Setting $_POST for filter_input_array(INPUT_POST) in phpunit test

If the input to filter_input_array can only be set by the initial request, and not changed at run time, then the only way to still test it is to have a your base test proxy to another test script by making an HTTP request with the right POST data and processing the response.

main_test.php:

<?php
$data = array(
    'testname' => 'yourtestname',
    'some_post_var' => 'some_value'
);

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://localhost/proxy_test.php");
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($data));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$response = curl_exec($ch);

curl_close($ch);

if ($response == 'pass') {
  // test passed
}

proxy_test.php

<?php
$test_name $_POST['testname']; // what test to run?
$response = run_test($test_name); // run test that uses filter_input_array
if ($response) {
    echo "pass"; // used by main_test.php to check if test passed
} else {
   echo "fail";
}

It seems like this is a limitation of PHP, filter_input_array() does not allow a $_POST array modified at runtime. See this bug for some more information. The workaround is probably to use one of the other filter functions and pass in the $_POST array yourself.