Awaits the asyncFn promise or, if asyncFn is a function, immediately calls the function and awaits the returned promise to complete. It will then check that the promise is not rejected.

If asyncFn is a function and it throws an error synchronously, assert.doesNotReject() will return a rejected Promise with that error. If the function does not return a promise, assert.doesNotReject() will return a rejected Promise with an ERR_INVALID_RETURN_VALUE error. In both cases the error handler is skipped.

Using assert.doesNotReject() is actually not useful because there is little benefit in catching a rejection and then rejecting it again. Instead, consider adding a comment next to the specific code path that should not reject and keep error messages as expressive as possible.

If specified, error can be a Class, RegExp, or a validation function. See throws for more details.

Besides the async nature to await the completion behaves identically to doesNotThrow.

import assert from 'node:assert/strict';

await assert.doesNotReject(
  async () => {
    throw new TypeError('Wrong value');
  },
  SyntaxError,
);

import assert from 'node:assert/strict';

assert.doesNotReject(Promise.reject(new TypeError('Wrong value')))
  .then(() => {
    // ...
  });