when fulfilled

• <Promise> when fulfilled <assertion>

Wait for a promise to be fulfilled, then delegate the value to another assertion.

const fulfilledPromise = new Promise(function (resolve, reject) {
  setTimeout(function () {
    resolve(123);
  }, 1);
});
 
return expect(fulfilledPromise, 'when fulfilled', 'to equal', 123);

It works with any assertion or expect.it construct:

return expect(
  Promise.resolve(123),
  'when fulfilled',
  expect.it('to be greater than', 100)
);

If the response is rejected, the assertion fails with the following output:

const rejectedPromise = new Promise(function (resolve, reject) {
  setTimeout(function () {
    reject(new Error('argh'));
  }, 1);
});
 
return expect(rejectedPromise, 'when fulfilled', 'to equal', 123);

expected Promise when fulfilled to equal 123
  
Promise unexpectedly rejected with Error('argh')