Core tests

WordPress testing (core) is useful when making a contribution to WordPress core. First thing you must do is to install PHPUnit (version 6, because version 7 doesn't work with WordPress yet).

In your terminal run

curl -L -o phpunit.phar
chmod +x phpunit.phar
mv phpunit.phar /usr/local/bin/phpunit

Or you can run

brew install phpunit
chmod +x phpunit.phar
mv phpunit.phar /usr/local/bin/phpunit

Then check out the test repository. The WordPress tests live in the core development repository, available via SVN at:

svn co wordpress-develop
cd wordpress-develop

Or Git:

git clone git:// wordpress-develop
cd wordpress-develop

Create an empty MySQL database. Be careful not to use existing project database, as test suite will delete all data from the designated database.

Set up a config file. Copy wp-tests-config-sample.php to wp-tests-config.php, and enter the credentials of the newly created database.

Running the test suite

To run unit tests, you need to specify phpunit.xml.dist file. An example might look like

<?xml version="1.0"?>
      <directory prefix="test-" suffix=".php">./tests/</directory>
    <log type="coverage-clover" target="tests/_reports/logs/clover.xml"/>
    <log type="coverage-html" target="tests/_reports/coverage" charset="UTF-8" yui="true" highlight="true" lowUpperBound="35" highLowerBound="70" />
    <log type="testdox-text" target="tests/_reports/testdox/executed.txt"/>
    <log type="testdox-html" target="tests/_reports/testdox/testdox.html" />

Here we've specified that code coverage should be created. For that to be made, Xdebug has to be installed on your system. Be mindfull that Xdebug may significantly reduce the speed of your tests.

In the root directory – next to wp-tests-config.php, the tests/ folder, and the phpunit.xml.dist file, run:


Unit test symbol meaning

Testing inside VVV

VVV comes with a test ready environment wordpress-develop/ where you can test various patches. It already has the test suite set up so you don't need to do any manual steps.

Once in the wordpress-develop/public_html/ folder run

npm install

Then run

npm install -g grunt-cli

After grunt-cli has been installed run

grunt build

If the build fails on node-sass package, try rebuilding it again

npm rebuild node-sass

Notice: The build process is currently under revision (

Applying a patch

Make sure VVV is running and the above steps were completed. Then you can ssh to the vagrant and go to wordpress-develop/public_html/ folder and run

grunt watch &
svn up

Now you’re ready to patch. Find a ticket with patches. This examples uses #11863.

grunt patch:11863

This will show the available patches that you can select (if there were multiple patches). After you select it, you can log in to (or http://src.wordpress-develop.test/). You can test the effects that patch had and after you're done with it you can revert it using

svn revert -R

or with

svn revert -R --cl revertme .

You can comment on the trac ticket with the findings, or create you own patch.

Testing outside of wordpress-develop

You can set up a custom clean installation of WordPress if you don't want to use the oficial one from VVV. In that case, just go to public_html and run

svn co .

This will download all the needed files for testing and patching like the above process.