test(dtslint): add dtslint test for merge operator (#4093) (#4392)

* test(dtslint): add dtslint test for merge operator (#4093)

* test(dtslint): change dtslint test for merge operator to use helpers (#4093)

spec-dtslint/helpers.ts

@@ -0,0 +1,17 @@
+import { of } from 'rxjs';
+
+export class A { a = 0; }
+export class B { b = 0; }
+export class C { c = 0; }
+export class D { d = 0; }
+export class E { e = 0; }
+export class F { f = 0; }
+export class G { g = 0; }
+
+export const a = of(new A());
+export const b = of(new B());
+export const c = of(new C());
+export const d = of(new D());
+export const e = of(new E());
+export const f = of(new F());
+export const g = of(new G());

spec-dtslint/operators/merge-spec.ts

@@ -0,0 +1,88 @@
+import { of, asyncScheduler } from 'rxjs';
+import { merge } from 'rxjs/operators';
+import { A, B, C, D, E, F, G, a, b, c, d, e, f, g } from '../helpers';
+
+it('should accept no parameter', () => {
+  const res = a.pipe(merge()); // $ExpectType Observable<A>
+});
+
+it('should infer correctly with scheduler param', () => {
+  const res = a.pipe(merge(asyncScheduler)); // $ExpectType Observable<A>
+});
+
+it('should infer correctly with concurrent param', () => {
+  const res = a.pipe(merge(3)); // $ExpectType Observable<A>
+});
+
+it('should infer correctly with concurrent and scheduler param', () => {
+  const res = a.pipe(merge(3, asyncScheduler)); // $ExpectType Observable<A>
+});
+
+it('should infer correctly with 1 Observable param', () => {
+  const res = a.pipe(merge(b)); // $ExpectType Observable<A | B>
+});
+
+it('should infer correctly with 2 Observable param', () => {
+  const res = a.pipe(merge(b, c)); // $ExpectType Observable<A | B | C>
+});
+
+it('should infer correctly with 3 Observable param', () => {
+  const res = a.pipe(merge(b, c, d)); // $ExpectType Observable<A | B | C | D>
+});
+
+it('should infer correctly with 4 Observable param', () => {
+  const res = a.pipe(merge(b, c, d, e)); // $ExpectType Observable<A | B | C | D | E>
+});
+
+it('should infer correctly with 5 Observable param', () => {
+  const res = a.pipe(merge(b, c, d, e, f)); // $ExpectType Observable<A | B | C | D | E | F>
+});
+
+it('should infer correctly with 1 Observable and concurrent param', () => {
+  const res = a.pipe(merge(b, 1)); // $ExpectType Observable<A | B>
+});
+
+it('should infer correctly with 2 Observable and concurrent param', () => {
+  const res = a.pipe(merge(b, c, 1)); // $ExpectType Observable<A | B | C>
+});
+
+it('should infer correctly with 3 Observable and concurrent param', () => {
+  const res = a.pipe(merge(b, c, d, 1)); // $ExpectType Observable<A | B | C | D>
+});
+
+it('should infer correctly with 4 Observable and concurrent param', () => {
+  const res = a.pipe(merge(b, c, d, e, 1)); // $ExpectType Observable<A | B | C | D | E>
+});
+
+it('should infer correctly with 5 Observable and concurrent param', () => {
+  const res = a.pipe(merge(b, c, d, e, f, 1)); // $ExpectType Observable<A | B | C | D | E | F>
+});
+
+it('should infer correctly with 1 Observable, concurrent, and scheduler param', () => {
+  const res = a.pipe(merge(b, 1, asyncScheduler)); // $ExpectType Observable<A | B>
+});
+
+it('should infer correctly with 2 Observable, concurrent, and scheduler param', () => {
+  const res = a.pipe(merge(b, c, 1, asyncScheduler)); // $ExpectType Observable<A | B | C>
+});
+
+it('should infer correctly with 3 Observable, concurrent, and scheduler param', () => {
+  const res = a.pipe(merge(b, c, d, 1, asyncScheduler)); // $ExpectType Observable<A | B | C | D>
+});
+
+it('should infer correctly with 4 Observable, concurrent, and scheduler param', () => {
+  const res = a.pipe(merge(b, c, d, e, 1, asyncScheduler)); // $ExpectType Observable<A | B | C | D | E>
+});
+
+it('should infer correctly with 5 Observable, concurrent, and scheduler param', () => {
+  const res = a.pipe(merge(b, c, d, e, f, 1, asyncScheduler)); // $ExpectType Observable<A | B | C | D | E | F>
+});
+
+// TODO: Fix this when the both merge operator and merge creator function has been fix
+// see: https://github.com/ReactiveX/rxjs/pull/4371#issuecomment-441124096
+// Comment is about combineLater, but, it's the same problem to fix
+// it('should infer correctly with array param', () => {
+//   const res = of(1, 2, 3);
+//   const b = [of('a', 'b', 'c')];
+//   const res = a.pipe(merge(b)); // $ExpectType Observable<number|Observable<string>>
+// });