mock ES Imports directly

Author: JaneJeon

dns.js

@@ -1,4 +1,4 @@
-import { lookup as nativeCallbackLookup } from './dns.js' // HACK WARNING
+import { lookup as nativeCallbackLookup } from 'dns'
 import { promisify } from 'util'
 import got from 'got'
 import ip from 'ipaddr.js'

esm-resolver.cjs

@@ -1,6 +1,13 @@
-import { expect, describe, it } from '@jest/globals'
+import { expect, describe, it, jest } from '@jest/globals'
 import nock from 'nock'
-import { gotSsrf } from './index.js'
+
+// We can directly mock the "import { lookup } from 'dns'" call in index.js with jest.
+const mockDnsModule = await import('./__mocks__/dns.js')
+jest.unstable_mockModule('dns', () => mockDnsModule)
+
+// However, it does mean that we need to do a dynamic import to make sure we load the mocked import.
+// See: https://jestjs.io/docs/ecmascript-modules#module-mocking-in-esm
+const { gotSsrf } = await import('./index.js')
 
 nock.disableNetConnect()
 

index.js

@@ -3,8 +3,5 @@ process.env.JEST_JUNIT_OUTPUT_DIR = 'reports/jest'
 module.exports = {
   reporters: ['default', 'jest-junit'],
   errorOnDeprecated: true,
-  notify: true,
-  testEnvironment: 'jest-environment-node',
-  transform: {},
-  resolver: '<rootDir>/esm-resolver.cjs'
+  notify: true
 }

index.test.js

@@ -25,10 +25,9 @@
   "devDependencies": {
     "@janejeon/eslint-config": "3.0.0-3",
     "@janejeon/prettier-config": "^1.1.0",
-    "enhanced-resolve": "^5.8.3",
     "husky": "^8.0.1",
-    "jest": "^27.2.1",
-    "jest-junit": "^14.0.0",
+    "jest": "^29.5.0",
+    "jest-junit": "^16.0.0",
     "lint-staged": "13.0.3",
     "nock": "^13.1.3",
     "node-notifier": "^10.0.0",