jest.mock does not mock an ES module without Babel

<!-- Love Jest? Please consider supporting our collective: 👉 https://opencollective.com/jest/donate --> ## 🐛 Bug Report <!-- A clear and concise description of what the bug is. --> In an ES module Node project, with no Babel, `jest.mock` works when the mocked module is a `node_modules` package that exports CommonJS, but it isn't working for me mocking an ES module exported from a file in the same project. (It's possible that an NPM package that only exports ES modules has the same issue. I didn't try that case.) ## To Reproduce Steps to reproduce the behavior: Click Run in the repl, or here's a simple example: ```js // main.js import secondary from "./secondary.js"; export default function main() { return secondary(); } // secondary.js export default function secondary() { return true; } // test.js import { jest } from "@jest/globals"; jest.mock("./secondary.js"); let main; let secondary; beforeAll(async () => { ({ default: main } = await import("./main.js")); ({ default: secondary } = await import("./secondary.js")); }); test("works", () => { secondary.mockReturnValueOnce(false); // TypeError: Cannot read property 'mockReturnValueOnce' of undefined expect(main()).toBe(false); }); ``` ## Expected behavior <!-- A clear and concise description of what you expected to happen. --> `jest.mock(filename)` should mock the exports from `filename` when the test file and the Node project are both ES modules (`type: "module"`) ## Link to repl or repo (hig

Posted by aldeed on May 11, 2020, 10:16 PM

Tags

• github (Other)

Related issues

• struct's lifetime requirements can be bypassed via covariant field assignment
• Proposal to Reorganize the Moderation Team and Review Moderation Policies
• Progressive FPS degradation appears to be related to dota2.com — blocking the domain prevents the performance loss
• proposal: container/...: generic collection types
• Better Custom Endpoint BYOK
• A concrete policy for backward compatibility until Godot 5.0