fix: don't escape "\" in diff view (#2430)

Author: poyoho

packages/vitest/src/integrations/chai/jest-matcher-utils.ts

@@ -109,6 +109,7 @@ export function stringify(object: unknown, maxDepth = 10, options?: PrettyFormat
   try {
     result = prettyFormat(object, {
       maxDepth,
+      escapeString: false,
       // min: true,
       plugins: PLUGINS,
       ...options,
@@ -118,6 +119,7 @@ export function stringify(object: unknown, maxDepth = 10, options?: PrettyFormat
     result = prettyFormat(object, {
       callToJSON: false,
       maxDepth,
+      escapeString: false,
       // min: true,
       plugins: PLUGINS,
       ...options,

test/core/test/basic.test.ts

@@ -58,3 +58,8 @@ it.fails('deprecated done callback', (done) => {
   // @ts-expect-error deprecated done callback is not typed
   done()
 })
+
+test('escaping', () => {
+  expect(['\\123']).toEqual(['\\123'])
+  expect('\\123').toEqual('\\123')
+})