refactor: undo accidental change to internal isPromise helper

Author: benlesh

packages/rxjs/spec/util/isPromise-spec.ts

@@ -1,32 +1,32 @@
 import { of } from 'rxjs';
 import { expect } from 'chai';
-import { isThennable } from 'rxjs/internal/Observable';
+import { isPromise } from 'rxjs/internal/Observable';
 
 describe('isPromise', () => {
   it('should return true for new Promise', () => {
     const o = new Promise<any>(() => null);
-    expect(isThennable(o)).to.be.true;
+    expect(isPromise(o)).to.be.true;
   });
 
   it('should NOT return true for any Observable', () => {
     const o: any = of(null);
 
-    expect(isThennable(o)).to.be.false;
+    expect(isPromise(o)).to.be.false;
   });
 
   it('should return false for null', () => {
-    expect(isThennable(null)).to.be.false;
+    expect(isPromise(null)).to.be.false;
   });
 
   it('should return false for undefined', () => {
-    expect(isThennable(undefined)).to.be.false;
+    expect(isPromise(undefined)).to.be.false;
   });
 
   it('should return false for a number', () => {
-    expect(isThennable(1)).to.be.false;
+    expect(isPromise(1)).to.be.false;
   });
 
   it('should return false for a string', () => {
-    expect(isThennable('1')).to.be.false;
+    expect(isPromise('1')).to.be.false;
   });
 });

packages/rxjs/src/internal/Observable.ts

@@ -1231,7 +1231,7 @@ export function getObservableInputType(input: unknown): ObservableInputType {
   if (isArrayLike(input)) {
     return ObservableInputType.ArrayLike;
   }
-  if (isThennable(input)) {
+  if (isPromise(input)) {
     return ObservableInputType.Promise;
   }
   if (isAsyncIterable(input)) {
@@ -1287,7 +1287,7 @@ function isReadableStreamLike<T>(obj: any): obj is ReadableStreamLike<T> {
  * Tests to see if the object is "thennable".
  * @param value the object to test
  */
-export function isThennable(value: any): value is Thennable<any> {
+export function isPromise(value: any): value is Thennable<any> {
   return isFunction(value?.then);
 }
 

packages/rxjs/src/internal/types.ts

@@ -91,18 +91,14 @@ export interface Subscribable<T> {
   subscribe(observer: Partial<Observer<T>>): Unsubscribable;
 }
 
-export interface Thennable<T> {
-  then(onresolved: ((value: T) => void) | null | undefined, onrejected?: ((reason: any) => void) | null | undefined): void;
-}
-
 /**
  * Valid types that can be converted to observables.
  */
 export type ObservableInput<T> =
   | Observable<T>
   | InteropObservable<T>
   | AsyncIterable<T>
-  | Thennable<T>
+  | PromiseLike<T>
   | ArrayLike<T>
   | Iterable<T>
   | ReadableStreamLike<T>;