Issue #2226207 by lauriii, mgbellaire, Cottser, m1r1k, Mark Carver, LinL, rachel_norfolk, rteijeiro, skwashd, davidhernandez, euphoric_mv: Make 'template' the default output option for hook_theme().
Issue #2350301 by mitrpaka: Replace extend of deprecated DrupalUnitTestBase with KernelTestBase in Contextual.