enzymejs/enzyme

Enzyme's `React.lazy` support is reducing coverage

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#2238 opened on Sep 13, 2019

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help wanted

Description

Current behavior

Screen Shot 2019-08-14 at 11 49 32 AM

Expected behavior

React.lazy line is covered.

Reference: https://github.com/airbnb/enzyme/issues/1917#issuecomment-521326956

@ljharb created a new issue for you as suggested.

Your environment

API

  • shallow
  • mount
  • render

Version

library version
enzyme 3.10.0
react 16.9.x
react-dom 16.9.x
react-test-renderer 16.9.x
adapter (below)

Adapter

  • enzyme-adapter-react-16

Contributor guide

Tech stack
javascriptreactjest
Domain
testingfrontend
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.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
ReactEnzymeReact.lazytest coverage
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
The issue reports that Enzyme's shallow rendering does not cover React.lazy components, reducing code coverage. Refer to the linked comment in issue #1917 for context. Investigate the shallow rendering adapter for React 16 (packages/enzyme adapter react 16) and identify where React.lazy should be handled. Write a test to ensure the lazy loaded component is recognized and covered.