Jest assertions

A value is not undefined

To test that a string value is not undefined in a Jest test, you can use the toBeDefined() matcher.

Here is an example of how to use this matcher:

test('string is not undefined', () => {
  const str = 'hello';
  expect(str).toBeDefined();
});

This test will pass if the value of str is not undefined.

You can also use the not modifier to test that a value is undefined. For example:

test('string is not undefined', () => {
  const str = 'hello';
  expect(str).not.toBe(undefined);
});

I hope this helps. Let me know if you have any questions or need further assistance.