Add a test

The attached patch adds a working boilerplate basic functional test.

martin@martin-XPS-13-9370 /var/www/html/d9.localhost $ sudo -u www-data ./vendor/bin/phpunit -c ./web/core ./web/modules/contrib/autofloat/ --debug --printer="\Drupal\Tests\Listeners\HtmlOutputPrinter"
PHPUnit 8.5.3 by Sebastian Bergmann and contributors.

Testing ./web/modules/contrib/autofloat/
Test 'Drupal\Tests\autofloat\Functional\AutofloatTest::testLoad' started
Test 'Drupal\Tests\autofloat\Functional\AutofloatTest::testLoad' ended


Time: 11.1 seconds, Memory: 8.00 MB

OK (1 test, 8 assertions)

HTML output was generated
http://d9.localhost/sites/simpletest/browser_output/Drupal_Tests_autofloat_Functional_AutofloatTest-1-28108239.html
http://d9.localhost/sites/simpletest/browser_output/Drupal_Tests_autofloat_Functional_AutofloatTest-2-28108239.html
http://d9.localhost/sites/simpletest/browser_output/Drupal_Tests_autofloat_Functional_AutofloatTest-3-28108239.html
http://d9.localhost/sites/simpletest/browser_output/Drupal_Tests_autofloat_Functional_AutofloatTest-4-28108239.html
http://d9.localhost/sites/simpletest/browser_output/Drupal_Tests_autofloat_Functional_AutofloatTest-5-28108239.html

Enabled automated testing on the project: https://www.drupal.org/node/1675006/qa

Extend with testing:

• settings form submission
• a generated node on correct floating the images and skipping those excluded.