fix(linter/no-standalone-expect): allows expect in wrapper functions passed to test blocks

[Copilot]

The no-standalone-expect rule incorrectly flagged expect calls inside arrow functions passed to wrapper functions (e.g., Angular's fakeAsync()) when those wrapper functions were arguments to test blocks.

// Previously failed, now passes
it('test', fakeAsync(() => {
  expect(true).toBeTruthy();
}));

// Still correctly fails
describe('suite', () => {
  fakeAsync(() => {
    expect(true).toBeTruthy();
  });
});

Changes

• Modified is_var_declarator_or_test_block: When a CallExpression is not a test block, recursively check if its parent CallExpression is one. This handles cases where wrapper functions are nested as arguments to test blocks.

• Added test coverage: Test cases for both jest and vitest plugins covering the fakeAsync pattern and multi-level wrapper nesting.

The fix aligns oxlint's behavior with eslint-plugin-jest, which uses a stack-based approach that implicitly allows wrapper functions as arguments to test blocks.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>linter: behavior of no-standalone-expect rule differs between eslint and oxlint</issue_title>
<issue_description>### What version of Oxlint are you using?

1.35.0

What command did you run?

oxlint

What does your .oxlintrc.json config file look like?

{
  "plugins": ["jest", "vitest"],
  "rules": {
    "vitest/no-standalone-expect": "error"
  }
}

What happened?

A similar situation occurs in vitest/no-standalone-expect and jest/no-standalone-expect

I use the no-standalone-expect rule for tests inside Angular projects. The key feature of these tests is that they allow the use of built-in Angular testing capabilities. For example, the fakeAsync function from the @angular/core/testing library. It allows you to stabilize asynchronous tests.

But I ran into a problem that the default behavior of the no-standalone-expect rule in Eslint and Oxlint is different.

Eslint config:

import {defineConfig} from 'eslint/config'
import vitest from '@vitest/eslint-plugin'

export default defineConfig({
  plugins: {
    vitest,
  },
  rules: {
    'vitest/no-standalone-expect': 'error'
  },
})

@vitest/eslint-plugin: 1.6.4
eslint: 9.39.2

I have a test written in my code like this:

import {fakeAsync} from '@angular/core/testing';

describe('App', () => {
  it('should create the app', fakeAsync(() => {
    expect(true).toBeTruthy();
  }));
});

I'm getting an error in oxlint:

  × eslint-plugin-jest(no-standalone-expect): `expect` must be inside of a test block.
   ╭─[file:///~/oxlint-jest-issue/src/app/app.spec.ts:5:5]
 4 │   it('should create the app', fakeAsync(() => {
 5 │     expect(true).toBeTruthy();
   ·     ──────
 6 │   }));
   ╰────
  help: Did you forget to wrap `expect` in a `test` or `it` block?

This is correct from the logic point of view of the rule, but the main problem is that the original eslint rule does not throw an error for this case. I know about additionalTestBlockFunctions, but I assume (I could be wrong) that oxlint rules should perfectly match eslint rules in behavior. Or at least have some documentation indicating that the behavior in this rule may differ.

You can visually check the behavior in this repository - https://github.com/lld4n/oxlint-vitest-issue</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes linter: behavior of no-standalone-expect rule differs between eslint and oxlint #17426

---

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[Copilot]

Pull request overview

This PR fixes the no-standalone-expect rule to allow expect calls inside arrow functions passed to wrapper functions (e.g., Angular's fakeAsync()) when those wrapper functions are arguments to test blocks. This aligns oxlint's behavior with eslint-plugin-jest, which uses a stack-based approach that implicitly handles this pattern.

Key Changes

• Modified is_var_declarator_or_test_block function to recursively check parent CallExpressions when a CallExpression is not itself a test block
• Added test coverage for the fakeAsync pattern and basic wrapper function nesting for both jest and vitest plugins

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
crates/oxc_linter/src/rules/jest/no_standalone_expect/mod.rs	Added recursive parent checking logic to handle wrapper functions passed as arguments to test blocks
crates/oxc_linter/src/rules/jest/no_standalone_expect/tests/jest.rs	Added passing test cases for fakeAsync wrapper and generic wrapper functions, plus one failing test case for wrappers not in test blocks
crates/oxc_linter/src/rules/jest/no_standalone_expect/tests/vitest.rs	Added passing test cases for fakeAsync wrapper and generic wrapper functions for vitest plugin
crates/oxc_linter/src/snapshots/jest_no_standalone_expect.snap	Updated snapshot to include expected failure for wrapper function not passed to test block
crates/oxc_linter/src/snapshots/eslint_object_shorthand.snap	Unrelated file - Contains snapshots for object-shorthand rule, not related to this PR

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[codspeed-hq]

CodSpeed Performance Report

Merging #17427 will not alter performance

_{Comparing copilot/fix-no-standalone-expect-rule (c1ef270) with main (dab232f)}

Summary

✅ 4 untouched
⏩ 41 skipped¹

Footnotes

1. 41 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩