jestjs/jest

[Bug]: createMockFromModule not mocking class correctly

Open

#14178 opened on Jun 2, 2023

View on GitHub
 (9 comments) (0 reactions) (0 assignees)TypeScript (45,361 stars) (6,653 forks)batch import
:bug: BugHelp WantedPinned

Description

Version

29.5.0

Steps to reproduce

  1. Clone my repo at https://github.com/dominiktopp/jestCreateMockFromModuleIssue
  2. npm install
  3. npm test
  4. tests will fail

Expected behavior

I expect the test cases to succeed.

Actual behavior

Tests are failing because jest.createMockFromModule only mocks constructor and functions for classes but no other properties (also no getters). The example for jest.createMockFromModule does not mock an exported class but an instance of a class: class: new (class Bar {...})()

Additional context

No response

Environment

System:
  OS: Windows 10 10.0.19045
  CPU: (12) x64 Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz
  Memory: 10.67 GB / 31.76 GB
Binaries:
  Node: 16.15.0 - C:\Program Files\nodejs\node.EXE
  npm: 8.5.5 - C:\Program Files\nodejs\npm.CMD

Contributor guide

Tech stack
typescriptjavascriptnodejs
Domain
testingdeveloper experience
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Understanding of Jest mock functionsBasic TypeScript class syntax
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Review the issue's reproduction repo at https://github.com/dominiktopp/jestCreateMockFromModuleIssue. Examine the exported class to see which properties are not mocked. Look at the `jest.createMockFromModule` implementation in `packages/jest runtime/src/index.ts` and related files. Check comments for additional context. The fix likely involves ensuring class instance properties and getters are included in the mock.