import-js/eslint-plugin-import

Inconsistent import/prefer-default-export with Flow type

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#1,164 opened on Aug 23, 2018

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bugflowhelp wanted

Description

The following file is generating a warning that default export should be used.

Prefer default export. (import/prefer-default-export)

/* @flow */

export type AnswerState = {
  foo: string
}

export const answer: AnswerState = {
  foo: ''
}

This one however, is not generating any errors or warnings.

/* @flow */

- export type AnswerState = {
+ type AnswerState = {
  foo: string
}

export const answer: AnswerState = {
  foo: ''
}

+ export type { AnswerState }

Originally posted in #484.

Contributor guide

Tech stack
javascript
Domain
toolingdeveloper 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.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
ESLint rule developmentFlow type syntax
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Look at the source code of the `prefer default export` rule (likely `src/rules/prefer default export.js`). Understand how it detects named exports versus default exports. The bug is that when a type is defined and exported together with a const, the rule flags it, but when the type is exported separately, it doesn't. The fix might involve checking if the export is a type export and handling that case. Also, review the existing test file for this rule to add a test case for the Flow type scenario.