Warning: Illegal string offset 'failOnRisky' and 'failOnWarning'

[df-mreidel]

Q	A
PHPUnit version	6.3.0
PHP version	7.1.8
Installation Method	Composer

When running a single files, everything runs smooth and without any notices. If I run vendor/bin/phpunit tests/integration however, I'm getting

PHPUnit 6.3.0 by Sebastian Bergmann and contributors.

...........................................                       43 / 43 (100%)

Time: 1.41 seconds, Memory: 6.00MB

OK (43 tests, 75 assertions)

Warning: Illegal string offset 'failOnRisky' in /usr/local/xxx/vendor/phpunit/phpunit/src/TextUI/TestRunner.php on line 669

Warning: Illegal string offset 'failOnWarning' in /usr/local/xxx/vendor/phpunit/phpunit/src/TextUI/TestRunner.php on line 673

It happens even after a clean install, without any config files. I tried to fix the error by supplying the corresponding command line parameters, but that didn't work. Neither did creating a config file:

<?xml version="1.0" encoding="utf-8" ?>
<phpunit backupGlobals="true"
         backupStaticAttributes="true"
         bootstrap="tests/integration/bootstrap.ini"
         failOnWarning="true"
         failOnRisky="true"
         timeoutForSmallTests="1"
         timeoutForMediumTests="10"
         timeoutForLargeTests="60"
         verbose="false">
  <testsuites>
    <testsuite name="IntegrationTests">
      <directory suffix="php" phpVersion="7.1.0" phpVersionOperator=">=">tests/integration</directory>
    </testsuite>
  </testsuites>
</phpunit>

[df-mreidel]

Adding to the above, I wanted to know what's actually inside $arguments and here it is:

string(1446) "{"listGroups": false, "listSuites": false, "loader": null, "useDefaultConfiguration": true, "loadedExtensions": {}, "notLoadedExtensions": {}, "testSuffixes": ["Test.php", ".phpt"], "configuration": Object PHPUnit\Util\Configuration, "debug": false, "filter": false, "listeners": {}, "backupGlobals": true, "backupStaticAttributes": true, "timeoutForSmallTests": 1, "timeoutForMediumTests": 10, "timeoutForLargeTests": 60, "verbose": true, "testdoxGroups": {}, "testdoxExcludeGroups": {}, "addUncoveredFilesFromWhitelist": true, "beStrictAboutChangesToGlobalState": null, "beStrictAboutResourceUsageDuringSmallTests": false, "cacheTokens": false, "colors": "never", "columns": 80, "convertDeprecationsToExceptions": true, "convertErrorsToExceptions": true, "convertNoticesToExceptions": true, "convertWarningsToExceptions": true, "crap4jThreshold": 30, "disallowTestOutput": false, "disallowTodoAnnotatedTests": false, "enforceTimeLimit": false, "excludeGroups": {}, "failOnRisky": false, "failOnWarning": false, "groups": {}, "processIsolation": false, "processUncoveredFilesFromWhitelist": false, "registerMockObjectsFromTestArgumentsRecursively": false, "repeat": false, "reportHighLowerBound": 90, "reportLowUpperBound": 50, "reportUselessTests": true, "reverseList": false, "stopOnError": false, "stopOnFailure": false, "stopOnIncomplete": false, "stopOnRisky": false, "stopOnSkipped": false, "stopOnWarning": false, "strictCoverage": false}"

I doubt that it's supposed to be JSON instead of a PHP array...