PHP, will comparing MD5s of print_r output work for testing results?

I'm using code igniter and trying to write tests for the data returned by my 开发者_开发技巧models; CI's testing library is very limited in what it will check for, so I've been doing this:

$test     = "My Test Name";
$expected = md5(print_r(array(array('val','other'), array('new','old','blue')), 1));
$result   = md5(print_r($this->model->method($data), 1));

if($expected == $result) {
    echo "$test [pass]";
}
else {
    echo "$test [fail]";
}

Are there any pitfalls to testing this way? Is there a preferred, simple library that works with CI that I didn't find? The built-in testing library won't allow you to check results with this fine a grain so I find it not terribly helpful.

Yes, that should work just fine, as if both are identical the hashes should be identical as well.

However, why not just examine the output of print_r directly? Or, for that matter, use a completely separate tool like PhpUnit for testing?

Assuming the two variables you are comparing are both arrays, have a look at the inbuilt array_diff() function (http://php.net/manual/en/function.array-diff.php). If you need to compare the indexes of the arrays also, use array_diff_assoc() instead.

However, if you want a complete check for testing multi-dimentional arrays (as yours is), here's a function that should do that for you:

function compare_arrays($first_array, $second_array, $compare_keys = false){
    /* Test if arrays are actually arrays */
    if(!is_array($first_array)){
        // Elements are not arrays
        if(is_array($second_array)){
            // Second array is not array
            return false;
        }

        if($first_array == $second_array){
            return true;
        }
    } elseif(!is_array($second_array)){
        // Second array is not array (first is)
        return false;
    }

    /* Test same number of elements */
    if(count($first_array) != count($second_array)){
        return false;
    }

    $size = count($first_array);
    if($compare_keys){
        // Load keys to compare
        $first_keys = array_keys($first_array);
        $second_keys = array_keys($second_array);
    }

    for($i = 0; $i < $size; $i++){
        if($compare_keys && $first_keys[$i] != $second_keys[$i]){
            // Keys do not match
            return false;
        }

        if(is_array($first_array[$i])){
            // Element is array
            if(!is_array($second_array[$i])){
                // Matching element in other array is not array
                return false;
            }

            $result = compare_arrays($first_array[$i], $second_array[$i], $compare_keys);
            if(!$result){
                // Sub-arrays do not match
                return false;
            }

            // Match - skip iteration
            continue;
        } elseif(is_array($second_array[$i])){
            // Second array element is array (first is not)
            return false;
        }

        // Elements are not arrays
        if($first_array[$i] != $second_array[$i]){
            return false;
        }
    }

    // Match
    return true;
}

Usage:

$br = '<br />';
$array_one = array(4, 5, array(2, 5), 'hello', 'element');

if(compare_arrays($array_one, $array_one)){
    echo 'Match 1'.$br;
} else {
    echo 'No Match 1'.$br;
}

$array_two = array(5, 5, array(2, 5), 'hello', 'element'); // Slightly different

if(compare_arrays($array_one, $array_two)){
    echo 'Match 2'.$br;
} else {
    echo 'No Match 2'.$br;
}

/* Output:
    Match 1
    No Match 2
*/

if($array1 === $array2) { 
       # the arrays are matched with identical keys and values 
       # no matter how deeply nested
}

No hashing required.