diff --git a/core/modules/simpletest/simpletest.module b/core/modules/simpletest/simpletest.module
index 1b603ab..780491c 100644
--- a/core/modules/simpletest/simpletest.module
+++ b/core/modules/simpletest/simpletest.module
@@ -138,7 +138,7 @@ function simpletest_run_tests($test_list) {
     unset($test_list['phpunit']);
   }
 
-  $test_id = \Drupal::database()->insert('simpletest_test_id')
+  $test_id = Database::getConnection()->insert('simpletest_test_id')
     ->useDefaults(['test_id'])
     ->execute();
 
diff --git a/core/tests/Drupal/KernelTests/Core/Database/BasicSyntaxTest.php b/core/tests/Drupal/KernelTests/Core/Database/BasicSyntaxTest.php
index 841dfca..ec12d05 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/BasicSyntaxTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/BasicSyntaxTest.php
@@ -76,7 +76,7 @@ public function testConcatWsFields() {
    * Tests escaping of LIKE wildcards.
    */
   public function testLikeEscape() {
-    \Drupal::database()->insert('test')
+    $this->connection->insert('test')
       ->fields([
         'name' => 'Ring_',
       ])
@@ -102,7 +102,7 @@ public function testLikeEscape() {
    * Tests a LIKE query containing a backslash.
    */
   public function testLikeBackslash() {
-    \Drupal::database()->insert('test')
+    $this->connection->insert('test')
       ->fields(['name'])
       ->values([
         'name' => 'abcde\f',
diff --git a/core/tests/Drupal/KernelTests/Core/Database/CaseSensitivityTest.php b/core/tests/Drupal/KernelTests/Core/Database/CaseSensitivityTest.php
index 6205793..1a2e900 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/CaseSensitivityTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/CaseSensitivityTest.php
@@ -15,7 +15,7 @@ class CaseSensitivityTest extends DatabaseTestBase {
   public function testCaseSensitiveInsert() {
     $num_records_before = db_query('SELECT COUNT(*) FROM {test}')->fetchField();
 
-    \Drupal::database()->insert('test')
+    $this->connection->insert('test')
       ->fields([
         // A record already exists with name 'John'.
         'name' => 'john',
diff --git a/core/tests/Drupal/KernelTests/Core/Database/InsertDefaultsTest.php b/core/tests/Drupal/KernelTests/Core/Database/InsertDefaultsTest.php
index e526675..13ef94e 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/InsertDefaultsTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/InsertDefaultsTest.php
@@ -15,7 +15,7 @@ class InsertDefaultsTest extends DatabaseTestBase {
    * Tests that we can run a query that uses default values for everything.
    */
   public function testDefaultInsert() {
-    $query = \Drupal::database()->insert('test')->useDefaults(['job']);
+    $query = $this->connection->insert('test')->useDefaults(['job']);
     $id = $query->execute();
 
     $schema = drupal_get_module_schema('database_test', 'test');
@@ -31,7 +31,7 @@ public function testDefaultEmptyInsert() {
     $num_records_before = (int) db_query('SELECT COUNT(*) FROM {test}')->fetchField();
 
     try {
-      \Drupal::database()->insert('test')->execute();
+      $this->connection->insert('test')->execute();
       // This is only executed if no exception has been thrown.
       $this->fail('Expected exception NoFieldsException has not been thrown.');
     }
@@ -47,7 +47,7 @@ public function testDefaultEmptyInsert() {
    * Tests that we can insert fields with values and defaults in the same query.
    */
   public function testDefaultInsertWithFields() {
-    $query = \Drupal::database()->insert('test')
+    $query = $this->connection->insert('test')
       ->fields(['name' => 'Bob'])
       ->useDefaults(['job']);
     $id = $query->execute();
diff --git a/core/tests/Drupal/KernelTests/Core/Database/InsertLobTest.php b/core/tests/Drupal/KernelTests/Core/Database/InsertLobTest.php
index 6ca6f3b..1098438 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/InsertLobTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/InsertLobTest.php
@@ -15,7 +15,7 @@ class InsertLobTest extends DatabaseTestBase {
   public function testInsertOneBlob() {
     $data = "This is\000a test.";
     $this->assertTrue(strlen($data) === 15, 'Test data contains a NULL.');
-    $id = \Drupal::database()->insert('test_one_blob')
+    $id = $this->connection->insert('test_one_blob')
       ->fields(['blob1' => $data])
       ->execute();
     $r = db_query('SELECT * FROM {test_one_blob} WHERE id = :id', [':id' => $id])->fetchAssoc();
@@ -26,7 +26,7 @@ public function testInsertOneBlob() {
    * Tests that we can insert multiple blob fields in the same query.
    */
   public function testInsertMultipleBlob() {
-    $id = \Drupal::database()->insert('test_two_blobs')
+    $id = $this->connection->insert('test_two_blobs')
       ->fields([
         'blob1' => 'This is',
         'blob2' => 'a test',
diff --git a/core/tests/Drupal/KernelTests/Core/Database/InsertTest.php b/core/tests/Drupal/KernelTests/Core/Database/InsertTest.php
index 5b3b218..cbc5c9d 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/InsertTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/InsertTest.php
@@ -15,7 +15,7 @@ class InsertTest extends DatabaseTestBase {
   public function testSimpleInsert() {
     $num_records_before = db_query('SELECT COUNT(*) FROM {test}')->fetchField();
 
-    $query = \Drupal::database()->insert('test');
+    $query = $this->connection->insert('test');
     $query->fields([
       'name' => 'Yoko',
       'age' => '29',
@@ -37,7 +37,7 @@ public function testSimpleInsert() {
   public function testMultiInsert() {
     $num_records_before = (int) db_query('SELECT COUNT(*) FROM {test}')->fetchField();
 
-    $query = \Drupal::database()->insert('test');
+    $query = $this->connection->insert('test');
     $query->fields([
       'name' => 'Larry',
       'age' => '30',
@@ -76,7 +76,7 @@ public function testMultiInsert() {
   public function testRepeatedInsert() {
     $num_records_before = db_query('SELECT COUNT(*) FROM {test}')->fetchField();
 
-    $query = \Drupal::database()->insert('test');
+    $query = $this->connection->insert('test');
 
     $query->fields([
       'name' => 'Larry',
@@ -119,7 +119,7 @@ public function testRepeatedInsert() {
   public function testInsertFieldOnlyDefinition() {
     // This is useful for importers, when we want to create a query and define
     // its fields once, then loop over a multi-insert execution.
-    \Drupal::database()->insert('test')
+    $this->connection->insert('test')
       ->fields(['name', 'age'])
       ->values(['Larry', '30'])
       ->values(['Curly', '31'])
@@ -137,7 +137,7 @@ public function testInsertFieldOnlyDefinition() {
    * Tests that inserts return the proper auto-increment ID.
    */
   public function testInsertLastInsertID() {
-    $id = \Drupal::database()->insert('test')
+    $id = $this->connection->insert('test')
       ->fields([
         'name' => 'Larry',
         'age' => '30',
@@ -165,7 +165,7 @@ public function testInsertSelectFields() {
     // SELECT tp.age AS age, tp.name AS name, tp.job AS job
     // FROM test_people tp
     // WHERE tp.name = 'Meredith'
-    \Drupal::database()->insert('test')
+    $this->connection->insert('test')
       ->from($query)
       ->execute();
 
@@ -186,7 +186,7 @@ public function testInsertSelectAll() {
     // SELECT *
     // FROM test_people tp
     // WHERE tp.name = 'Meredith'
-    \Drupal::database()->insert('test_people_copy')
+    $this->connection->insert('test_people_copy')
       ->from($query)
       ->execute();
 
diff --git a/core/tests/Drupal/KernelTests/Core/Database/InvalidDataTest.php b/core/tests/Drupal/KernelTests/Core/Database/InvalidDataTest.php
index 12d5661..f088514 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/InvalidDataTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/InvalidDataTest.php
@@ -18,7 +18,7 @@ class InvalidDataTest extends DatabaseTestBase {
   public function testInsertDuplicateData() {
     // Try to insert multiple records where at least one has bad data.
     try {
-      \Drupal::database()->insert('test')
+      $this->connection->insert('test')
         ->fields(['name', 'age', 'job'])
         ->values([
           'name' => 'Elvis',
@@ -75,7 +75,7 @@ public function testInsertDuplicateDataFromSelect() {
     // Insert multiple records in 'test_people' where one has bad data
     // (duplicate key). A 'Meredith' record has already been inserted
     // in ::setUp.
-    \Drupal::database()->insert('test_people')
+    $this->connection->insert('test_people')
       ->fields(['name', 'age', 'job'])
       ->values([
         'name' => 'Elvis',
@@ -109,7 +109,7 @@ public function testInsertDuplicateDataFromSelect() {
         ->orderBy('name');
 
       // Try inserting from the subselect.
-      \Drupal::database()->insert('test')
+      $this->connection->insert('test')
         ->from($query)
         ->execute();
 
diff --git a/core/tests/Drupal/KernelTests/Core/Database/QueryTest.php b/core/tests/Drupal/KernelTests/Core/Database/QueryTest.php
index 6aee10e..bfe60b6 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/QueryTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/QueryTest.php
@@ -100,7 +100,7 @@ public function testConditionOperatorArgumentsSQLInjection() {
     // Attempt SQLi via union query with no unsafe characters.
     $this->enableModules(['user']);
     $this->installEntitySchema('user');
-    \Drupal::database()->insert('test')
+    $this->connection->insert('test')
       ->fields(['name' => '123456'])
       ->execute();
     $injection = "= 1 UNION ALL SELECT password FROM user WHERE uid =";
@@ -117,7 +117,7 @@ public function testConditionOperatorArgumentsSQLInjection() {
     }
 
     // Attempt SQLi via union query - uppercase tablename.
-    \Drupal::database()->insert('TEST_UPPERCASE')
+    $this->connection->insert('TEST_UPPERCASE')
       ->fields(['name' => 'secrets'])
       ->execute();
     $injection = "IS NOT NULL) UNION ALL SELECT name FROM {TEST_UPPERCASE} -- ";
diff --git a/core/tests/Drupal/KernelTests/Core/Database/RegressionTest.php b/core/tests/Drupal/KernelTests/Core/Database/RegressionTest.php
index 5ec1ad1..e4cc868 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/RegressionTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/RegressionTest.php
@@ -24,7 +24,7 @@ class RegressionTest extends DatabaseTestBase {
   public function testRegression_310447() {
     // That's a 255 character UTF-8 string.
     $job = str_repeat("é", 255);
-    \Drupal::database()->insert('test')
+    db_insert('test')
       ->fields([
         'name' => $this->randomMachineName(),
         'age' => 20,
diff --git a/core/tests/Drupal/KernelTests/Core/Database/SelectSubqueryTest.php b/core/tests/Drupal/KernelTests/Core/Database/SelectSubqueryTest.php
index 298b0e1..c035d35 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/SelectSubqueryTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/SelectSubqueryTest.php
@@ -209,7 +209,7 @@ public function testJoinSubquerySelect() {
    */
   public function testExistsSubquerySelect() {
     // Put George into {test_people}.
-    \Drupal::database()->insert('test_people')
+    $this->connection->insert('test_people')
       ->fields([
         'name' => 'George',
         'age' => 27,
@@ -239,7 +239,7 @@ public function testExistsSubquerySelect() {
    */
   public function testNotExistsSubquerySelect() {
     // Put George into {test_people}.
-    \Drupal::database()->insert('test_people')
+    $this->connection->insert('test_people')
       ->fields([
         'name' => 'George',
         'age' => 27,
diff --git a/core/tests/Drupal/KernelTests/Core/Database/SelectTest.php b/core/tests/Drupal/KernelTests/Core/Database/SelectTest.php
index e632757..a0ac960 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/SelectTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/SelectTest.php
@@ -402,7 +402,7 @@ public function testRandomOrder() {
     // after shuffling it (in other words, nearly impossible).
     $number_of_items = 52;
     while (db_query("SELECT MAX(id) FROM {test}")->fetchField() < $number_of_items) {
-      \Drupal::database()->insert('test')->fields(['name' => $this->randomMachineName()])->execute();
+      $this->connection->insert('test')->fields(['name' => $this->randomMachineName()])->execute();
     }
 
     // First select the items in order and make sure we get an ordered list.
diff --git a/core/tests/Drupal/KernelTests/Core/Database/TransactionTest.php b/core/tests/Drupal/KernelTests/Core/Database/TransactionTest.php
index 098e542..7ef25bf 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/TransactionTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/TransactionTest.php
@@ -57,7 +57,7 @@ protected function transactionOuterLayer($suffix, $rollback = FALSE, $ddl_statem
     $txn = db_transaction();
 
     // Insert a single row into the testing table.
-    \Drupal::database()->insert('test')
+    $this->connection->insert('test')
       ->fields([
         'name' => 'David' . $suffix,
         'age' => '24',
@@ -107,7 +107,7 @@ protected function transactionInnerLayer($suffix, $rollback = FALSE, $ddl_statem
     $this->assertTrue($depth < $depth2, 'Transaction depth is has increased with new transaction.');
 
     // Insert a single row into the testing table.
-    \Drupal::database()->insert('test')
+    $this->connection->insert('test')
       ->fields([
         'name' => 'Daniel' . $suffix,
         'age' => '19',
@@ -310,7 +310,7 @@ public function testTransactionWithDdlStatement() {
    * Inserts a single row into the testing table.
    */
   protected function insertRow($name) {
-    \Drupal::database()->insert('test')
+    $this->connection->insert('test')
       ->fields([
         'name' => $name,
       ])
diff --git a/core/tests/Drupal/KernelTests/Core/Database/UpdateLobTest.php b/core/tests/Drupal/KernelTests/Core/Database/UpdateLobTest.php
index 4cf76ea..c9f142e 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/UpdateLobTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/UpdateLobTest.php
@@ -15,7 +15,7 @@ class UpdateLobTest extends DatabaseTestBase {
   public function testUpdateOneBlob() {
     $data = "This is\000a test.";
     $this->assertTrue(strlen($data) === 15, 'Test data contains a NULL.');
-    $id = \Drupal::database()->insert('test_one_blob')
+    $id = $this->connection->insert('test_one_blob')
       ->fields(['blob1' => $data])
       ->execute();
 
@@ -33,7 +33,7 @@ public function testUpdateOneBlob() {
    * Confirms that we can update two blob columns in the same table.
    */
   public function testUpdateMultipleBlob() {
-    $id = \Drupal::database()->insert('test_two_blobs')
+    $id = $this->connection->insert('test_two_blobs')
       ->fields([
         'blob1' => 'This is',
         'blob2' => 'a test',
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/FieldSqlStorageTest.php b/core/tests/Drupal/KernelTests/Core/Entity/FieldSqlStorageTest.php
index 2f51516..d8fc633 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/FieldSqlStorageTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/FieldSqlStorageTest.php
@@ -123,7 +123,7 @@ public function testFieldLoad() {
 
     // Generate values and insert them directly in the storage tables.
     $values = [];
-    $query = \Drupal::database()->insert($this->revisionTable)->fields($columns);
+    $query = Database::getConnection()->insert($this->revisionTable)->fields($columns);
     foreach ($revision_ids as $revision_id) {
       // Put one value too many.
       for ($delta = 0; $delta <= $this->fieldCardinality; $delta++) {
@@ -133,7 +133,7 @@ public function testFieldLoad() {
       }
       $query->execute();
     }
-    $query = \Drupal::database()->insert($this->table)->fields($columns);
+    $query = Database::getConnection()->insert($this->table)->fields($columns);
     foreach ($values[$revision_id] as $delta => $value) {
       $query->values([$bundle, 0, $entity->id(), $revision_id, $delta, $entity->language()->getId(), $value]);
     }
@@ -167,8 +167,8 @@ public function testFieldLoad() {
     // loaded.
     $unavailable_langcode = 'xx';
     $values = [$bundle, 0, $entity->id(), $entity->getRevisionId(), 0, $unavailable_langcode, mt_rand(1, 127)];
-    \Drupal::database()->insert($this->table)->fields($columns)->values($values)->execute();
-    \Drupal::database()->insert($this->revisionTable)->fields($columns)->values($values)->execute();
+    Database::getConnection()->insert($this->table)->fields($columns)->values($values)->execute();
+    Database::getConnection()->insert($this->revisionTable)->fields($columns)->values($values)->execute();
     $entity = $storage->load($entity->id());
     $this->assertFalse(array_key_exists($unavailable_langcode, $entity->{$this->fieldName}));
   }