fix: use toJSON for error serialization (#5526)

packages/utils/src/error.ts

@@ -44,6 +44,8 @@ export function serializeError(val: any, seen = new WeakMap()): any {
     return val.tagName
   if (typeof val.asymmetricMatch === 'function')
     return `${val.toString()} ${format(val.sample)}`
+  if (typeof val.toJSON === 'function')
+    return val.toJSON()
 
   if (seen.has(val))
     return seen.get(val)

test/reporters/fixtures/error-to-json.test.ts

@@ -0,0 +1,5 @@
+import { test } from "vitest";
+
+test("error serialization with toJSON", () => {
+  throw Object.assign(new Error("hello"), { date: new Date(0) })
+})

test/reporters/tests/__snapshots__/html.test.ts.snap

@@ -45,7 +45,6 @@ exports[`html reporter > resolves to "failing" status for test file "json-fail"
             "errors": [
               {
                 "actual": "2",
-                "constructor": "Function<AssertionError>",
                 "diff": "- Expected
 + Received
 
@@ -59,8 +58,6 @@ exports[`html reporter > resolves to "failing" status for test file "json-fail"
                 "showDiff": true,
                 "stack": "AssertionError: expected 2 to deeply equal 1",
                 "stackStr": "AssertionError: expected 2 to deeply equal 1",
-                "toJSON": "Function<anonymous>",
-                "toString": "Function<toString>",
               },
             ],
             "hooks": {

test/reporters/tests/error-to-json.test.ts

@@ -0,0 +1,7 @@
+import { expect, test } from 'vitest'
+import { runVitest } from '../../test-utils'
+
+test('should print logs correctly', async () => {
+  const result = await runVitest({ root: './fixtures' }, ['error-to-json.test.ts'])
+  expect(result.stderr).toContain(`Serialized Error: { date: '1970-01-01T00:00:00.000Z' }`)
+})