cypress/grep throws error when used together with .only

[haipinggong]

Current behavior

1. Install @cypress/grep plugin.
2. Configure cypress to use @cypress/grep plugin to filter out cases.
3. Create some cases with different tags.
4. Add .only for one of the case.
5. Run the spec file with --env grepTags=tag

Cypress throws an error when I add .only in one of the test cases and use --env grepTags=@tag2 filter out the cases.

Desired behavior

Cypress can filter out the cases based on grepTags env variable and run the cases with .only based on the filtered out test case list.

Test code to reproduce

https://github.com/haipinggong/cypress-test-tiny/tree/grep-only-bug

1. Install the dependencies: npm install
2. Filter out the cases with tag: @tag2 and run the test by using command: npx cypress run --env grepTags=@tag2

Expected result:
Only the test with name: "tag2 should be run" is run.

Actual result:

Cypress Version

11.2.0

Node version

v16.15.0

Operating System

Windows 11

Debug Logs

No response

Other

No response

[avramd]

FWIW, we are experiencing a related behavior:

• When running the above scenario from the command line (rather than in the Cypress IDE)
• and we put .only on a test with a tag @tag
• and specify CYPRESS_grepTags='@tag'
• cypress correctly filters out all other tests
• but then it skips (treats as pending) the one .only test that does have the tag on it.

software_updates_api.cy.js:
      it.only('uploads update file', { tags: '@appRestart' }, () => {

CYPRESS_DEVICE_ID=voltserv-6da4 npm test -- --env grepTags='@appRestart' --spec software_updates_api.cy.js
[...]
       Spec                                              Tests  Passing  Failing  Pending  Skipped  
  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ ✔  software_updates_api.cy.js                23ms        1        -        -        1        - │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘
    ✔  All specs passed!                         23ms        1        -        -        1        -  

We are running @cypress/grep v4.0.1.