startWith missing an 'empty' signature

[cartant]

Bug Report

The startWith operator includes a test for its being called with only a scheduler:

it('should start with empty if given value is not specified', () => {
  const e1 =   hot('-a-|');
  const e1subs =   '^  !';
  const expected = '-a-|';

  expectObservable(e1.pipe(startWith(rxTestScheduler))).toBe(expected);
  expectSubscriptions(e1.subscriptions).toBe(e1subs);
});

However there is no associated overload signature:

/* tslint:disable:max-line-length */
export function startWith<T>(v1: T, scheduler?: SchedulerLike): MonoTypeOperatorFunction<T>;
export function startWith<T>(v1: T, v2: T, scheduler?: SchedulerLike): MonoTypeOperatorFunction<T>;
export function startWith<T>(v1: T, v2: T, v3: T, scheduler?: SchedulerLike): MonoTypeOperatorFunction<T>;
export function startWith<T>(v1: T, v2: T, v3: T, v4: T, scheduler?: SchedulerLike): MonoTypeOperatorFunction<T>;
export function startWith<T>(v1: T, v2: T, v3: T, v4: T, v5: T, scheduler?: SchedulerLike): MonoTypeOperatorFunction<T>;
export function startWith<T>(v1: T, v2: T, v3: T, v4: T, v5: T, v6: T, scheduler?: SchedulerLike): MonoTypeOperatorFunction<T>;
export function startWith<T>(...array: Array<T | SchedulerLike>): MonoTypeOperatorFunction<T>;
/* tslint:enable:max-line-length */

Possible Solution

Add an overload signature that takes only a scheduler.

[cartant]

To work around this in PR #3945, the expectation was changed to:

expectObservable(e1.pipe(startWith<any>(rxTestScheduler))).toBe(expected);

When the overload signature is added, the <any> should be removed.