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feat(eslint-plugin): add extension rule `no-duplicate-imports` #2609

merged 6 commits into from Oct 4, 2020


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@yeonjuan yeonjuan commented Sep 29, 2020

fixes #2315

I made an extension rule which distinguishes type-only import from standard import. :)

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@typescript-eslint typescript-eslint bot commented Sep 29, 2020

Thanks for the PR, @yeonjuan!

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@codecov codecov bot commented Sep 29, 2020

Codecov Report

Merging #2609 into master will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2609      +/-   ##
+ Coverage   92.82%   92.84%   +0.01%     
  Files         293      294       +1     
  Lines        9619     9657      +38     
  Branches     2697     2709      +12     
+ Hits         8929     8966      +37     
  Misses        326      326              
- Partials      364      365       +1     
Flag Coverage Δ
#unittest 92.84% <ø> (+0.01%) ⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files Coverage Δ
packages/eslint-plugin/src/configs/all.ts 100.00% <ø> (ø) 97.36% <ø> (ø)
yeonjuan added 3 commits Sep 29, 2020
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@bradzacher bradzacher left a comment

LGTM - thanks for your contribution!

if (typeImports.has(value)) {
report('exportTypeAs', node, value);
Comment on lines +86 to +88

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bradzacher Oct 4, 2020

Wait... is this really how the base rule works?

What is wrong with the code

import { T } from 'foo';
export { A } from 'foo';

This seems like it's much better than

import { T, A } from 'foo';
export { A };

Because the latter code defines a local variable for no reason.

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yeonjuan Oct 4, 2020
Author Contributor

@bradzacher right! This rule seems just focus on duplicate module sources.🤣

@bradzacher bradzacher merged commit 498f397 into typescript-eslint:master Oct 4, 2020
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@richard-viney richard-viney commented Oct 6, 2020

I've run into some false positives with this rule when used with import type.

Specifically, the following code triggers this new rule:

import type Foo from "my-module"
import type { Bar } from "my-module"

But it is not actually possible to write

import type Foo, { Bar } from "my-module"

because that results in the TypeScript error

A type-only import can specify a default import or named bindings, but not both.ts(1363)

This rule may need some additional logic to handle this case.

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@bradzacher bradzacher commented Oct 6, 2020

please file a new issue.

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@richard-viney richard-viney commented Oct 6, 2020

New issue is here: #2636

parser: '@typescript-eslint/parser',
});'no-dupe-class-members', rule, {

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ginger-kang Oct 6, 2020

Hi :)
Isn't this rule id should be no-duplicate-imports, not no-dupe-class-members?

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4 participants