Ask HN: How is quality tests on complex softwares like IDEs?

How companies like Intellij IDEA does to manage quality assurance on systems with complex requirements like IDEs and development tools?

IDEs usually supports a large amount of configurations, each release must be tested to assure the features are working. These features must be tested with different combinations, because features can eventually affect each other. It's easy to calculate that this is a huge work to do each time a new version is released. Even with tests being automated, they need to be developed.

My guess is that they have large test suites, being executed on each new release by multiple really specialised teams on parallel, using multiple software engineering techniques. Am I right?