You're a busy developer and you like the idea of automating tests but find most existing solutions much too bloated and cumbersome to deal with.

Rein consists of a single function within a single PHP file. The whole thing can be read and understood in less than 5 minutes. To run tests, simply provide a file or an array of files as an argument to the Rein::run() function:

<?php
require '/path/to/rein.php';
Rein::run('my_tests.php');

Rein will then include and scan the my_tests.php file for functions beginning with test_, executes them as tests and outputs a report. You can run this from the CLI or from the browser. Rein will not dictate the way you organize your test files, how you bootstrap your tests, how you load your fixtures or what goes where and why; it's automated testing for grown-ups. The only thing it assumes is that you'll be using assert() in your tests.

Rein requires PHP 5.3 or greater.

Rein is released under the MIT license.

This section is intended for those who are absolute beginners when it comes to automating tests.

Suppose you're writing a function to convert hexadecimal string representation of a color into an RGB array with 'r', 'g' and 'b' elements. Here's one way you can write it:

<?php
// hex2rgb.php
function hex2rgb($color)
{
    $color = ltrim($color, '#');
    $int = hexdec($color);
    return array(
        'r' => 0xFF & ($int >> 0x10),
        'g' => 0xFF & ($int >> 0x8),
        'b' => 0xFF & $int,
    );
}

And here's the example test file:

<?php
// test_hex2rgb.php
include '/path/to/hex2rgb.php';
include '/path/to/rein.php';

Rein::run(__FILE__); // run the current file

function test_hex2rgb()
{
    assert("hex2rgb('#FFFFFF') == array('r' => 255, 'g' => 255, 'b' => 255);");
    assert("hex2rgb('#FF0000') == array('r' => 255, 'g' => 0, 'b' => 0);");
    assert("hex2rgb('#000000') == array('r' => 0, 'g' => 0, 'b' => 0);");
    assert("hex2rgb('#FFF') == array('r' => 255, 'g' => 255, 'b' => 255);");
    assert("hex2rgb('#FF') == false;");
}

When writing tests, you must take into account as many inputs, outputs, and processing errors you can think of. You must also think of the kinds of edge cases your code will have to endure.

Note that you can put as many test_ functions as you like in one file or divide them up according to their functionality -- whichever makes the most sense to you.

You can then run the test file from the command line or browser. The result is as follows:

Failed 2 of 5 assert(s) in 1 test(s) - completed in 0 seconds.
-------------------------------------------------------------------------------
1. /path/to/your/tests/test_hex2rgb.php:13
	hex2rgb('#FFF') == array('r' => 255, 'g' => 255, 'b' => 255);
-------------------------------------------------------------------------------
2. /path/to/your/tests/test_hex2rgb.php:14
	hex2rgb('#FF') == false;
-------------------------------------------------------------------------------

By using the native assert() function, Rein is able to report every failed assertions in your test files. From the test result above, we know that our hex2rgb() function fails for at least one type of valid input: three-letter abbreviated hexadecimal colors. We can now try to fix our function as follows:

<?php
// hex2rgb.php
// returns an RGB array or false on error
function hex2rgb($color)
{
    $color = ltrim($color, '#');
    if (strlen($color) == 3) {
        $tmp = '';
        for ($i = 0; $i < 3; $i++) $tmp .= str_repeat($color[$i], 2);
        $color = $tmp;
    }
    if (!preg_match('/^([a-f]|[0-9]){3}(([a-f]|[0-9]){3})?$/i', $color)) {
        return false;
    }
    $int = hexdec($color);
    return array(
        'r' => 0xFF & ($int >> 0x10),
        'g' => 0xFF & ($int >> 0x8),
        'b' => 0xFF & $int,
    );
}

And get the following result:

Passed 5 assert(s) in 1 test(s) - completed in 0.001 seconds.

You can expand the example above so that hex2rgb() can gracefully handle other types of errors as well. The idea is by using tests you can prevent certain bugs from occuring provided you stay disciplined and meticulous in adding, updating and running your tests against your code. As you add features, refactor old code and fix existing bugs, your tests will make sure you don't accidentally create new bugs.

The next step would be to automate your tests entirely. Once you've decided the best setup for your tests, you should create a pre-commit hook for your version control system so it'll run your tests just before each commit, and will refuse to do so if any of your tests fails. Another thing you can do if you use make is to automatically run your tests just before packaging and shipping your code.

I hope this section clears up any confusion you may have on automating tests.