test(dtslint): add startWith tests

spec-dtslint/operators/startWith-spec.ts

@@ -0,0 +1,33 @@
+import { of, asyncScheduler  } from 'rxjs';
+import { startWith } from 'rxjs/operators';
+import { TestScheduler } from 'rxjs/testing';
+
+declare const rxTestScheduler: TestScheduler;
+
+it('should infer correctly with one value', () => {
+  const o = of(1, 2, 3).pipe(startWith(4)); // $ExpectType Observable<number>
+});
+
+it('should infer correctly with multiple values', () => {
+  const o = of(1, 2, 3).pipe(startWith(4, 5, 6)); // $ExpectType Observable<number>
+});
+
+it('should infer correctly with no value', () => {
+  const o = of(1, 2, 3).pipe(startWith()); // $ExpectType Observable<number>
+});
+
+it('should infer correctly with a value and a scheduler', () => {
+  const o = of(1, 2, 3).pipe(startWith(5, asyncScheduler)); // $ExpectType Observable<number>
+});
+
+it('should infer correctly with only a scheduler', () => {
+  const o = of(1, 2, 3).pipe(startWith(asyncScheduler)); // $ExpectType Observable<number>
+});
+
+it('should enforce types with one value', () => {
+  const o = of(1, 2, 3).pipe(startWith('foo')); // $ExpectError
+});
+
+it('should enforce types with multiple value', () => {
+  const o = of(1, 2, 3).pipe(startWith(4, 'foo')); // $ExpectError
+});