The conversion has been done automatically with the following command:
perl -p -i -e 's#this\->assertEquals\((.+?), (.+?)(, '\''(\-|\:|_)|\);)#this->assertEquals($2, $1$3#g' tests/Symfony/Tests/*/*.php tests/Symfony/Tests/*/*/*.php tests/Symfony/Tests/*/*/*.php
... and with some manual tweaking after that