vuejs / vuejs/test-utils

Bug: Optional props are typed as `| undefined`

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#2,256 2 comments 0 reactions 0 assignees View on GitHub

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bug
Dominant language
TypeScript
Stars
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Forks
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Avg merge
1d 9h
Merged PRs (30d)
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Description

Describe the bug
When using the .props() method on a VueWrapper for a prop which is not required but has a default value the returned type includes undefined.

To Reproduce
https://github.com/DesselBane/test-utils-reproduction/blob/master/src/components/foo.spec.ts

Expected behavior
I would argue that the type should not include undefined since it has a default value and this default value is returned at runtime.

Related information:
This happened on an update from v2.4.1 to v2.4.2, most likely somewhere in this PR: https://github.com/vuejs/test-utils/pull/2137 (but I'm not sure)

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the linked reproduction in src/components/foo.spec.ts and compare the behavior between versions 2.4.1 and 2.4.2. Review PR 2137 and the surrounding prop type definitions; done means VueWrapper.props() no longer includes undefined for optional props with runtime defaults, while preserving correct typing for other props.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
frontend, testing
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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