How to Test Submissions from Forms that Use the POST Method

An important part of developing online forms is testing. One area of testing I've always wanted to better with is making sure input types like radio buttons can't accept values which are not allowed. In this week's post, we go over my primary method of testing. That way we can discuss a faster way next time.

Simple Form

Let's say you have a page named "myform.php" that contains the following form:

<form method="post" action="myform.php">
     <p>Were there any transmission problems?</p>
     <div><label><input type="radio" name="transmissionProblems" value="Yes"> Yes</label></div>
     <div><label><input type="radio" name="transmissionProblems" value="No"> No</label></div>
     <div><label><input type="radio" name="transmissionProblems" value="N/A"> N/A</label></div>
     <div><input type="submit" name="submit" value="Submit"></div>
</form>

Then on the same page you have a simple validation script. The script makes sure the transmissionProblems radio button can only be set to "Yes", "No", or "N/A".

<?php
//IF THE FORM WAS SUBMITTED
if($_SERVER['REQUEST_METHOD'] == 'POST') {
     //DECLARE VALID RESPONSES
     $validResponses = array('Yes', 'No', 'N/A');
 
     //IF INVALID RESPONSE
     if(!in_array($_POST['transmissionProblems'], $validResponses)) {
          print 'Unknown response to "Were there any transmission problems?"';
 
     //ELSE...VALID RESPONSE
     } else {
          print 'Thanks for responding';
     }
}
?>
<form method="post" action="myform.php">
     <p>Were there any transmission problems?</p>
     <div><label><input type="radio" name="transmissionProblems" value="Yes"> Yes</label></div>
     <div><label><input type="radio" name="transmissionProblems" value="No"> No</label></div>
     <div><label><input type="radio" name="transmissionProblems" value="N/A"> N/A</label></div>
     <div><input type="submit" name="submit" value="Submit"></div>
</form>

Now it's easy to make sure the valid responses work, but how do you test the invalid responses. Since the form uses the POST method, the data will be passed behind the scenes. There doesn't seem to be a quick way to inject bad values like you can with the GET method.

Solution

One method for testing is to hard code the values to test. For example, you could overwrite the POST variable by adding the following line:

<?php
//IF THE FORM WAS SUBMITTED
if($_SERVER['REQUEST_METHOD'] == 'POST') {
     //DECLARE VALID RESPONSES
     $validResponses = array('Yes', 'No', 'N/A');
 
 
     $_POST['transmissionProblems'] = 'BAD VALUE';
 
 
     //IF INVALID RESPONSE
     if(!in_array($_POST['transmissionProblems'], $validResponses)) {
          //...
?>

Of course, it's a bit cumbersome to change the hard-coded value every time you want to test a different value. To speed things along, you could utilize the advice posted in "Setting up a Makeshift Test Environment for Experimenting with PHP Code".

Related Posts

• How to Test Form Submissions: Using Google Chrome to Change Form Values