feat(maybeAsync): allow from to accept Promise of None

Author: seangwright

src/maybeAsync.ts

@@ -11,6 +11,7 @@ import {
   isPromise,
   MaybeMatcher,
   MaybeMatcherNoReturn,
+  None,
   pipeFromArray,
   Some,
 } from './utilities';
@@ -26,10 +27,12 @@ export class MaybeAsync<TValue> {
    */
   static from<TValue>(maybe: Maybe<TValue>): MaybeAsync<TValue>;
   static from<TValue>(maybePromise: Promise<Maybe<TValue>>): MaybeAsync<TValue>;
-  static from<TValue>(promise: Promise<Some<TValue>>): MaybeAsync<TValue>;
+  static from<TValue>(
+    promise: Promise<Some<TValue> | None>
+  ): MaybeAsync<TValue>;
   static from<TValue>(
     valueOrPromiseOrMaybePromise:
-      | Promise<Some<TValue> | Maybe<TValue>>
+      | Promise<Some<TValue> | None | Maybe<TValue>>
       | Maybe<TValue>
   ): MaybeAsync<TValue> {
     if (isPromise(valueOrPromiseOrMaybePromise)) {

test/maybeAsync/maybeAsync.spec.ts

@@ -47,6 +47,16 @@ describe('MaybeAsync', () => {
 
       await expect(sut.toPromise()).rejects.toMatch(error);
     });
+
+    test('constructs with a Promise undefined value', async () => {
+      const sut = MaybeAsync.from(
+        Promise.resolve<string | undefined>(undefined)
+      );
+
+      const innerMaybe = await sut.toPromise();
+
+      expect(innerMaybe).toHaveNoValue();
+    });
   });
 
   describe('some', () => {