Uncaught TypeError: Return value of PHPUnit\Framework\TestCase::getActualOutput() must be of the type string, null returned

[thedotedge]

Q	A
PHPUnit version	7.0.1
PHP version	7.1.4
Installation Method	phar

Steps to reproduce:

1. Add $this->withoutOutput(); to setUp().

Fatal error: Uncaught TypeError: Return value of PHPUnit\Framework\TestCase::getActualOutput() must be of the type string, null returned in phar:///usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar/phpunit/Framework/TestCase.php on line 415

TypeError: Return value of PHPUnit\Framework\TestCase::getActualOutput() must be of the type string, null returned in phar:///usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar/phpunit/Framework/TestCase.php on line 415

Call Stack:
    0.0322     821904   1. {main}() /usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar:0
    0.0832    8425664   2. PHPUnit\TextUI\Command::main() /usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar:573
    0.0832    8425776   3. PHPUnit\TextUI\Command->run() phar:///usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar/phpunit/TextUI/Command.php:153
    0.8894   12929976   4. PHPUnit\TextUI\TestRunner->doRun() phar:///usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar/phpunit/TextUI/Command.php:205
    0.8938   12934072   5. PHPUnit\Framework\TestSuite->run() phar:///usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar/phpunit/TextUI/TestRunner.php:508
    0.8960   12934264   6. PHPUnit\Framework\TestSuite->run() phar:///usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar/phpunit/Framework/TestSuite.php:761
    1.6258   18208744   7. PHPUnit\Framework\TestSuite->run() phar:///usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar/phpunit/Framework/TestSuite.php:761
    1.6298   18208936   8. PHPUnit\Framework\TestCase->run() phar:///usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar/phpunit/Framework/TestSuite.php:761
    1.6298   18208936   9. PHPUnit\Framework\TestResult->run() phar:///usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar/phpunit/Framework/TestCase.php:687
    1.6676   18443144  10. PHPUnit\Framework\TestResult->endTest() phar:///usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar/phpunit/Framework/TestResult.php:907
    1.6676   18443144  11. PHPUnit\TextUI\ResultPrinter->endTest() phar:///usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar/phpunit/Framework/TestResult.php:410
    1.6676   18443144  12. PHPUnit\Framework\TestCase->getActualOutput() phar:///usr/local/Cellar/phpunit/7.0.1/libexec/phpunit-7.0.1.phar/phpunit/TextUI/ResultPrinter.php:352

[sebastianbergmann]

A method TestCase::withoutOutput() is not part of PHPUnit, so your reproduce step makes no sense to me.

[sebastianbergmann]

Thank you for your report.

Please provide a minimal, self-contained, reproducing test case that shows the problem you are reporting.

Without such a minimal, self-contained, reproducing test case I will not be able to investigate this issue.

[thedotedge]

Sure thing:

<?php

class CacheProviderTest extends \PHPUnit\Framework\TestCase {

    protected function setUp() {
        $this->setOutputCallback(function() {});
    }

    /** @test */
    public function it_can_clear_all_data() {
        \PHPUnit\Framework\Assert::assertSame('value', 'value');
    }
}

[sebastianbergmann]

The example in #3014 (comment) is not self-contained.

[thedotedge]

Apologies, updated.