Docs: context migration suggestions fail on earlier v8 versions

[MikeMcC399]

Docs page(s)

• Preparing your custom rules for ESLint v9.0.0 > From context to SourceCode which is linked to by

• Migrate to v9.x > Removed multiple context methods

At least the following call transitions are problematic where the API call was not available on earlier ESLint v8.x releases

• context.getScope() => SourceCode#getScope(node) added in ESLint v8.37.0
• context.getAncestors() => SourceCode#getAncestors(node) added in ESLint v8.38.0

Other calls added around the same time are probably also affected.

What documentation issue do you want to solve?

Code examples using
const { sourceCode } = context; cause an error running in Jest for ESLint < v8.37.0.

TypeError: Cannot read properties of undefined (reading 'getScope')

What do you think is the correct solution?

Please check if this should be changed to
const { sourceCode = {} } = context;

Participation

• I am willing to submit a pull request for this change.

Additional comments

Steps to reproduce

Ubuntu 22.04.4 LTS, Node.js 20.12.2 using ESLint 8.57.0 as base vesion.

Original state

git clone https://github.com/MikeMcC399/eslint-plugin-cypress
cd eslint-plugin-cypress
git switch show/api-deprecation
npm ci
npx jest tests/lib/rules/no-unnecessary-waiting.js --silent

Note deprecation warning

$ npx jest tests/lib/rules/no-unnecessary-waiting.js --silent
(node:24892) DeprecationWarning: "no-unnecessary-waiting" rule is using `context.getScope()`, which is deprecated and will be removed in ESLint v9. Please use `sourceCode.getScope()` instead.
(Use `node --trace-deprecation ...` to show where the warning was created)
PASS tests/lib/rules/no-unnecessary-waiting.js

Recommended update

Using recommended code from blog Preparing your custom rules for ESLint v9.0.0 > From context to SourceCode

git switch show/convert-to-sourcecode-Rev1
npm install [email protected]
npx jest tests/lib/rules/no-unnecessary-waiting.js

Note failure (log truncated):

$ npx jest tests/lib/rules/no-unnecessary-waiting.js --silent
FAIL tests/lib/rules/no-unnecessary-waiting.js
  ● no-unnecessary-waiting › valid › cy.wait("@someRequest")

    TypeError: Cannot read properties of undefined (reading 'getScope')
    Occurred while linting <input>:1
    Rule: "no-unnecessary-waiting"

      20 |       CallExpression (node) {
      21 |         if (isCallingCyWait(node)) {
    > 22 |           const scope = sourceCode.getScope
         |                                    ^
      23 |             ? sourceCode.getScope(node)
      24 |             : context.getScope()
      25 |
...

Modified update

Use suggested change const { sourceCode = {} } = context; in branch show/convert-to-sourcecode-Rev2
Continue to use [email protected]

git switch show/convert-to-sourcecode-Rev2
npx jest tests/lib/rules/no-unnecessary-waiting.js --silent

Note success with no deprecation message:

$ npx jest tests/lib/rules/no-unnecessary-waiting.js --silent
PASS tests/lib/rules/no-unnecessary-waiting.js

Revert to [email protected]

git restore .
npm ci
npx jest tests/lib/rules/no-unnecessary-waiting.js --silent

Note also success with no deprecation message.

[nzakas]

Thanks. I'm working on this.

[MikeMcC399]

@nzakas

Many thanks for the update to the blog Preparing your custom rules for ESLint v9.0.0 > From context to SourceCode!

I ran into a snag when implementing this, since the repo I'm updating had the following in its config:

  "parserOptions": {
    "ecmaVersion": 2018
  }

I needed to update to "ecmaVersion": 2020 because the Nullish coalescing operator (??) was not available in previous versions.

[MikeMcC399]

@nzakas

Thanks once again for the assistance!

cypress-io/[email protected] has successfully used your new recommendations!