Function expectToBeUndefined

expectToBeUndefined(arg: unknown): asserts arg is undefined
Equivalent to calling vitest.expect(arg).toBeUndefined() while also asserting arg to be undefined.
Parameters
- arg: unknown
  The variable to be asserted.
Returns asserts arg is undefined
undefined.
Assert
arg is undefined.
Example
```
const iAmUndefined: number | undefined = Math.random() >= 0 ? 10 : undefined;
expectToBeUndefined(iAmUndefined);
expect(iAmUndefined + 1).toBe(11);
    // ^ 'iAmUndefined' is possibly 'undefined'.
```
- Defined in src/expect.ts:80