task-4: extractErrorMessage 命名导出并覆盖 error/message/msg 三字段（空白跳过、优先级 error>message>msg）

frontend-vue/tests/extract-error.test.ts

@@ -0,0 +1,58 @@
+import { test } from 'node:test'
+import assert from 'node:assert/strict'
+import { AxiosError } from 'axios'
+import { extractErrorMessage } from '../src/shared/api/http.ts'
+
+function makeAxiosError(status: number, data: unknown) {
+  return new AxiosError('Request failed with status code ' + status, String(status), undefined, undefined, {
+    status,
+    data,
+    statusText: '',
+    headers: {},
+    config: {} as never,
+  })
+}
+
+test('test_extract_error_field', () => {
+  const error = makeAxiosError(400, { error: '字段校验失败' })
+  assert.equal(extractErrorMessage(error), '字段校验失败')
+})
+
+test('test_extract_message_field', () => {
+  const error = makeAxiosError(500, { message: '服务器内部错误' })
+  assert.equal(extractErrorMessage(error), '服务器内部错误')
+})
+
+test('test_extract_msg_field', () => {
+  const error = makeAxiosError(400, { msg: '任务已存在' })
+  assert.equal(extractErrorMessage(error), '任务已存在')
+})
+
+test('test_extract_error_precedence', () => {
+  const error = makeAxiosError(400, { error: 'e1', message: 'm1', msg: 'm2' })
+  assert.equal(extractErrorMessage(error), 'e1', 'error 应优先')
+
+  const noError = makeAxiosError(400, { message: 'm1', msg: 'm2' })
+  assert.equal(extractErrorMessage(noError), 'm1', '无 error 时 message 优先于 msg')
+})
+
+test('test_extract_string_body', () => {
+  const error = makeAxiosError(502, 'Bad Gateway 网关错误')
+  assert.equal(extractErrorMessage(error), 'Bad Gateway 网关错误')
+})
+
+test('test_extract_fallback_message', () => {
+  const error = makeAxiosError(500, {})
+  assert.equal(extractErrorMessage(error), 'Request failed with status code 500')
+})
+
+test('test_extract_axios_non_error', () => {
+  assert.equal(extractErrorMessage(new Error('普通错误')), '普通错误')
+  assert.equal(extractErrorMessage('纯字符串'), '请求失败')
+  assert.equal(extractErrorMessage(undefined), '请求失败')
+})
+
+test('test_extract_blank_values_skipped', () => {
+  const error = makeAxiosError(400, { error: '  ', message: '', msg: '真实原因' })
+  assert.equal(extractErrorMessage(error), '真实原因', '空白 error/message 应跳过，回退 msg')
+})