Update vitest and vitest coverage to 4.0.16

Author: EhabY

CLAUDE.md

@@ -28,6 +28,13 @@ Comments explain what code does or why it exists:
 - Never mock behavior in end-to-end tests - use real data
 - Mock as little as possible in unit tests - try to use real data
 - Find root causes, not symptoms. Read error messages carefully before attempting fixes.
+- When mocking constructors (classes) with `vi.mocked(...).mockImplementation()`, use regular functions, not arrow functions. Arrow functions can't be called with `new`.
+  ```typescript
+  // ✗ Wrong
+  vi.mocked(SomeClass).mockImplementation(() => mock);
+  // ✓ Correct
+  vi.mocked(SomeClass).mockImplementation(function () { return mock; });
+  ```
 
 ## Version Control
 

package.json

@@ -428,7 +428,7 @@
 		"@types/ws": "^8.18.1",
 		"@typescript-eslint/eslint-plugin": "^8.49.0",
 		"@typescript-eslint/parser": "^8.50.1",
-		"@vitest/coverage-v8": "^3.2.4",
+		"@vitest/coverage-v8": "^4.0.16",
 		"@vscode/test-cli": "^0.0.12",
 		"@vscode/test-electron": "^2.5.2",
 		"@vscode/vsce": "^3.7.1",
@@ -452,7 +452,7 @@
 		"ts-loader": "^9.5.4",
 		"typescript": "^5.9.3",
 		"utf-8-validate": "^6.0.6",
-		"vitest": "^3.2.4",
+		"vitest": "^4.0.16",
 		"vscode-test": "^1.5.0",
 		"webpack": "^5.104.1",
 		"webpack-cli": "^6.0.1"

test/unit/api/coderApi.test.ts

@@ -342,7 +342,7 @@ describe("CoderApi", () => {
 
 		it("falls back to SSE when WebSocket creation fails with 404", async () => {
 			// Only 404 errors trigger SSE fallback - other errors are thrown
-			vi.mocked(Ws).mockImplementation(() => {
+			vi.mocked(Ws).mockImplementation(function () {
 				throw new Error("Unexpected server response: 404");
 			});
 
@@ -380,7 +380,7 @@ describe("CoderApi", () => {
 		});
 
 		it("throws non-404 errors without SSE fallback", async () => {
-			vi.mocked(Ws).mockImplementation(() => {
+			vi.mocked(Ws).mockImplementation(function () {
 				throw new Error("Network error");
 			});
 
@@ -398,7 +398,7 @@ describe("CoderApi", () => {
 				let wsAttempts = 0;
 				const mockEventSources: MockEventSource[] = [];
 
-				vi.mocked(Ws).mockImplementation(() => {
+				vi.mocked(Ws).mockImplementation(function () {
 					wsAttempts++;
 					const mockWs = createMockWebSocket("wss://test", {
 						on: vi.fn((event: string, handler: (e: unknown) => void) => {
@@ -413,7 +413,7 @@ describe("CoderApi", () => {
 					return mockWs as Ws;
 				});
 
-				vi.mocked(EventSource).mockImplementation(() => {
+				vi.mocked(EventSource).mockImplementation(function () {
 					const es = createMockEventSource(`${CODER_URL}/api/v2/test`);
 					mockEventSources.push(es);
 					return es as unknown as EventSource;
@@ -436,7 +436,7 @@ describe("CoderApi", () => {
 
 	const setupAutoOpeningWebSocket = () => {
 		const sockets: Array<Partial<Ws>> = [];
-		vi.mocked(Ws).mockImplementation((url: string | URL) => {
+		vi.mocked(Ws).mockImplementation(function (url: string | URL) {
 			const mockWs = createMockWebSocket(String(url), {
 				on: vi.fn((event, handler) => {
 					if (event === "open") {
@@ -575,7 +575,7 @@ describe("CoderApi", () => {
 	describe("dispose", () => {
 		it("disposes all tracked reconnecting sockets", async () => {
 			const sockets: Array<Partial<Ws>> = [];
-			vi.mocked(Ws).mockImplementation((url: string | URL) => {
+			vi.mocked(Ws).mockImplementation(function (url: string | URL) {
 				const mockWs = createMockWebSocket(String(url), {
 					on: vi.fn((event, handler) => {
 						if (event === "open") {
@@ -701,9 +701,13 @@ function createMockEventSource(url: string): MockEventSource {
 }
 
 function setupWebSocketMock(ws: Partial<Ws>): void {
-	vi.mocked(Ws).mockImplementation(() => ws as Ws);
+	vi.mocked(Ws).mockImplementation(function () {
+		return ws as Ws;
+	});
 }
 
 function setupEventSourceMock(es: Partial<EventSource>): void {
-	vi.mocked(EventSource).mockImplementation(() => es as EventSource);
+	vi.mocked(EventSource).mockImplementation(function () {
+		return es as EventSource;
+	});
 }

test/unit/websocket/sseConnection.test.ts

@@ -356,7 +356,9 @@ function createMockEventSource(
 }
 
 function setupEventSourceMock(es: Partial<EventSource>): void {
-	vi.mocked(EventSource).mockImplementation(() => es as EventSource);
+	vi.mocked(EventSource).mockImplementation(function () {
+		return es as EventSource;
+	});
 }
 
 function waitForNextTick(): Promise<void> {