fixes issue where AsyncResult onSuccess and onFailure did not handle promises well

Author: everweij

package.json

@@ -1,7 +1,7 @@
 {
 	"private": false,
 	"name": "typescript-result",
-	"version": "2.1.0",
+	"version": "2.1.1",
 	"description": "A Result type inspired by Rust and Kotlin that leverages TypeScript's powerful type system to simplify error handling and make your code more readable and maintainable.",
 	"keywords": [
 		"result",

src/result.test.ts

@@ -1886,6 +1886,16 @@ describe("AsyncResult", () => {
 				expect(spy).toHaveBeenCalled();
 			});
 
+			it("handles callbacks that return a promise as well", async () => {
+				const result = AsyncResult.error(errorA);
+
+				const spy = vi.fn();
+
+				await result.onFailure(() => Promise.resolve().then(sleep).then(spy));
+
+				expect(spy).toHaveBeenCalled();
+			});
+
 			it("throws an error when the callback throws an error", async () => {
 				await expect(() =>
 					AsyncResult.error(errorA).onFailure(() => {
@@ -1944,6 +1954,16 @@ describe("AsyncResult", () => {
 					}),
 				).rejects.toThrow(CustomError);
 			});
+
+			it("handles callbacks that return a promise as well", async () => {
+				const result = AsyncResult.ok(12);
+
+				const spy = vi.fn();
+
+				await result.onSuccess(() => Promise.resolve().then(sleep).then(spy));
+
+				expect(spy).toHaveBeenCalled();
+			});
 		});
 
 		describe("map", () => {

src/result.ts

@@ -212,11 +212,15 @@ export class AsyncResult<Value, Err> extends Promise<Result<Value, Err>> {
 	 *   .map((value) => value * 2); // proceed with other operations
 	 * ```
 	 */
-	onFailure(action: (error: Err) => void): AsyncResult<Value, Err> {
+	onFailure(
+		action: (error: Err) => void | Promise<void>,
+	): AsyncResult<Value, Err> {
 		return new AsyncResult<Value, Err>((resolve, reject) =>
 			this.then(async (result) => {
 				try {
-					await result.onFailure(action);
+					if (result.isError()) {
+						await action(result.error as Err);
+					}
 					resolve(result);
 				} catch (e) {
 					reject(e);
@@ -254,11 +258,15 @@ export class AsyncResult<Value, Err> extends Promise<Result<Value, Err>> {
 	 * const asyncResult = await result.onSuccess(async (value) => someAsyncOperation(value));
 	 * ```
 	 */
-	onSuccess(action: (value: Value) => void): AsyncResult<Value, Err> {
+	onSuccess(
+		action: (value: Value) => void | Promise<void>,
+	): AsyncResult<Value, Err> {
 		return new AsyncResult<Value, Err>((resolve, reject) =>
 			this.then(async (result) => {
 				try {
-					await result.onSuccess(action);
+					if (result.isOk()) {
+						await action(result.value as Value);
+					}
 					resolve(result);
 				} catch (error) {
 					reject(error);