Respect nested only tests

[jwerre]

Clear and concise description of the problem

Currently if you have an test.only inside a description.only all the tests under the description run. For example:

import { describe, it, expect } from 'vitest';

describe('My Component', () => {
	describe.only('Only run this suite of tests', () => {
		test.only('should be the only test that runs', () => {
			expect(true).toBe(true);
		});

		test('should not run because the previous test has an only', () => {
			throw new Error('This test should not run');
		});
	});

	describe('This suite of tests should never run and, correctly, do not', () => {
		test('...', () => {});
		test('...', () => {});
		test('...', () => {});
	});
});

Suggested solution

Tests with only should be the only test to run. This is the way Mocha works and is very useful when developing and debugging complex test suites.

Alternative

No response

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[Ujjwaljain16]

Issue Analysis
I can confirm this issue. Currently, when [test.only] is nested inside [describe.only] all tests within the [describe.only] block run instead of respecting the nested modifier.

Current Behavior:

Expected Behavior :

Root Cause
The issue is in [collect.ts] in the [interpretTaskModes] function. When processing tasks in "only mode", the logic currently marks all tasks within a [describe.only] as included, without checking if there are more specific [test.only] modifiers within that suite.

This makes every task in a [describe.only] included, even when there's a sibling [test.only] that should be the only one running.

Solution
The fix checks if any tasks within the current suite have [.only] modifiers. If they do, only those specific tasks should run (not all tasks in the [describe.only] This respects the nested [.only] hierarchy properly.

Testing
Created test case [test/core/test/nested-only.test.ts] to verify the fix:

Before fix: ❌ Test fails (both tests run)
After fix: ✅ Test passes (only [test.only] runs)

Also verified existing test suite [only.test.ts] still passes to ensure no regression.

Working on a PR now!

[Ujjwaljain16]

@sheremet-va can i get reviews on the pr so i can modify as per the need under yr guidance and make the issue fix and get this closed asap