Improve Jest configuration (#4370)
Improve Jest configuration (#4370)

* Remove Less workaround

* Move expect helper

* Remove nesting for accept tests

* Remove nesting for reject tests

* Improve test case names, which contain line-breaks

* Improve comments

* Abstract boilerplate setup

stylelint/stylelint,stylelint/stylelint,stylelint/stylelint,stylelint/stylelint