Issue #1937212 by ACF: Change node test variables 'node_test_change_view_mode()' and 'node_access_test_secret_catalan()' to the state system.

Issue #1797200 by pillarsdotnet, boombatower, solotandem, ZenDoodles, sun, xjm, yched, Damien Tournoud: (crediting those who worked on previous versions of this patch as well) Remove t() from test assertions in node module

Issue #1739994 by pp, das-peter, Gábor Hojtsy: Use the Language class universally instead of stdObj instances.

Issue #1711070 by kid_icarus, tim.plunkett, xjm, droplet, zendoodles and cam8001: Convert tests to use ::$modules property instead of parent::setUp($modules).