Empty test case class causes error in TestDox XML logger

[djbusby]

Q	A
PHPUnit version	9.5.3
PHP version	7.3.27-1~deb10u1
Installation Method	Composer

Summary

I made an empty test case, which generally throws some error now it barfs.
No output file from PHPUnit is made either.

Current behavior & How to reproduce

Make a test case like this one:

class Crappy_Test extends \PHPUnit\Framework\TestCase
{
}

Then run PHPUnit and you'll get this output:

PHP Warning:  Invalid argument supplied for foreach() in /[redacted]/vendor/phpunit/phpunit/src/Util/TestDox/XmlResultPrinter.php on line 193
Method PHPUnit\Framework\WarningTestCase::Warning() does not exist

And running with xdebug enabled gives this

PHP Warning:  Invalid argument supplied for foreach() in /[redacted]/vendor/phpunit/phpunit/src/Util/TestDox/XmlResultPrinter.php on line 193
PHP Stack trace:
PHP   1. {main}() /[redacted]/vendor/phpunit/phpunit/phpunit:0
PHP   2. PHPUnit\TextUI\Command::main() /[redacted]/vendor/phpunit/phpunit/phpunit:61
PHP   3. PHPUnit\TextUI\Command->run() /[redacted]/vendor/phpunit/phpunit/src/TextUI/Command.php:96
PHP   4. PHPUnit\TextUI\TestRunner->run() /[redacted]/vendor/phpunit/phpunit/src/TextUI/Command.php:143
PHP   5. PHPUnit\Framework\TestSuite->run() /[redacted]/vendor/phpunit/phpunit/src/TextUI/TestRunner.php:667
PHP   6. PHPUnit\Framework\TestSuite->run() /[redacted]/vendor/phpunit/phpunit/src/Framework/TestSuite.php:677
PHP   7. PHPUnit\Framework\TestSuite->run() /[redacted]/vendor/phpunit/phpunit/src/Framework/TestSuite.php:677
PHP   8. PHPUnit\Framework\WarningTestCase->run() /[redacted]/vendor/phpunit/phpunit/src/Framework/TestSuite.php:677
PHP   9. PHPUnit\Framework\TestResult->run() /[redacted]/vendor/phpunit/phpunit/src/Framework/TestCase.php:884
PHP  10. PHPUnit\Framework\TestResult->endTest() /[redacted]/vendor/phpunit/phpunit/src/Framework/TestResult.php:971
PHP  11. PHPUnit\Util\TestDox\XmlResultPrinter->endTest() /[redacted]/vendor/phpunit/phpunit/src/Framework/TestResult.php:446
Method PHPUnit\Framework\WarningTestCase::Warning() does not exist

Expected behavior

I expected it to just emit a warning, or write a warning about the empty test case to my log file (junit logger).

If I add a function to the class, eg test_something() that is empty, then it passes through no problem and writes that this test is Risky

I think PHPUnit should not abruptly stop when a TestCase script file has zero functions that are test* types. It should tell me I'm doing it wrong in the output file, like with other Risky or Warnings.

[sebastianbergmann]

Test.php

<?php declare(strict_types=1);
use PHPUnit\Framework\TestCase;

final class Test extends TestCase
{
}

$ phpunit Test.php
PHPUnit 9.5.3-5-gaad51c070 by Sebastian Bergmann and contributors.

W                                                                   1 / 1 (100%)

Time: 00:00.019, Memory: 4.00 MB

There was 1 warning:

1) Warning
No tests found in class "Test".

WARNINGS!
Tests: 1, Assertions: 0, Warnings: 1.

$ phpunit --testdox-xml testdox.xml Test.php
PHPUnit 9.5.3-5-gaad51c070 by Sebastian Bergmann and contributors.

W                                                                   1 / 1 (100%)
Warning: foreach() argument must be of type array|object, null given in /usr/local/src/phpunit/src/Util/TestDox/XmlResultPrinter.php on line 193
Method PHPUnit\Framework\WarningTestCase::Warning() does not exist