test, the value of isBanana reverts to true and the test fails.

it(`should error when someone tries to use the mock account in production`, async () => {
  jest.mock("myapp-api-functions", () => {
    console.log(`executing mock function`);
    return {
      ...jest.requireActual("myapp-api-functions"),
      isBanana: false,
    };
  });

...same test function that previously passed...
});

The mocking approach does not seem to work for this specific scenario, resulting in test failure.

Is there a way to effectively mock the primitive value for just one test?

Answer №1

The hoisting of calls to jest.mock occurs at the beginning of the code block.

If you want to prevent this behavior, you can opt for using jest.doMock instead as shown below:

it(`should throw an error if attempting to use a mocked account in production`, async () => {
  jest.doMock("myapp-api-functions", () => {
    console.log(`executing mock function`);
    return {
      ...jest.requireActual("myapp-api-functions"),
      isBanana: false,
    };
  });

  // Same test logic as before...
});

By doing so, you are able to define specific mock behaviors for individual tests.

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