Why Can’t PHPUnit UnitTest My WordPress Website

I have been researching this issue for days and although many people ask this question I never found a clear and concise answer.

I am running:

• PHP Unit: Version 3.7.21
• WordPress: Version 3.5.1
• OS: Ubuntu 11.10
• MySQL: Version 5.1.69-0ubuntu0.11.10.1
• PHP: Version 5.3.6-13ubuntu3.10

Long story short, I have the basic wordPress core downloaded into a directory on my computer. I have successfully downloaded and installed pear and phpunit. I tested phpunit by writing basic tests on simple php files which worked fine. My issue is when I run phpunit on a wordpress site (which I have not changed the core WP files of).

I get the error:

“PHP Fatal error: Call to a member function main() on a non-member
object in /< root_directory>/functions.php on line 779”.

This error corresponds to this code-segment:

function wp( $query_vars = '' ) {
    global $wp, $wp_query, $wp_the_query;
    $wp->main( $query_vars ); // Line 779

    if ( !isset($wp_the_query) )
        $wp_the_query = $wp_query;
}

After some intense internet crawling I found many people had errors on this exact line so I know there is some general thing like an environment setting or our setup process that gave us all this error.

Some solutions I have read and tried that did not work for me:

• Change the required file in your “index.php” file.
• Place a require of “load.php” above the head in your “index.php” file.
• Re-install WordPress
• Change boot-strap and phpunit environments.

I have been a web-developer for 5 years but I have never used WordPress for one of my clients before. Once I can get this set up writing the unit tests will be easy; but I have no idea what is causing this issue. Any links to guides/tutorials or clear explanations would be greatly appreciated. Thank you for your time.