fix: Mock EventEmitter (#269)

src/vscode-mock.ts

@@ -36,6 +36,7 @@ import {
     EndOfLine,
     EnvironmentVariableMutatorType,
     EvaluatableExpression,
+    EventEmitter,
     ExtensionKind,
     ExtensionMode,
     FileChangeType,
@@ -94,7 +95,6 @@ type NotImplemented =
     | 'CancellationError'
     | 'CancellationTokenSource'
     | 'CodeActionTriggerKind'
-    | 'EventEmitter'
     | 'Hover'
     | 'InlineValueText'
     | 'InlineValueVariableLookup'
@@ -245,6 +245,7 @@ export function createVSCodeMock(jest: TestFramework): VSCodeMock {
         EndOfLine,
         EnvironmentVariableMutatorType,
         EvaluatableExpression,
+        EventEmitter,
         ExtensionKind,
         ExtensionMode,
         FileChangeType,

src/vscode/EventEmitter.test.ts

@@ -0,0 +1,26 @@
+import { describe, expect, jest, test } from '@jest/globals';
+
+import { EventEmitter } from './EventEmitter';
+
+describe('EventEmitter', () => {
+    test('fire', () => {
+        const emitter = new EventEmitter<string>();
+        const listener = jest.fn();
+        const listener2 = jest.fn();
+        emitter.event(listener);
+        emitter.event(listener2);
+        emitter.fire('foo');
+        expect(listener).toHaveBeenCalledWith('foo');
+        expect(listener2).toHaveBeenCalledWith('foo');
+    });
+
+    test('dispose', () => {
+        const emitter = new EventEmitter<string>();
+        const listener = jest.fn();
+        const disposable = emitter.event(listener);
+        emitter.fire('foo');
+        disposable.dispose();
+        emitter.fire('bar');
+        expect(listener).toHaveBeenCalledWith('foo');
+    });
+});

src/vscode/EventEmitter.ts

@@ -0,0 +1,55 @@
+/* eslint-disable @typescript-eslint/no-explicit-any */
+// eslint-disable-next-line node/no-missing-import
+import type * as vscode from 'vscode';
+
+type Disposable = vscode.Disposable;
+
+type Listener<T> = (e: T) => any;
+
+export class EventEmitter<T> implements vscode.EventEmitter<T> {
+    readonly #listeners = new Set<Listener<T>>();
+
+    /**
+     * The event listeners can subscribe to.
+     */
+    event(listener: (e: T) => any, thisArgs?: any, disposables?: Disposable[]): Disposable {
+        const fn = thisArgs ? listener.bind(thisArgs) : listener;
+        this.#listeners.add(fn);
+        const disposable = {
+            dispose: () => {
+                this.#listeners.delete(fn);
+            },
+        };
+
+        if (disposables) {
+            disposables.push(disposable);
+        }
+
+        return disposable;
+    }
+
+    /**
+     * Notify all subscribers of the {@link EventEmitter.event event}. Failure
+     * of one or more listener will not fail this function call.
+     *
+     * @param data The event object.
+     */
+    fire(data: T): void {
+        for (const listener of this.#listeners) {
+            try {
+                listener(data);
+            } catch {
+                // ignore
+            }
+        }
+    }
+
+    /**
+     * Dispose this object and free resources.
+     */
+    dispose(): void {
+        this.#listeners.clear();
+    }
+
+    constructor() {}
+}

src/vscode/index.ts

@@ -21,3 +21,4 @@ export * from './uri';
 export { createWindow } from './window';
 export type { Window } from './window';
 export { MockWorkspace, Workspace, createWorkspace } from './workspace';
+export { EventEmitter } from './EventEmitter';