PHP Unit Tests: Is it possible to test for a Fatal Error?
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15-10-2019 - |
Question
FWIW I'm using SimpleTest 1.1alpha.
I have a singleton class, and I want to write a unit test that guarantees that the class is a singleton by attempting to instantiate the class (it has a private constructor).
This obviously causes a Fatal Error:
Fatal error: Call to private FrontController::__construct()
Is there any way to "catch" that Fatal Error and report a passed test?
Solution
No. Fatal error stops the execution of the script.
And it's not really necessary to test a singleton in that way. If you insist on checking if constructor is private, you can use ReflectionClass:getConstructor()
public function testCannotInstantiateExternally()
{
$reflection = new \ReflectionClass('\My\Namespace\MyClassName');
$constructor = $reflection->getConstructor();
$this->assertFalse($constructor->isPublic());
}
Another thing to consider is that Singleton classes/objects are an obstacle in TTD since they're difficult to mock.
OTHER TIPS
Here's a complete code snippet of Mchl's answer so people don't have to go through the docs...
public function testCannotInstantiateExternally()
{
$reflection = new \ReflectionClass('\My\Namespace\MyClassName');
$constructor = $reflection->getConstructor();
$this->assertFalse($constructor->isPublic());
}
You can use a concept like PHPUnit's process-isolation.
This means the test code will be executed in a sub process of php. This example shows how this could work.
<?php
// get the test code as string
$testcode = '<?php new '; // will cause a syntax error
// put it in a temporary file
$testfile = tmpfile();
file_put_contents($testfile, $testcode);
exec("php $tempfile", $output, $return_value);
// now you can process the scripts return value and output
// in case of an syntax error the return value is 255
switch($return_value) {
case 0 :
echo 'PASSED';
break;
default :
echo 'FAILED ' . $output;
}
// clean up
unlink($testfile);