Apex: Unit test results show only 2,000 results when more results exist

Summary

When an org has over 2,000 local test methods, and all local tests are run, only 2,000 results will be included in the test output file.

Steps To Reproduce:

Repository to reproduce: dreamhouse-lwc-unit-test-issue.zip

1. Run the bin/install-scratch.sh script
2. Run sfdx force:apex:test:run --resultformat human --wait 60 --outputdir ./tests/apex

Expected result

The results file in /tests/apex will contain 2157 results

Actual result

The results file in /tests/apex will contain 2000 results

Additional information

The sample project is the vanilla lwc dreamhouse project with the addition of one test class that contains over 2k test methods.

Navigating to the test execution history in the Setup UI in the scratch org will show the correct number of test results:

We believe this issue started with the 51.7.1 (April 8, 2021) - CLI 7.96.1 release

SFDX CLI Version(to find the version of the CLI engine run sfdx --version):

7.99.0

SFDX plugin Version(to find the version of the CLI plugin run sfdx plugins --core)

51.12.0

OS and version:

macOS 10.15.7 (19H524)

[brpowell]

This was also addressed in v51.15.0 of the extensions

[AnanyaJha]

Hi @jwalke! This issue has been addressed by release v0.2.1 of the Apex plugin. To access these changes, please run sfdx plugins:install apex@0.2.1. The plugin version can be verified by running sfdx plugins.