Repo: rule-tester: Can I use the output of the snapshot test rules? #7449

u3u · 2023-08-10T11:12:19Z

Motivation

When a rule contains an auto-fix program, I want to test if the output of the fix meets my expectations. The simplest way is to use snapshot testing and check if the snapshot matches the expected result.

However, now I need to manually maintain strict formatting for indentation, spaces, and other formatting-related outputs.

I also need to use dedent to ensure consistent indentation. This is too troublesome.

If I want to optimize the auto-fixing process, I also need to manually synchronize the output of the tests (sometimes it may be just one extra or missing space, which should not matter because it will eventually be formatted by Prettier).

Example

https://github.com/u3u/eslint-plugin-arrow-return-style/blob/bfa3cc81f15526aa76fe1b043d0a394ffe3be2ba/src/rules/arrow-return-style.test.ts

import { RuleTester } from '@typescript-eslint/rule-tester';
import dedent from 'dedent';
import { afterAll, describe, it } from 'vitest';
import { arrowReturnStyleRule, RULE_NAME } from './arrow-return-style';

RuleTester.afterAll = afterAll;
RuleTester.describe = describe;
RuleTester.it = it;

const ruleTester = new RuleTester({
  parser: '@typescript-eslint/parser',

  parserOptions: {
    ecmaFeatures: { jsx: true },
  },
});

ruleTester.run(RULE_NAME, arrowReturnStyleRule, {
  invalid: [
    {
      code: dedent`
        const delay = () =>
          new Promise((resolve) => {
            setTimeout(resolve, 1000)
          })
      `,

      errors: [{ messageId: 'useExplicitReturn' }],

      output: dedent`
        const delay = () =>
          { return new Promise((resolve) => {
            setTimeout(resolve, 1000)
          }) }
      `,
    },

    {
      code: dedent`
        const foo = () => {
          return 'foo'
        }
      `,

      errors: [{ messageId: 'useImplicitReturn' }],

      output: dedent`
        const foo = () => 
          'foo'\n
      `,
    },

    {
      code: dedent`
        Array.from({ length: 10 }).map((_, i) => {
          return i + 1
        })
      `,

      errors: [{ messageId: 'useImplicitReturn' }],

      output: dedent`
        Array.from({ length: 10 }).map((_, i) => 
          i + 1
        )
      `,
    },

    {
      code: dedent`
        const obj = () => {
          return { name: '' }
        }
      `,

      errors: [{ messageId: 'useImplicitReturn' }],

      output: dedent`
        const obj = () => 
          ({ name: '' })\n
      `,
    },

    {
      code: dedent`
        const data = () => ({
          name: ''
        })
      `,

      errors: [{ messageId: 'useExplicitReturn' }],

      output: dedent`
        const data = () => { return {
          name: ''
        } }
      `,
    },

    {
      code: 'export const defineConfig = <T extends Linter.Config>(config: T) => config',
      errors: [{ messageId: 'useExplicitReturn' }],
      output: 'export const defineConfig = <T extends Linter.Config>(config: T) => { return config }',
    },

    {
      code: 'const Div = () => <><div /></>',
      errors: [{ messageId: 'useExplicitReturn' }],
      options: [{ jsxAlwaysUseExplicitReturn: true }],
      output: 'const Div = () => { return <><div /></> }',
    },

    {
      code: dedent`
        const FC = () =>
          <Foo
          // d=""
          z
          // test={{}}
          data-ignore=""
          bar={[]}
        />
      `,

      errors: [{ messageId: 'useExplicitReturn' }],

      output: dedent`
        const FC = () =>
          { return <Foo
          // d=""
          z
          // test={{}}
          data-ignore=""
          bar={[]}
        /> }
      `,
    },

    {
      code: dedent`
        export const createRule = ESLintUtils.RuleCreator(
          (rule) => \`https://github.com/u3u/eslint-plugin-arrow-return-style/tree/v\${version}/docs/rules/\${rule}.md\`
        )
      `,

      errors: [{ messageId: 'useExplicitReturn' }],

      output: dedent`
        export const createRule = ESLintUtils.RuleCreator(
          (rule) => { return \`https://github.com/u3u/eslint-plugin-arrow-return-style/tree/v\${version}/docs/rules/\${rule}.md\` }
        )
      `,
    },

    {
      code: 'const render = () => (<div />)',
      errors: [{ messageId: 'useExplicitReturn' }],
      options: [{ jsxAlwaysUseExplicitReturn: true }],
      output: 'const render = () => { return <div /> }',
    },

    {
      code: dedent`
        const fn = () =>
          /* block comment */
          1
      `,

      errors: [{ messageId: 'useExplicitReturn' }],

      output: dedent`
        const fn = () => {
          /* block comment */
          return 1
        }
      `,
    },

    {
      code: dedent`
        const test = () =>
          // line comment
          ({ name: 'test' })
      `,

      errors: [{ messageId: 'useExplicitReturn' }],

      output: dedent`
        const test = () => {
          // line comment
          return { name: 'test' }
        }
      `,
    },
  ],

  valid: [
    'const t = () => Date.now()',
    'const fn = () => { return }',

    'Array.from({ length: 10 }).map((_, i) => i + 1)',

    {
      code: 'const Div = () => <><div /></>',
      options: [{ jsxAlwaysUseExplicitReturn: false }],
    },

    dedent`
      const bar = () => {
        // line comment
        return 'bar'
      }
    `,

    dedent`
      const fn = async () => {
        await delay(300)
        return 'fn'
      }
    `,

    dedent`
      export const getUser = async () => {
        return {}
      }
    `,
  ],
});

The text was updated successfully, but these errors were encountered:

bradzacher · 2023-08-10T12:48:56Z

No, you currently cannot.
We are investigating this though - see #6499 and pr #6994

u3u added repo maintenance things to do with maintenance of the repo, and not with code/docs triage Waiting for team members to take a look labels Aug 10, 2023

bradzacher closed this as not planned Won't fix, can't repro, duplicate, stale Aug 10, 2023

bradzacher added question Questions! (i.e. not a bug / enhancment / documentation) and removed triage Waiting for team members to take a look repo maintenance things to do with maintenance of the repo, and not with code/docs labels Aug 10, 2023

github-actions bot locked as resolved and limited conversation to collaborators Aug 18, 2023

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Repo: rule-tester: Can I use the output of the snapshot test rules? #7449

Repo: rule-tester: Can I use the output of the snapshot test rules? #7449

Repo: rule-tester: Can I use the output of the snapshot test rules? #7449

Repo: rule-tester: Can I use the output of the snapshot test rules? #7449

Comments

Motivation

Example