Change system test variables to the state system

+++ b/core/modules/system/lib/Drupal/system/Tests/Bootstrap/VariableTest.phpundefined
@@ -35,8 +35,8 @@ public static function getInfo() {
-    variable_set('simpletest_bootstrap_variable_test', $variable);
-    $this->assertIdentical($variable, variable_get('simpletest_bootstrap_variable_test'), 'Setting and retrieving values');
+    state()->set('system_test.bootstrap_variable_test', $variable);
+    $this->assertIdentical($variable, state()->get('system_test.bootstrap_variable_test'), 'Setting and retrieving values');

@@ -44,8 +44,8 @@ function testVariable() {
-    variable_del('simpletest_bootstrap_variable_test');
-    $variable = variable_get('simpletest_bootstrap_variable_test', $default_value);
+    state()->delete('system_test.bootstrap_variable_test');
+    $variable = state()->get('system_test.bootstrap_variable_test', $default_value);
     $this->assertIdentical($variable, $default_value, 'Deleting variables');

@@ -54,10 +54,10 @@ function testVariable() {
-    $this->assertIdentical(NULL, variable_get('simpletest_bootstrap_variable_test'), 'Variables are correctly defaulting to NULL.');
+    $this->assertIdentical(NULL, state()->get('system_test.bootstrap_variable_test'), 'Variables are correctly defaulting to NULL.');
 
     // Tests passing 5 to the default parameter.
-    $this->assertIdentical(5, variable_get('simpletest_bootstrap_variable_test', 5), 'The default variable parameter is passed through correctly.');
+    $this->assertIdentical(5, state()->get('system_test.bootstrap_variable_test') ?: 5, 'The default variable parameter is passed through correctly.');

We shouldn't actually convert the variable tests. These are specifically to test the variable system and make no sense if converted to the state system. If the variable system does get removed we'll just delete all these tests. I'll remove these from the meta-issue.

+++ b/core/modules/system/lib/Drupal/system/Tests/Module/DependencyTest.phpundefined
@@ -157,7 +157,7 @@ function testModuleEnableOrder() {
-    $this->assertIdentical(variable_get('test_module_enable_order', array()), $expected_order);
+    $this->assertIdentical(state()->get('system_test.module_enable_order'), $expected_order);

All implementations of state()->get() in this patch need to specify a default by doing something along the lines of state()->get('system_test.module_enable_order') ?: array()

+++ b/core/modules/system/tests/modules/system_test/system_test.moduleundefined
@@ -58,8 +58,8 @@ function system_test_menu() {
-    'page callback' => 'variable_get',
-    'page arguments' => array('simpletest_bootstrap_variable_test', NULL),
+    'page callback' => 'state()->get',
+    'page arguments' => array('system_test.bootstrap_variable_test'),

Don't worry about this because state()->get() already returns NULL when the key doesn't exist.

Looks great passes tests

Committed and pushed to 8.x. Thanks!