Migrate to Vitest 4

package.json

@@ -55,7 +55,7 @@
     "tsconfig-paths-webpack-plugin": "^4.1.0",
     "typescript": "^5.9.0",
     "vite": "^6.4.2",
-    "vitest": "^2.1.9",
+    "vitest": "^4.1.0",
     "vscode-languageserver-protocol": "^3.17.3",
     "vscode-languageserver-textdocument": "^1.0.8",
     "webpack": "^5.94.0",

packages/prettier-plugin-liquid/vitest.config.mjs

@@ -6,12 +6,8 @@ export default defineConfig({
   test: {
     exclude: [...configDefaults.exclude],
     pool: 'forks',
-    poolOptions: {
-      forks: {
-        singleFork: true,
-        isolate: true,
-      },
-    },
+    maxWorkers: 1,
+    isolate: true,
     globalSetup: ['./src/test/test-setup.js'],
     setupFiles: ['../liquid-html-parser/build/shims.js'],
   },

packages/theme-check-common/package.json

@@ -41,7 +41,8 @@
   "devDependencies": {
     "@types/line-column": "^1.0.0",
     "@types/lodash": "^4.17.20",
+    "@types/node": "^22.18.8",
     "@types/postcss-safe-parser": "^5.0.4",
-    "@vitest/expect": "2.1.9"
+    "@vitest/expect": "4.1.0"
   }
 }

packages/theme-check-common/src/test/test-setup.ts

@@ -3,16 +3,6 @@ import { containOffense } from './contain-offense';
 import { OfferFixAssertion } from './chai-offer-fix-assertion';
 import { SuggestAssertion } from './chai-suggest-assertion';
 
-// Undocumented, but chai/utils has `.eql` for deep equality checks
-declare global {
-  export namespace Chai {
-    interface ChaiUtils {
-      /** deep equality */
-      eql: (a: any, b: any) => boolean;
-    }
-  }
-}
-
 /**
  * Setup chai extensions
  *

packages/theme-graph/package.json

@@ -36,6 +36,7 @@
     "vscode-uri": "^3.0.7"
   },
   "devDependencies": {
-    "@shopify/theme-check-node": "^3.26.0"
+    "@shopify/theme-check-node": "^3.26.0",
+    "@types/node": "^22.18.8"
   }
 }

packages/theme-language-server-common/package.json

@@ -39,6 +39,7 @@
     "vscode-uri": "^3.0.7"
   },
   "devDependencies": {
-    "@vitest/expect": "2.1.9"
+    "@types/node": "^22.18.8",
+    "@vitest/expect": "4.1.0"
   }
 }

packages/theme-language-server-common/src/formatting/providers/HtmlElementAutoclosingOnTypeFormattingProvider.spec.ts

@@ -2,6 +2,7 @@ import { afterEach, assert, beforeEach, describe, expect, it, vi } from 'vitest'
 import { DocumentOnTypeFormattingParams } from 'vscode-languageserver';
 import { DocumentManager } from '../../documents';
 import { OnTypeFormattingProvider } from '../OnTypeFormattingProvider';
+import type { SetCursorPosition } from '../types';
 
 const options: DocumentOnTypeFormattingParams['options'] = {
   insertSpaces: true,
@@ -11,11 +12,11 @@ const options: DocumentOnTypeFormattingParams['options'] = {
 describe('Module: HtmlElementAutoclosingOnTypeFormattingProvider', () => {
   let documentManager: DocumentManager;
   let onTypeFormattingProvider: OnTypeFormattingProvider;
-  let setCursorPositionSpy: ReturnType<typeof vi.fn>;
+  let setCursorPositionSpy: ReturnType<typeof vi.fn<SetCursorPosition>>;
   const uri = 'file:///path/to/document.liquid';
 
   beforeEach(() => {
-    setCursorPositionSpy = vi.fn();
+    setCursorPositionSpy = vi.fn<SetCursorPosition>();
     documentManager = new DocumentManager();
     onTypeFormattingProvider = new OnTypeFormattingProvider(documentManager, setCursorPositionSpy);
     vi.useFakeTimers();

packages/theme-language-server-common/src/test/MockConnection.ts

@@ -16,6 +16,26 @@ import {
 } from 'vscode-languageserver';
 import { path } from '@shopify/theme-check-common';
 
+type MockFn = ReturnType<typeof vi.fn>;
+
+type ProtocolConnectionSpies = {
+  dispose: MockFn;
+  end: MockFn;
+  hasPendingResponse: MockFn;
+  listen: MockFn;
+  onClose: MockFn;
+  onDispose: MockFn;
+  onError: MockFn;
+  onProgress: MockFn;
+  onNotification: MockFn;
+  onRequest: MockFn;
+  onUnhandledNotification: MockFn;
+  sendNotification: MockFn;
+  sendProgress: MockFn;
+  sendRequest: MockFn;
+  trace: MockFn;
+};
+
 type MockConnectionMethods = {
   /** Trigger all appropriate onNotification handlers on the connection */
   triggerNotification: ReturnType<typeof createConnection>['sendNotification'];
@@ -38,7 +58,7 @@ type MockConnectionMethods = {
   /** Perform the textDocument/didSave notification */
   saveDocument(relativePath: string): void;
 
-  spies: ReturnType<typeof protocolConnection>;
+  spies: ProtocolConnectionSpies;
 };
 
 /**
@@ -47,7 +67,10 @@ type MockConnectionMethods = {
  */
 export type MockConnection = ReturnType<typeof createConnection> & MockConnectionMethods;
 
-function protocolConnection(requests: EventEmitter, notifications: EventEmitter) {
+function protocolConnection(
+  requests: EventEmitter,
+  notifications: EventEmitter,
+): ProtocolConnectionSpies {
   return {
     dispose: vi.fn(),
     end: vi.fn(),
@@ -68,7 +91,7 @@ function protocolConnection(requests: EventEmitter, notifications: EventEmitter)
     sendProgress: vi.fn(),
     sendRequest: vi.fn(),
     trace: vi.fn().mockReturnValue(Promise.resolve()),
-  } satisfies ProtocolConnection;
+  };
 }
 
 export function mockConnection(rootUri: string): MockConnection {
@@ -83,7 +106,7 @@ export function mockConnection(rootUri: string): MockConnection {
   const spies = protocolConnection(requests, notifications);
 
   // Create a real "connection" with the fake communication channel
-  const connection = createConnection(() => spies, watchDog);
+  const connection = createConnection(() => spies as unknown as ProtocolConnection, watchDog);
 
   // Create a mock way to trigger notification in our tests
   const triggerNotification: MockConnection['sendNotification'] = async (...args: any[]) => {