Unserialize error when @runInSeparateProcess

Question

I am implementing a module that will provide an API to work with and manage PHP sessions. I am testing the Session\Manager implementation that will allow users to start sessions, set IDs, get IDs, destroy sessions, etc. I am testing the methods in this class in a separate process, by using PHPUnit's @runInSeparateProcess annotation. When I use this annotation I get an exception thrown by PHPUnit due to an unserialization error. When I do not use the annotation the test runs as expected and fails on null not being equal to false.

Here's the test causing the error. So far no implementation details have been made, all methods for the interface exist but perform no operations.

class ManagerTest extends PHPUnitTestCase {

    /**
     * Ensures that if the session has not been started yet the sessionExists
     * method returns false.
     *
     * @runInSeparateProcess
     */
    public function testSessionExistsWhenSessionHasNotBeenStarted() {
        $Manager = new \Session\Manager();
        $this->assertFalse($Manager->sessionExists());
    }

}

I was able to trace the problem down to the following PHPUnit_Util_PHP::runJob() method. I am running PHPUnit 3.7.5 and the runJob method being invoked is:

/**
 * Runs a single job (PHP code) using a separate PHP process.
 *
 * @param  string                       $job
 * @param  PHPUnit_Framework_TestCase   $test
 * @param  PHPUnit_Framework_TestResult $result
 * @return array|null
 * @throws PHPUnit_Framework_Exception
 */
public function runJob($job, PHPUnit_Framework_Test $test = NULL, PHPUnit_Framework_TestResult $result = NULL)
{
    $process = proc_open(
      $this->getPhpBinary(),
      array(
        0 => array('pipe', 'r'),
        1 => array('pipe', 'w'),
        2 => array('pipe', 'w')
      ),
      $pipes
    );

    if (!is_resource($process)) {
        throw new PHPUnit_Framework_Exception(
          'Unable to create process for process isolation.'
        );
    }

    if ($result !== NULL) {
        $result->startTest($test);
    }

    $this->process($pipes[0], $job);
    fclose($pipes[0]);

    $stdout = stream_get_contents($pipes[1]);
    fclose($pipes[1]);

    $stderr = stream_get_contents($pipes[2]);
    fclose($pipes[2]);

    proc_close($process);
    $this->cleanup();

    if ($result !== NULL) {
        $this->processChildResult($test, $result, $stdout, $stderr);
    } else {
        return array('stdout' => $stdout, 'stderr' => $stderr);
    }
}

The line $stdout = stream_get_contents($pipes[1]); results in $stdout being equal to a long string of ?. In $this->processChildResult the value in $stdout is unserialized and the invalid value passed to this function triggers a warning, resulting in an exception being thrown. I've also been able to determine that the return value of $this->getPhpBinary() is /usr/bin/php.

Exception message thrown:

PHPUnit_Framework_Exception: ???...???"*???...??


Caused by
ErrorException: unserialize(): Error at offset 0 of 10081 bytes

Thanks to hek2mgl the PHP code in $job can be reviewed at this gist holding the output of a var_dump on $job. I created a link as it is a fair amount of code and this question is already quite long.

I've reached the end of my knowledge for this particular domain and not sure how go about debugging this problem further. I'm not sure why the @runInSeparateProcess is failing and why the $stdout from running a separate process results in a long string of ? marks. What might be causing this issue and how could I go about resolving it? I'm at a standstill for this module as future tests will require running in a separate process to ensure sessions being started and destroyed don't impact tests.

• PHP: 5.3.15
• PHPUnit: 3.7.5
• Error caused in IDE and command line test runners

Answer 1

Ok, I figured out what is going on here and boy is it a doozy.

During testing the framework attempts to preserve global state. In the PHPUnit_Framework_TestCase::run() function the current globals are converted into a string of PHP code by PHPUnit_Util_GlobalState::getGlobalsAsString(). I am currently using an autoloading library to take care of requiring appropriate class files. This class was declared in a variable that was in the global scope, causing a serialization of that object to be put into the $GLOBALS array created by getGlobalsAsString(). This serialization, for whatever reason, includes the null byte character \u0000. When you attempt to unserialize this you get an error and is ultimately causing the output to be corrupted as well.

I fixed this issue by create a function in my test bootstrap that creates the autoloading object outside of the global scope. Now that the script is no longer attempting to unserialize a null byte the script produces no errors and the test case works as expected. This is a really funky issue, not sure if its an error in my code, PHPUnit's code or an internal error with the serialize function.

---

Alternatively you can override the run() function in your test case and explicitly set the test case to not preserve global state. This is probably a cleaner solution as you could easily run into other issues with requiring all included files again as is the default behavior.

class ManagerTest extends PHPUnit_Framework_TestCase {

    public function run(PHPUnit_Framework_TestResult $result = null) {
        $this->setPreserveGlobalState(false);
        parent::run($result);
    }

}

Global state must be set before the PHPUnit_Framework_TestCase::run() function is invoked. This is likely the only way to reliably set the global state preservation properly.

Answer 2

The $job argument to PHPUnit_Util_PHP::runJob() is php code generated by PHPUnit that wraps the code of your test method in a way that it can be executed as a commandline script (clever trick!). The isolated test will output serialized php data about test results back to phpunit.

You can investigate this code if you would add the following line on top pf PHPUnit_Util_PHP::runJob()

file_put_contents('isolated.php', $job);

After executing the failed test again the file isolated.php should have been created in the current directory. You can have a look at code can execute it (in the current folder) by typing

php isolated.php

Do you see any output that looks messy?

Also you should debug the method PHPUnit_Util_PHP::processChildResult(). The method is responsible for deserializing and checking test results. Place some echos or var_dumps there or use a debugger. When having a look at this method it is very likely that the problem is caused by illegal output from the test method.

Answer 3

Please try set in php.ini:

detect_unicode = Off

Worked for me.