E.g. https://integration.wikimedia.org/ci/job/mediawiki-quibble-composertest-php70-docker/10986/console :
01:17:02 INFO:test.run_composer_test:Running composer test ... 01:17:12 > composer minus-x 'includes/DefaultSettings.php' 'includes/auth/AbstractPasswordPrimaryAuthenticationProvider.php' 'includes/password/UserPasswordPolicy.php' 'includes/user/User.php' 'tests/phpunit/includes/auth/AbstractPasswordPrimaryAuthenticationProviderTest.php' 'tests/phpunit/includes/auth/LocalPasswordPrimaryAuthenticationProviderTest.php' 'tests/phpunit/includes/password/UserPasswordPolicyTest.php' 01:17:12 > minus-x check 'includes/DefaultSettings.php' 'includes/auth/AbstractPasswordPrimaryAuthenticationProvider.php' 'includes/password/UserPasswordPolicy.php' 'includes/user/User.php' 'tests/phpunit/includes/auth/AbstractPasswordPrimaryAuthenticationProviderTest.php' 'tests/phpunit/includes/auth/LocalPasswordPrimaryAuthenticationProviderTest.php' 'tests/phpunit/includes/password/UserPasswordPolicyTest.php' 01:17:12 01:17:12 01:17:12 Too many arguments, expected arguments "command" "path". 01:17:12 01:17:12 01:17:12 check <path> 01:17:12 01:17:12 Script minus-x check handling the minus-x event returned with error code 1 01:17:12 Script composer minus-x handling the test event returned with error code 1
Apparently some CI code calls composer test specifically on the changed files, and minus-x gets confused from the extra arguments.