to be fulfilled with

• <Promise> to be fulfilled with <any>

Asserts that a promise is fulfilled with a specific value:

const promiseThatWillBeFulfilledWithAValue = new Promise(function (
  resolve,
  reject
) {
  setTimeout(function () {
    resolve('abc');
  }, 1);
});
 
return expect(
  promiseThatWillBeFulfilledWithAValue,
  'to be fulfilled with',
  'abc'
);

The expected value will be matched against the value with to satisfy semantics, so you can pass any of the values supported by to satisfy:

return expect(Promise.resolve('abc'), 'to be fulfilled with', /b/);

You get a nice diff if the assertion fails:

return expect(Promise.resolve('abc'), 'to be fulfilled with', 'def');

expected Promise to be fulfilled with 'def'
  
expected 'abc' to equal 'def'
 
abc
def