Issue #2454649 by Aki Tendo, dawehner: Cache Optimization and hardening -- [PP-1] Use assert() instead of exceptions in Cache::merge(Tags|Contexts)

Issue #2410497 by alvar0hurtad0, sdstyles, hussainweb, webchick, jhodgdon, mpdonadio: Update remaining url() and _l() calls in comments/documentation

Issue #2576533 by alexpott, stefan.r, Wim Leers, dawehner, xjm, effulgentsia, catch: Rename SafeStringInterface to MarkupInterface and move related classes

Issue #2571291 by pwolanin, aneek, stefan.r: In WebTest code, assertEqual and assertIdentical should always show the 2 values on failure

Issue #2566447 by stefan.r, joelpittet, alexpott, lauriii, dawehner: Cast safe string objects to string or use assertEqual() in some assertIdentical() comparisons

Issue #2560729 by stefan.r, lauriii: Cast objects implementing SafeStringInterface to string in TestBase / WebTestBase

Issue #2564353 by alexpott, joelpittet, xjm, justAChris, nlisgo, subhojit777: Remove !placeholder usage from SafeMarkup::format()

Issue #2501319 by joelpittet, cwells, stefan.r, YesCT, nlisgo, Cottser, cmanalansan, dawehner, xjm, alexpott, josephdpurcell: Remove SafeMarkup::set() in Error::renderExceptionSafe() and _drupal_log_error() and improve backtrace formatting consistency in _drupal_log_error(), Error::renderExceptionSafe(), and DefaultExceptionSubscriber::onHtml()

Issue #1713332 by amateescu, Xen, droplet, bzrudi71, znerol, czigor, pp, wulff, Damien Tournoud: The SQLite database driver fails to drop simpletest tables

Issue #2304461 by dawehner, neclimdul, naveenvalecha, jibran, tim.plunkett, phenaproxima, Xano, hussainweb, sun, hitesh-jain, amateescu, alexpott, daffie, Mile23, Wim Leers, larowlan: KernelTestBaseTNG™

Issue #2487498 by Cristian.Andrei, Scott Weston, iMiksu: Make randomString always return a > to avoid random test fails

Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #2384675 by sidharrell, cilefen, Mile23, damiankloip, dawehner, Wim Leers, alexpott, neclimdul: Deprecate conf_path()

Issue #2383871 by mgifford, rpayanm, a_thakur, maximpodorov, AohRveTPV, jhodgdon: Spellchecking Drupal - PHP

Issue #2491155 by mikeburrelljr, Mac_Weber, opdavies: Update drupal.org and kernel.org URLs in core modules (Follow-up to 2489912)

Issue #2478167 by andypost, znerol: Generate proper value for sessionName property in BrowserTestBase

Issue #2417549 by alexpott, znerol, benjy, Berdir: Drupal\migrate_drupal\Tests\d6\MigrateFileTest fail in MigrateTestBase

Issue #1897058 by disasm, rteijeiro: Replace "boolean" with "bool" when used as param/return/var type

Issue #2457887 by prateekMehta, stefan.r, rpayanm, alexpott: Use Utility\SafeMarkup class instead of Utility\String for placeholder(), checkPlain(),format() functions

Issue #2451085 by dawehner, Arla: _drupal_log_error() passes NULL to ThemeManager::setActiveTheme(), violating its typehint

Issue #2315791 by alexpott, cilefen, dawehner: Add functionality to open results in browser window to run-tests.sh

Issue #2144669 by Mile23, daffie, Nitesh Sethia: Improve/Refactor TestBase Through Expanded Unit Testing

Issue #2363341 by tim.plunkett, donquixote, adci_contributor: Throw exception in Drupal::service() and friends, if container not initialized yet

Revert "Issue #2144669 by Mile23, Nitesh Sethia: Improve/Refactor TestBase Through Expanded Unit Testing"

This reverts commit 921317dc.

Issue #2417515 by idebr: TestBase::prepareDatabasePrefix() refers to DrupalWebTestCase that has been renamed

Issue #2050759 by tim.plunkett, fietserwin: Move drupal_chmod and other code in file.inc to a Drupal\Core\File\FileSystem class

Issue #2381763 by chx, webflo: Adjust the order of container yamls to override settings per environment

Issue #2406543 by alexpott: Remove ConfigFactory::setOverrideState and ConfigFactory::getOverrideState()

Issue #2392319 by alexpott, effulgentsia: Config objects (but not config entities) should by default be immutable

Issue #2382195 by tibbsa, subhojit777, tadityar, cilefen, Mile23: Clean-up simpletest module test members - ensure property definition and use of camelCase naming convention

Issue #2395395 by alexpott, effulgentsia, Gábor Hojtsy: TestBase lacks a config method to be used consistently in tests

Issue #2170235 by Berdir, penyaskito, larowlan, alexpott, sushyl: file_private_path should be in $settings, like file_public_path

Issue #2183983 by Gábor Hojtsy, vijaycs85, Berdir, Wim Leers, webflo, alexpott: Find hidden configuration schema issues

Issue #2324055 by dawehner, cilefen, znerol: Split up the module manager into runtime information and extension information

Issue #2028109 by tim.plunkett, almaudoh, twistor, larowlan, slashrsm, Berdir, Arla, neclimdul, Cottser: Convert hook_stream_wrappers() to tagged services.

Issue #2343661 by larowlan, tim.plunkett | xjm: Rename l() to _l() and url() to _url(), and document replacements.

Issue #1860594 by penyaskito, damiankloip, xjm, alexpott, sun: Ensure that randomString() always returns a character that needs to be escaped for HTML.