jestjs/jest

[Bug]: createMockFromModule not mocking class correctly

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#14,178 opened on Jun 2, 2023

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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

Research direction
Reproduce the issue by following the steps in the description. Locate the `createMockFromModule` implementation in the Jest source code (likely in packages/jest runtime or packages/jest mock). Trace how it handles class exports. Understand why properties and getters are not mocked. Consider adding support for mocking class properties including getters.
Tech stack
typescriptjavascript
Domain
testing
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.
1-2 days
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
JavaScriptGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65