message: chore(test): fix debounce types
diff: @@ -4,14 +4,14 @@ import { debounce, mergeMap, mapTo } from 'rxjs/operators';
  import { TestScheduler } from 'rxjs/testing';
  import { hot, cold, expectObservable, expectSubscriptions } from '../helpers/marble-testing';
  -declare const type;
  +declare const type: Function;
  declare function asDiagram(arg: string): Function;
  declare const rxTestScheduler: TestScheduler;
  /** @test {debounce} */
  describe('debounce operator', () => {
  - function getTimerSelector(x) {
  + function getTimerSelector(x: number) {
  return () => timer(x, rxTestScheduler);
  }
  @@ -287,7 +287,7 @@ describe('debounce operator', () => {
  [' ^! ',
  ' ^ ! '];
  - function selectorFunction(x) {
  + function selectorFunction(x: string) {
  if (x !== 'c') {
  return selector.shift();
  } else {
  @@ -307,7 +307,7 @@ describe('debounce operator', () => {
  const e1subs = '^ !';
  const expected = '--------a-x-yz---bxy---z--c--x--y--z|';
  - function selectorFunction(x) { return EMPTY; }
  + function selectorFunction(x: string) { return EMPTY; }
  expectObservable(e1.pipe(debounce(selectorFunction))).toBe(expected);
  expectSubscriptions(e1.subscriptions).toBe(e1subs);
  @@ -420,8 +420,8 @@ describe('debounce operator', () => {
  });
  it('should debounce correctly when synchronously reentered', () => {
  - const results = [];
  - const source = new Subject();
  + const results: number[] = [];
  + const source = new Subject<number>();
  source.pipe(debounce(() => of(null))).subscribe(value => {
  results.push(value);
  