fix: use empty cancellation reason as default (#32)

* fix: use empty cancellation `reason` as default

Let clients cancel the token without any reason via a convenient way.

Signed-off-by: dankeboy36 <[email protected]>

* fix: remove superfluous type declaration

it can be inferred from the default empty `string`

Signed-off-by: dankeboy36 <[email protected]>

* Make reason parameter optional + test

---------

Signed-off-by: dankeboy36 <[email protected]>
Co-authored-by: Dennis Huebner <[email protected]>

packages/vscode-messenger-common/src/cancellation.ts

@@ -22,31 +22,31 @@ export class Deferred<R = any> {
 
 /**
 * Implementation of the CancellationToken interface.
-* Allows to trigger cancelation.
+* Allows to trigger cancellation.
 */
 export class CancellationTokenImpl implements CancellationToken {
     private canceled = false;
-    private listeners: Array<((reason: string) => void)> = [];
+    private listeners: Array<((reason?: string) => void)> = [];
 
-    public cancel(reason: string): void {
+    public cancel(reason?: string): void {
         if (this.canceled) {
             throw new Error('Request was already canceled.');
         }
         this.canceled = true;
-        this.listeners.forEach(callBack => callBack(reason));
+        this.listeners.forEach(callback => callback(reason));
         this.listeners = [];
     }
 
     get isCancellationRequested(): boolean {
         return this.canceled;
     }
 
-    public onCancellationRequested(callBack: (reason: string) => void): Disposable {
-        this.listeners.push(callBack);
+    public onCancellationRequested(callback: (reason?: string) => void): Disposable {
+        this.listeners.push(callback);
         const listeners = this.listeners;
         return {
             dispose() {
-                listeners.splice(listeners.indexOf(callBack), 1);
+                listeners.splice(listeners.indexOf(callback), 1);
             }
         };
     }

packages/vscode-messenger-common/src/messages.ts

@@ -188,7 +188,7 @@ export interface MessengerAPI {
  */
 export interface CancellationToken {
     readonly isCancellationRequested: boolean;
-    onCancellationRequested(callBack: (reason: string) => void): Disposable;
+    onCancellationRequested(callBack: (reason?: string) => void): Disposable;
 }
 
 /**

packages/vscode-messenger/tests/messenger.test.ts

@@ -525,6 +525,22 @@ describe('Extension Messenger', () => {
         expect((cancel as any).listeners.length).toBe(0);
     });
 
+    test('Cancel request - no reason', async () => {
+        const messenger = new Messenger();
+        messenger.registerWebviewView(view1);
+        const cancel: CancellationTokenImpl = new CancellationTokenImpl();
+        setTimeout(() =>
+            cancel.cancel(), 300);
+        await messenger.sendRequest(simpleRequest, ViewParticipant(VIEW_TYPE_1), FORCE_HANDLER_TO_WAIT_PARAM, cancel)
+            .then(() => {
+                throw new Error('Expected to throw error');
+            }).catch((error) => {
+                expect(error.message).toBe('');
+            });
+        // check the internal cancelation listener attached in `sendRequestToWebview` was removed
+        expect((cancel as any).listeners.length).toBe(0);
+    });
+
     test('Handle cancel request', async () => {
         const messenger = new Messenger();
         messenger.registerWebviewView(view1);