class TransactionTest

class TransactionTest extends DatabaseTestBase {
  
  /**
   * Keeps track of the post-transaction callback action executed.
   */
  protected ?string $postTransactionCallbackAction = NULL;
  
  /**
   * {@inheritdoc}
   */
  protected function setUp() : void {
    parent::setUp();
    // Set the transaction manager to trigger warnings when appropriate.
    $this->connection
      ->transactionManager()->triggerWarningWhenUnpilingOnVoidTransaction = TRUE;
  }
  
  /**
   * Create a root Drupal transaction.
   */
  protected function createRootTransaction(string $name = '', bool $insertRow = TRUE) : Transaction {
    $this->assertFalse($this->connection
      ->inTransaction());
    $this->assertSame(0, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Start root transaction. Corresponds to 'BEGIN TRANSACTION' on the
    // database.
    $transaction = $this->connection
      ->startTransaction($name);
    $this->assertTrue($this->connection
      ->inTransaction());
    $this->assertSame(1, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Insert a single row into the testing table.
    if ($insertRow) {
      $this->insertRow('David');
      $this->assertRowPresent('David');
    }
    return $transaction;
  }
  
  /**
   * Create a Drupal savepoint transaction after root.
   */
  protected function createFirstSavepointTransaction(string $name = '', bool $insertRow = TRUE) : Transaction {
    $this->assertTrue($this->connection
      ->inTransaction());
    $this->assertSame(1, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Starts a savepoint transaction. Corresponds to 'SAVEPOINT savepoint_1'
    // on the database. The name can be changed by the $name argument.
    $savepoint = $this->connection
      ->startTransaction($name);
    $this->assertTrue($this->connection
      ->inTransaction());
    $this->assertSame(2, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Insert a single row into the testing table.
    if ($insertRow) {
      $this->insertRow('Roger');
      $this->assertRowPresent('Roger');
    }
    return $savepoint;
  }
  
  /**
   * Encapsulates a transaction's "inner layer" with an "outer layer".
   *
   * This "outer layer" transaction starts and then encapsulates the "inner
   * layer" transaction. This nesting is used to evaluate whether the database
   * transaction API properly supports nesting. By "properly supports," we mean
   * the outer transaction continues to exist regardless of what functions are
   * called and whether those functions start their own transactions.
   *
   * In contrast, a typical database would commit the outer transaction, start
   * a new transaction for the inner layer, commit the inner layer transaction,
   * and then be confused when the outer layer transaction tries to commit its
   * transaction (which was already committed when the inner transaction
   * started).
   *
   * @param string $suffix
   *   Suffix to add to field values to differentiate tests.
   */
  protected function transactionOuterLayer(string $suffix) : void {
    $txn = $this->connection
      ->startTransaction();
    // Insert a single row into the testing table.
    $this->connection
      ->insert('test')
      ->fields([
      'name' => 'David' . $suffix,
      'age' => '24',
    ])
      ->execute();
    $this->assertTrue($this->connection
      ->inTransaction(), 'In transaction before calling nested transaction.');
    // We're already in a transaction, but we call ->transactionInnerLayer
    // to nest another transaction inside the current one.
    $this->transactionInnerLayer($suffix);
    $this->assertTrue($this->connection
      ->inTransaction(), 'In transaction after calling nested transaction.');
    $txn->commitOrRelease();
  }
  
  /**
   * Creates an "inner layer" transaction.
   *
   * This "inner layer" transaction is either used alone or nested inside of the
   * "outer layer" transaction.
   *
   * @param string $suffix
   *   Suffix to add to field values to differentiate tests.
   */
  protected function transactionInnerLayer(string $suffix) : void {
    $depth = $this->connection
      ->transactionManager()
      ->stackDepth();
    // Start a transaction. If we're being called from ->transactionOuterLayer,
    // then we're already in a transaction. Normally, that would make starting
    // a transaction here dangerous, but the database API handles this problem
    // for us by tracking the nesting and avoiding the danger.
    $txn = $this->connection
      ->startTransaction();
    $depth2 = $this->connection
      ->transactionManager()
      ->stackDepth();
    $this->assertSame($depth + 1, $depth2, 'Transaction depth has increased with new transaction.');
    // Insert a single row into the testing table.
    $this->connection
      ->insert('test')
      ->fields([
      'name' => 'Daniel' . $suffix,
      'age' => '19',
    ])
      ->execute();
    $this->assertTrue($this->connection
      ->inTransaction(), 'In transaction inside nested transaction.');
    $txn->commitOrRelease();
  }
  
  /**
   * Tests root transaction rollback.
   */
  public function testRollbackRoot() : void {
    $transaction = $this->createRootTransaction();
    // Rollback. Since we are at the root, the transaction is closed.
    // Corresponds to 'ROLLBACK' on the database.
    $transaction->rollBack();
    $this->assertRowAbsent('David');
    $this->assertFalse($this->connection
      ->inTransaction());
    $this->assertSame(0, $this->connection
      ->transactionManager()
      ->stackDepth());
  }
  
  /**
   * Tests root transaction rollback after savepoint rollback.
   */
  public function testRollbackRootAfterSavepointRollback() : void {
    $transaction = $this->createRootTransaction();
    $savepoint = $this->createFirstSavepointTransaction();
    // Rollback savepoint. It should get released too. Corresponds to 'ROLLBACK
    // TO savepoint_1' plus 'RELEASE savepoint_1' on the database.
    $savepoint->rollBack();
    $this->assertRowPresent('David');
    $this->assertRowAbsent('Roger');
    $this->assertTrue($this->connection
      ->inTransaction());
    $this->assertSame(1, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Try to rollback root. No savepoint is active, this should succeed.
    $transaction->rollBack();
    $this->assertRowAbsent('David');
    $this->assertRowAbsent('Roger');
    $this->assertFalse($this->connection
      ->inTransaction());
    $this->assertSame(0, $this->connection
      ->transactionManager()
      ->stackDepth());
  }
  
  /**
   * Tests root transaction rollback failure when savepoint is open.
   */
  public function testRollbackRootWithActiveSavepoint() : void {
    $transaction = $this->createRootTransaction();
    // phpcs:ignore DrupalPractice.CodeAnalysis.VariableAnalysis
    $savepoint = $this->createFirstSavepointTransaction();
    // Try to rollback root. Since a savepoint is active, this should fail.
    $this->expectException(TransactionOutOfOrderException::class);
    $this->expectExceptionMessageMatches("/^Error attempting rollback of .*\\\\drupal_transaction\\. Active stack: .*\\\\drupal_transaction > .*\\\\savepoint_1/");
    $transaction->rollBack();
  }
  
  /**
   * Tests savepoint transaction rollback.
   */
  public function testRollbackSavepoint() : void {
    $transaction = $this->createRootTransaction();
    $savepoint = $this->createFirstSavepointTransaction();
    // Rollback savepoint. It should get released too. Corresponds to 'ROLLBACK
    // TO savepoint_1' plus 'RELEASE savepoint_1' on the database.
    $savepoint->rollBack();
    $this->assertRowPresent('David');
    $this->assertRowAbsent('Roger');
    $this->assertTrue($this->connection
      ->inTransaction());
    $this->assertSame(1, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Insert a row.
    $this->insertRow('Syd');
    // Commit root.
    $transaction->commitOrRelease();
    $this->assertRowPresent('David');
    $this->assertRowAbsent('Roger');
    $this->assertRowPresent('Syd');
    $this->assertFalse($this->connection
      ->inTransaction());
    $this->assertSame(0, $this->connection
      ->transactionManager()
      ->stackDepth());
  }
  
  /**
   * Tests savepoint transaction commit after rollback.
   */
  public function testCommitAfterRollbackSameSavepoint() : void {
    $transaction = $this->createRootTransaction();
    $savepoint = $this->createFirstSavepointTransaction();
    // Rollback savepoint. It should get released too. Corresponds to 'ROLLBACK
    // TO savepoint_1' plus 'RELEASE savepoint_1' on the database.
    $savepoint->rollBack();
    $this->assertRowPresent('David');
    $this->assertRowAbsent('Roger');
    $this->assertTrue($this->connection
      ->inTransaction());
    $this->assertSame(1, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Insert a row.
    $this->insertRow('Syd');
    // Try releasing savepoint. Should fail since it was released already.
    try {
      $savepoint->commitOrRelease();
      $this->fail('Expected TransactionOutOfOrderException was not thrown');
    } catch (\Exception $e) {
      $this->assertInstanceOf(TransactionOutOfOrderException::class, $e);
      $this->assertMatchesRegularExpression("/^Error attempting commit of .*\\\\savepoint_1\\. Active stack: .*\\\\drupal_transaction/", $e->getMessage());
    }
    $this->assertRowPresent('David');
    $this->assertRowAbsent('Roger');
    $this->assertRowPresent('Syd');
    $this->assertTrue($this->connection
      ->inTransaction());
    $this->assertSame(1, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Commit root.
    $transaction->commitOrRelease();
    $this->assertRowPresent('David');
    $this->assertRowAbsent('Roger');
    $this->assertRowPresent('Syd');
    $this->assertFalse($this->connection
      ->inTransaction());
    $this->assertSame(0, $this->connection
      ->transactionManager()
      ->stackDepth());
  }
  
  /**
   * Tests savepoint transaction rollback after commit.
   */
  public function testRollbackAfterCommitSameSavepoint() : void {
    $transaction = $this->createRootTransaction();
    $savepoint = $this->createFirstSavepointTransaction();
    // Release savepoint. Corresponds to 'RELEASE savepoint_1' on the database.
    $savepoint->commitOrRelease();
    $this->assertRowPresent('David');
    $this->assertRowPresent('Roger');
    $this->assertTrue($this->connection
      ->inTransaction());
    $this->assertSame(1, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Insert a row.
    $this->insertRow('Syd');
    // Try rolling back savepoint. Should fail since it was released already.
    try {
      $savepoint->rollback();
      $this->fail('Expected TransactionOutOfOrderException was not thrown');
    } catch (\Exception $e) {
      $this->assertInstanceOf(TransactionOutOfOrderException::class, $e);
      $this->assertMatchesRegularExpression("/^Error attempting rollback of .*\\\\savepoint_1\\. Active stack: .*\\\\drupal_transaction/", $e->getMessage());
    }
    $this->assertRowPresent('David');
    $this->assertRowPresent('Roger');
    $this->assertRowPresent('Syd');
    $this->assertTrue($this->connection
      ->inTransaction());
    $this->assertSame(1, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Commit root.
    $transaction->commitOrRelease();
    $this->assertRowPresent('David');
    $this->assertRowPresent('Roger');
    $this->assertRowPresent('Syd');
    $this->assertFalse($this->connection
      ->inTransaction());
    $this->assertSame(0, $this->connection
      ->transactionManager()
      ->stackDepth());
  }
  
  /**
   * Tests savepoint transaction duplicated rollback.
   */
  public function testRollbackTwiceSameSavepoint() : void {
    // phpcs:ignore DrupalPractice.CodeAnalysis.VariableAnalysis
    $transaction = $this->createRootTransaction();
    $savepoint = $this->createFirstSavepointTransaction();
    // Rollback savepoint. It should get released too. Corresponds to 'ROLLBACK
    // TO savepoint_1' plus 'RELEASE savepoint_1' on the database.
    $savepoint->rollBack();
    $this->assertRowPresent('David');
    $this->assertRowAbsent('Roger');
    $this->assertTrue($this->connection
      ->inTransaction());
    $this->assertSame(1, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Insert a row.
    $this->insertRow('Syd');
    // Rollback savepoint again. Should fail since it was released already.
    try {
      $savepoint->rollBack();
      $this->fail('Expected TransactionOutOfOrderException was not thrown');
    } catch (\Exception $e) {
      $this->assertInstanceOf(TransactionOutOfOrderException::class, $e);
      $this->assertMatchesRegularExpression("/^Error attempting rollback of .*\\\\savepoint_1\\. Active stack: .*\\\\drupal_transaction/", $e->getMessage());
    }
    $this->assertRowPresent('David');
    $this->assertRowAbsent('Roger');
    $this->assertRowPresent('Syd');
    $this->assertTrue($this->connection
      ->inTransaction());
    $this->assertSame(1, $this->connection
      ->transactionManager()
      ->stackDepth());
  }
  
  /**
   * Tests savepoint transaction rollback failure when later savepoints exist.
   */
  public function testRollbackSavepointWithLaterSavepoint() : void {
    // phpcs:ignore DrupalPractice.CodeAnalysis.VariableAnalysis
    $transaction = $this->createRootTransaction();
    $savepoint1 = $this->createFirstSavepointTransaction();
    // Starts another savepoint transaction. Corresponds to 'SAVEPOINT
    // savepoint_2' on the database.
    // phpcs:ignore DrupalPractice.CodeAnalysis.VariableAnalysis
    $savepoint2 = $this->connection
      ->startTransaction();
    $this->assertTrue($this->connection
      ->inTransaction());
    $this->assertSame(3, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Insert a row.
    $this->insertRow('Syd');
    $this->assertRowPresent('David');
    $this->assertRowPresent('Roger');
    $this->assertRowPresent('Syd');
    // Try to rollback to savepoint 1. Out of order.
    $this->expectException(TransactionOutOfOrderException::class);
    $this->expectExceptionMessageMatches("/^Error attempting rollback of .*\\\\savepoint_1\\. Active stack: .*\\\\drupal_transaction > .*\\\\savepoint_1 > .*\\\\savepoint_2/");
    $savepoint1->rollBack();
  }
  
  /**
   * Tests commit does not fail when committing after DDL.
   *
   * In core, SQLite and PostgreSql databases support transactional DDL, MySql
   * does not.
   */
  public function testCommitAfterDdl() : void {
    $transaction = $this->createRootTransaction();
    $savepoint = $this->createFirstSavepointTransaction();
    $this->executeDDLStatement();
    $this->assertRowPresent('David');
    $this->assertRowPresent('Roger');
    if ($this->connection
      ->supportsTransactionalDDL()) {
      $this->assertTrue($this->connection
        ->inTransaction());
      $this->assertSame(2, $this->connection
        ->transactionManager()
        ->stackDepth());
    }
    else {
      $this->assertFalse($this->connection
        ->inTransaction());
    }
    $this->assertRowPresent('David');
    $this->assertRowPresent('Roger');
    if ($this->connection
      ->supportsTransactionalDDL()) {
      $savepoint->commitOrRelease();
      $this->assertTrue($this->connection
        ->inTransaction());
      $this->assertSame(1, $this->connection
        ->transactionManager()
        ->stackDepth());
    }
    else {
      set_error_handler(static function (int $errno, string $errstr) : bool {
        throw new \ErrorException($errstr);
      });
      try {
        $savepoint->commitOrRelease();
      } catch (\ErrorException $e) {
        $this->assertSame('Transaction::commitOrRelease() was not processed because a prior execution of a DDL statement already committed the transaction.', $e->getMessage());
      } finally {
        restore_error_handler();
      }
      $this->assertFalse($this->connection
        ->inTransaction());
    }
    if ($this->connection
      ->supportsTransactionalDDL()) {
      $transaction->commitOrRelease();
    }
    else {
      set_error_handler(static function (int $errno, string $errstr) : bool {
        throw new \ErrorException($errstr);
      });
      try {
        $transaction->commitOrRelease();
      } catch (\ErrorException $e) {
        $this->assertSame('Transaction::commitOrRelease() was not processed because a prior execution of a DDL statement already committed the transaction.', $e->getMessage());
      } finally {
        restore_error_handler();
      }
    }
    $this->assertRowPresent('David');
    $this->assertRowPresent('Roger');
    $this->assertFalse($this->connection
      ->inTransaction());
  }
  
  /**
   * Tests a committed transaction.
   *
   * The behavior of this test should be identical for connections that support
   * transactions and those that do not.
   */
  public function testCommittedTransaction() : void {
    // Create two nested transactions. The changes should be committed.
    $this->transactionOuterLayer('A');
    // Because we committed, both of the inserted rows should be present.
    $saved_age = $this->connection
      ->query('SELECT [age] FROM {test} WHERE [name] = :name', [
      ':name' => 'DavidA',
    ])
      ->fetchField();
    $this->assertSame('24', $saved_age, 'Can retrieve DavidA row after commit.');
    $saved_age = $this->connection
      ->query('SELECT [age] FROM {test} WHERE [name] = :name', [
      ':name' => 'DanielA',
    ])
      ->fetchField();
    $this->assertSame('19', $saved_age, 'Can retrieve DanielA row after commit.');
  }
  
  /**
   * Tests the compatibility of transactions with DDL statements.
   */
  public function testTransactionWithDdlStatement() : void {
    // First, test that a commit works normally, even with DDL statements.
    $transaction = $this->createRootTransaction('', FALSE);
    $this->insertRow('row');
    $this->executeDDLStatement();
    if ($this->connection
      ->supportsTransactionalDDL()) {
      $transaction->commitOrRelease();
    }
    else {
      set_error_handler(static function (int $errno, string $errstr) : bool {
        throw new \ErrorException($errstr);
      });
      try {
        $transaction->commitOrRelease();
      } catch (\ErrorException $e) {
        $this->assertSame('Transaction::commitOrRelease() was not processed because a prior execution of a DDL statement already committed the transaction.', $e->getMessage());
      } finally {
        restore_error_handler();
      }
    }
    $this->assertRowPresent('row');
    // Even in different order.
    $this->cleanUp();
    $transaction = $this->createRootTransaction('', FALSE);
    $this->executeDDLStatement();
    $this->insertRow('row');
    if ($this->connection
      ->supportsTransactionalDDL()) {
      $transaction->commitOrRelease();
    }
    else {
      set_error_handler(static function (int $errno, string $errstr) : bool {
        throw new \ErrorException($errstr);
      });
      try {
        $transaction->commitOrRelease();
      } catch (\ErrorException $e) {
        $this->assertSame('Transaction::commitOrRelease() was not processed because a prior execution of a DDL statement already committed the transaction.', $e->getMessage());
      } finally {
        restore_error_handler();
      }
    }
    $this->assertRowPresent('row');
    // Even with stacking.
    $this->cleanUp();
    $transaction = $this->createRootTransaction('', FALSE);
    $transaction2 = $this->createFirstSavepointTransaction('', FALSE);
    $this->executeDDLStatement();
    if ($this->connection
      ->supportsTransactionalDDL()) {
      $transaction2->commitOrRelease();
    }
    else {
      set_error_handler(static function (int $errno, string $errstr) : bool {
        throw new \ErrorException($errstr);
      });
      try {
        $transaction2->commitOrRelease();
      } catch (\ErrorException $e) {
        $this->assertSame('Transaction::commitOrRelease() was not processed because a prior execution of a DDL statement already committed the transaction.', $e->getMessage());
      } finally {
        restore_error_handler();
      }
    }
    $transaction3 = $this->connection
      ->startTransaction();
    $this->insertRow('row');
    $transaction3->commitOrRelease();
    if ($this->connection
      ->supportsTransactionalDDL()) {
      $transaction->commitOrRelease();
    }
    else {
      try {
        $transaction->commitOrRelease();
        $this->fail('TransactionOutOfOrderException was expected, but did not throw.');
      } catch (TransactionOutOfOrderException) {
        // Just continue, this is out or order since $transaction3 started a
        // new root.
      }
    }
    $this->assertRowPresent('row');
    // A transaction after a DDL statement should still work the same.
    $this->cleanUp();
    $transaction = $this->createRootTransaction('', FALSE);
    $transaction2 = $this->createFirstSavepointTransaction('', FALSE);
    $this->executeDDLStatement();
    if ($this->connection
      ->supportsTransactionalDDL()) {
      $transaction2->commitOrRelease();
    }
    else {
      set_error_handler(static function (int $errno, string $errstr) : bool {
        throw new \ErrorException($errstr);
      });
      try {
        $transaction2->commitOrRelease();
      } catch (\ErrorException $e) {
        $this->assertSame('Transaction::commitOrRelease() was not processed because a prior execution of a DDL statement already committed the transaction.', $e->getMessage());
      } finally {
        restore_error_handler();
      }
    }
    $transaction3 = $this->connection
      ->startTransaction();
    $this->insertRow('row');
    $transaction3->rollBack();
    if ($this->connection
      ->supportsTransactionalDDL()) {
      $transaction->commitOrRelease();
    }
    else {
      try {
        $transaction->commitOrRelease();
        $this->fail('TransactionOutOfOrderException was expected, but did not throw.');
      } catch (TransactionOutOfOrderException) {
        // Just continue, this is out or order since $transaction3 started a
        // new root.
      }
    }
    $this->assertRowAbsent('row');
    // The behavior of a rollback depends on the type of database server.
    if ($this->connection
      ->supportsTransactionalDDL()) {
      // For database servers that support transactional DDL, a rollback
      // of a transaction including DDL statements should be possible.
      $this->cleanUp();
      $transaction = $this->createRootTransaction('', FALSE);
      $this->insertRow('row');
      $this->executeDDLStatement();
      $transaction->rollBack();
      $this->assertRowAbsent('row');
      // Including with stacking.
      $this->cleanUp();
      $transaction = $this->createRootTransaction('', FALSE);
      $transaction2 = $this->createFirstSavepointTransaction('', FALSE);
      $this->executeDDLStatement();
      $transaction2->commitOrRelease();
      $transaction3 = $this->connection
        ->startTransaction();
      $this->insertRow('row');
      $transaction3->commitOrRelease();
      $this->assertRowPresent('row');
      $transaction->rollBack();
      $this->assertRowAbsent('row');
    }
  }
  
  /**
   * Tests rollback after a DDL statement when no transactional DDL supported.
   */
  public function testRollbackAfterDdlStatementForNonTransactionalDdlDatabase() : void {
    if ($this->connection
      ->supportsTransactionalDDL()) {
      $this->markTestSkipped('This test only works for database that do not support transactional DDL.');
    }
    // For database servers that do not support transactional DDL,
    // the DDL statement should commit the transaction stack.
    $this->cleanUp();
    $transaction = $this->createRootTransaction('', FALSE);
    $reflectionMethod = new \ReflectionMethod(get_class($this->connection
      ->transactionManager()), 'getConnectionTransactionState');
    $this->assertSame(1, $this->connection
      ->transactionManager()
      ->stackDepth());
    $this->assertEquals(ClientConnectionTransactionState::Active, $reflectionMethod->invoke($this->connection
      ->transactionManager()));
    $this->insertRow('row');
    $this->executeDDLStatement();
    $this->assertSame(0, $this->connection
      ->transactionManager()
      ->stackDepth());
    $this->assertEquals(ClientConnectionTransactionState::Voided, $reflectionMethod->invoke($this->connection
      ->transactionManager()));
    // Try to rollback the root transaction. Since the DDL already committed
    // it, it should fail.
    set_error_handler(static function (int $errno, string $errstr) : bool {
      throw new \ErrorException($errstr);
    });
    try {
      $transaction->rollBack();
    } catch (\ErrorException $e) {
      $this->assertSame('Transaction::rollBack() failed because of a prior execution of a DDL statement.', $e->getMessage());
    } finally {
      restore_error_handler();
    }
    try {
      $transaction->commitOrRelease();
      $this->fail('TransactionOutOfOrderException was expected, but did not throw.');
    } catch (TransactionOutOfOrderException) {
      // Just continue, the attempted rollback made the overall state to
      // ClientConnectionTransactionState::RollbackFailed.
    }
    $manager = $this->connection
      ->transactionManager();
    $this->assertSame(0, $manager->stackDepth());
    $reflectedTransactionState = new \ReflectionMethod($manager, 'getConnectionTransactionState');
    $this->assertSame(ClientConnectionTransactionState::RollbackFailed, $reflectedTransactionState->invoke($manager));
    $this->assertRowPresent('row');
  }
  
  /**
   * Inserts a single row into the testing table.
   */
  protected function insertRow(string $name) : void {
    $this->connection
      ->insert('test')
      ->fields([
      'name' => $name,
    ])
      ->execute();
  }
  
  /**
   * Executes a DDL statement.
   */
  protected function executeDDLStatement() : void {
    static $count = 0;
    $table = [
      'fields' => [
        'id' => [
          'type' => 'serial',
          'unsigned' => TRUE,
          'not null' => TRUE,
        ],
      ],
      'primary key' => [
        'id',
      ],
    ];
    $this->connection
      ->schema()
      ->createTable('database_test_' . ++$count, $table);
  }
  
  /**
   * Starts over for a new test.
   */
  protected function cleanUp() : void {
    $this->connection
      ->truncate('test')
      ->execute();
    $this->postTransactionCallbackAction = NULL;
    $this->assertSame(0, $this->connection
      ->transactionManager()
      ->stackDepth());
  }
  
  /**
   * Asserts that a given row is present in the test table.
   *
   * @param string $name
   *   The name of the row.
   * @param string $message
   *   The message to log for the assertion.
   *
   * @internal
   */
  public function assertRowPresent(string $name, ?string $message = NULL) : void {
    $present = (bool) $this->connection
      ->query('SELECT 1 FROM {test} WHERE [name] = :name', [
      ':name' => $name,
    ])
      ->fetchField();
    $this->assertTrue($present, $message ?? "Row '{$name}' should be present, but it actually does not exist.");
  }
  
  /**
   * Asserts that a given row is absent from the test table.
   *
   * @param string $name
   *   The name of the row.
   * @param string $message
   *   The message to log for the assertion.
   *
   * @internal
   */
  public function assertRowAbsent(string $name, ?string $message = NULL) : void {
    $present = (bool) $this->connection
      ->query('SELECT 1 FROM {test} WHERE [name] = :name', [
      ':name' => $name,
    ])
      ->fetchField();
    $this->assertFalse($present, $message ?? "Row '{$name}' should be absent, but it actually exists.");
  }
  
  /**
   * Tests transaction stacking, commit, and rollback.
   */
  public function testTransactionStacking() : void {
    // Standard case: pop the inner transaction before the outer transaction.
    $transaction = $this->createRootTransaction('', FALSE);
    $this->insertRow('outer');
    $transaction2 = $this->createFirstSavepointTransaction('', FALSE);
    $this->insertRow('inner');
    // Pop the inner transaction.
    $transaction2->commitOrRelease();
    $this->assertTrue($this->connection
      ->inTransaction(), 'Still in a transaction after popping the inner transaction');
    // Pop the outer transaction.
    $transaction->commitOrRelease();
    $this->assertFalse($this->connection
      ->inTransaction(), 'Transaction closed after popping the outer transaction');
    $this->assertRowPresent('outer');
    $this->assertRowPresent('inner');
    // Rollback the inner transaction.
    $this->cleanUp();
    $transaction = $this->createRootTransaction('', FALSE);
    $this->insertRow('outer');
    $transaction2 = $this->createFirstSavepointTransaction('', FALSE);
    $this->insertRow('inner');
    // Now rollback the inner transaction.
    $transaction2->rollBack();
    $this->assertTrue($this->connection
      ->inTransaction(), 'Still in a transaction after popping the outer transaction');
    // Pop the outer transaction, it should commit.
    $this->insertRow('outer-after-inner-rollback');
    $transaction->commitOrRelease();
    $this->assertFalse($this->connection
      ->inTransaction(), 'Transaction closed after popping the inner transaction');
    $this->assertRowPresent('outer');
    $this->assertRowAbsent('inner');
    $this->assertRowPresent('outer-after-inner-rollback');
  }
  
  /**
   * Tests that transactions can continue to be used if a query fails.
   */
  public function testQueryFailureInTransaction() : void {
    $transaction = $this->createRootTransaction('test_transaction', FALSE);
    $this->connection
      ->schema()
      ->dropTable('test');
    // Test a failed query using the query() method.
    try {
      $this->connection
        ->query('SELECT [age] FROM {test} WHERE [name] = :name', [
        ':name' => 'David',
      ])
        ->fetchField();
      $this->fail('Using the query method should have failed.');
    } catch (\Exception) {
      // Just continue testing.
    }
    // Test a failed select query.
    try {
      $this->connection
        ->select('test')
        ->fields('test', [
        'name',
      ])
        ->execute();
      $this->fail('Select query should have failed.');
    } catch (\Exception) {
      // Just continue testing.
    }
    // Test a failed insert query.
    try {
      $this->connection
        ->insert('test')
        ->fields([
        'name' => 'David',
        'age' => '24',
      ])
        ->execute();
      $this->fail('Insert query should have failed.');
    } catch (\Exception) {
      // Just continue testing.
    }
    // Test a failed update query.
    try {
      $this->connection
        ->update('test')
        ->fields([
        'name' => 'Tiffany',
      ])
        ->condition('id', 1)
        ->execute();
      $this->fail('Update query should have failed.');
    } catch (\Exception) {
      // Just continue testing.
    }
    // Test a failed delete query.
    try {
      $this->connection
        ->delete('test')
        ->condition('id', 1)
        ->execute();
      $this->fail('Delete query should have failed.');
    } catch (\Exception) {
      // Just continue testing.
    }
    // Test a failed merge query.
    try {
      $this->connection
        ->merge('test')
        ->key('job', 'Presenter')
        ->fields([
        'age' => '31',
        'name' => 'Tiffany',
      ])
        ->execute();
      $this->fail('Merge query should have failed.');
    } catch (\Exception) {
      // Just continue testing.
    }
    // Test a failed upsert query.
    try {
      $this->connection
        ->upsert('test')
        ->key('job')
        ->fields([
        'job',
        'age',
        'name',
      ])
        ->values([
        'job' => 'Presenter',
        'age' => 31,
        'name' => 'Tiffany',
      ])
        ->execute();
      $this->fail('Upsert query should have failed.');
    } catch (\Exception) {
      // Just continue testing.
    }
    // Create the missing schema and insert a row.
    $this->installSchema('database_test', [
      'test',
    ]);
    $this->connection
      ->insert('test')
      ->fields([
      'name' => 'David',
      'age' => '24',
    ])
      ->execute();
    // Commit the transaction.
    if ($this->connection
      ->supportsTransactionalDDL()) {
      $transaction->commitOrRelease();
    }
    else {
      set_error_handler(static function (int $errno, string $errstr) : bool {
        throw new \ErrorException($errstr);
      });
      try {
        $transaction->commitOrRelease();
      } catch (\ErrorException $e) {
        $this->assertSame('Transaction::commitOrRelease() was not processed because a prior execution of a DDL statement already committed the transaction.', $e->getMessage());
      } finally {
        restore_error_handler();
      }
    }
    $saved_age = $this->connection
      ->query('SELECT [age] FROM {test} WHERE [name] = :name', [
      ':name' => 'David',
    ])
      ->fetchField();
    $this->assertEquals('24', $saved_age);
  }
  
  /**
   * Tests releasing a savepoint before last is safe.
   */
  public function testReleaseIntermediateSavepoint() : void {
    $transaction = $this->createRootTransaction();
    $savepoint1 = $this->createFirstSavepointTransaction('', FALSE);
    // Starts a savepoint transaction. Corresponds to 'SAVEPOINT savepoint_2'
    // on the database.
    $savepoint2 = $this->connection
      ->startTransaction();
    $this->assertSame(3, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Starts a savepoint transaction. Corresponds to 'SAVEPOINT savepoint_3'
    // on the database.
    // phpcs:ignore DrupalPractice.CodeAnalysis.VariableAnalysis
    $savepoint3 = $this->connection
      ->startTransaction();
    $this->assertSame(4, $this->connection
      ->transactionManager()
      ->stackDepth());
    // Starts a savepoint transaction. Corresponds to 'SAVEPOINT savepoint_4'
    // on the database.
    // phpcs:ignore DrupalPractice.CodeAnalysis.VariableAnalysis
    $savepoint4 = $this->connection
      ->startTransaction();
    $this->assertSame(5, $this->connection
      ->transactionManager()
      ->stackDepth());
    $this->insertRow('row');
    // Release savepoint transaction. Corresponds to 'RELEASE SAVEPOINT
    // savepoint_2' on the database.
    $savepoint2->commitOrRelease();
    // Since we have committed an intermediate savepoint Transaction object,
    // the savepoints created later have been dropped by the database already.
    $this->assertSame(2, $this->connection
      ->transactionManager()
      ->stackDepth());
    $this->assertRowPresent('row');
    // Commit the remaining Transaction objects. The client transaction is
    // eventually committed.
    $savepoint1->commitOrRelease();
    $transaction->commitOrRelease();
    $this->assertFalse($this->connection
      ->inTransaction());
    $this->assertRowPresent('row');
  }
  
  /**
   * Tests committing a transaction while savepoints are active.
   */
  public function testCommitWithActiveSavepoint() : void {
    $transaction = $this->createRootTransaction();
    // phpcs:ignore DrupalPractice.CodeAnalysis.VariableAnalysis
    $savepoint1 = $this->createFirstSavepointTransaction('', FALSE);
    // Starts a savepoint transaction. Corresponds to 'SAVEPOINT savepoint_2'
    // on the database.
    $savepoint2 = $this->connection
      ->startTransaction();
    $this->assertSame(3, $this->connection
      ->transactionManager()
      ->stackDepth());
    $this->insertRow('row');
    // Commit the root transaction.
    $transaction->commitOrRelease();
    // Since we have committed the outer (root) Transaction object, the inner
    // (savepoint) ones have been dropped by the database already, and we are
    // no longer in an active transaction state.
    $this->assertSame(0, $this->connection
      ->transactionManager()
      ->stackDepth());
    $this->assertFalse($this->connection
      ->inTransaction());
    $this->assertRowPresent('row');
    // Trying to release the inner (savepoint) Transaction object, throws an
    // exception since it was dropped by the database already, and removed from
    // our transaction stack.
    $this->expectException(TransactionOutOfOrderException::class);
    $this->expectExceptionMessageMatches("/^Error attempting commit of .*\\\\savepoint_2\\. Active stack: .* empty/");
    $savepoint2->commitOrRelease();
  }
  
  /**
   * Tests for transaction names.
   */
  public function testTransactionName() : void {
    $transaction = $this->createRootTransaction('', FALSE);
    $this->assertSame('drupal_transaction', $transaction->name());
    $savepoint1 = $this->createFirstSavepointTransaction('', FALSE);
    $this->assertSame('savepoint_1', $savepoint1->name());
    $this->expectException(TransactionNameNonUniqueException::class);
    $this->expectExceptionMessage("savepoint_1 is already in use.");
    $this->connection
      ->startTransaction('savepoint_1');
  }
  
  /**
   * Tests for arbitrary transaction names.
   */
  public function testArbitraryTransactionNames() : void {
    $transaction = $this->createRootTransaction('TinkyWinky', FALSE);
    // Despite setting a name, the root transaction is always named
    // 'drupal_transaction'.
    $this->assertSame('drupal_transaction', $transaction->name());
    $savepoint1 = $this->createFirstSavepointTransaction('Dipsy', FALSE);
    $this->assertSame('Dipsy', $savepoint1->name());
    $this->expectException(TransactionNameNonUniqueException::class);
    $this->expectExceptionMessage("Dipsy is already in use.");
    $this->connection
      ->startTransaction('Dipsy');
  }
  
  /**
   * Tests that adding a post-transaction callback fails with no transaction.
   */
  public function testRootTransactionEndCallbackAddedWithoutTransaction() : void {
    $this->expectException(\LogicException::class);
    $this->connection
      ->transactionManager()
      ->addPostTransactionCallback([
      $this,
      'rootTransactionCallback',
    ]);
  }
  
  /**
   * Tests post-transaction callback executes after transaction commit.
   */
  public function testRootTransactionEndCallbackCalledOnCommit() : void {
    $transaction = $this->createRootTransaction('', FALSE);
    $this->connection
      ->transactionManager()
      ->addPostTransactionCallback([
      $this,
      'rootTransactionCallback',
    ]);
    $this->insertRow('row');
    $this->assertNull($this->postTransactionCallbackAction);
    $this->assertRowAbsent('rtcCommit');
    // Callbacks are processed only when destructing the transaction.
    // Executing a commit is not sufficient by itself.
    $transaction->commitOrRelease();
    $this->assertNull($this->postTransactionCallbackAction);
    $this->assertRowPresent('row');
    $this->assertRowAbsent('rtcCommit');
    // Destruct the transaction.
    unset($transaction);
    // The post-transaction callback should now have inserted a 'rtcCommit'
    // row.
    $this->assertSame('rtcCommit', $this->postTransactionCallbackAction);
    $this->assertRowPresent('row');
    $this->assertRowPresent('rtcCommit');
  }
  
  /**
   * Tests post-transaction callback executes after transaction rollback.
   */
  public function testRootTransactionEndCallbackCalledAfterRollbackAndDestruction() : void {
    $transaction = $this->createRootTransaction('', FALSE);
    $this->connection
      ->transactionManager()
      ->addPostTransactionCallback([
      $this,
      'rootTransactionCallback',
    ]);
    $this->insertRow('row');
    $this->assertNull($this->postTransactionCallbackAction);
    // Callbacks are processed only when destructing the transaction.
    // Executing a rollback is not sufficient by itself.
    $transaction->rollBack();
    $this->assertNull($this->postTransactionCallbackAction);
    $this->assertRowAbsent('rtcCommit');
    $this->assertRowAbsent('rtcRollback');
    $this->assertRowAbsent('row');
    // Destruct the transaction.
    unset($transaction);
    // The post-transaction callback should now have inserted a 'rtcRollback'
    // row.
    $this->assertSame('rtcRollback', $this->postTransactionCallbackAction);
    $this->assertRowAbsent('rtcCommit');
    $this->assertRowPresent('rtcRollback');
    $this->assertRowAbsent('row');
  }
  
  /**
   * Tests post-transaction callback executes after a DDL statement.
   */
  public function testRootTransactionEndCallbackCalledAfterDdlAndDestruction() : void {
    $transaction = $this->createRootTransaction('', FALSE);
    $this->connection
      ->transactionManager()
      ->addPostTransactionCallback([
      $this,
      'rootTransactionCallback',
    ]);
    $this->insertRow('row');
    $this->assertNull($this->postTransactionCallbackAction);
    // Callbacks are processed only when destructing the transaction.
    // Executing a DDL statement is not sufficient itself.
    // We cannot use truncate here, since it has protective code to fall back
    // to a transactional delete when in transaction. We drop an unrelated
    // table instead.
    $this->connection
      ->schema()
      ->dropTable('test_people');
    $this->assertNull($this->postTransactionCallbackAction);
    $this->assertRowAbsent('rtcCommit');
    $this->assertRowAbsent('rtcRollback');
    $this->assertRowPresent('row');
    // Destruct the transaction.
    unset($transaction);
    // The post-transaction callback should now have inserted a 'rtcCommit'
    // row.
    $this->assertSame('rtcCommit', $this->postTransactionCallbackAction);
    $this->assertRowPresent('rtcCommit');
    $this->assertRowAbsent('rtcRollback');
    $this->assertRowPresent('row');
  }
  
  /**
   * Tests post-transaction rollback executes after a DDL statement.
   *
   * For database servers that support transactional DDL, a rollback of a
   * transaction including DDL statements is possible.
   */
  public function testRootTransactionEndCallbackCalledAfterDdlAndRollbackForTransactionalDdlDatabase() : void {
    if (!$this->connection
      ->supportsTransactionalDDL()) {
      $this->markTestSkipped('This test only works for database supporting transactional DDL.');
    }
    $transaction = $this->createRootTransaction('', FALSE);
    $this->connection
      ->transactionManager()
      ->addPostTransactionCallback([
      $this,
      'rootTransactionCallback',
    ]);
    $this->insertRow('row');
    $this->assertNull($this->postTransactionCallbackAction);
    // Callbacks are processed only when destructing the transaction.
    // Executing a DDL statement is not sufficient itself.
    // We cannot use truncate here, since it has protective code to fall back
    // to a transactional delete when in transaction. We drop an unrelated
    // table instead.
    $this->connection
      ->schema()
      ->dropTable('test_people');
    $this->assertNull($this->postTransactionCallbackAction);
    $this->assertRowAbsent('rtcCommit');
    $this->assertRowAbsent('rtcRollback');
    $this->assertRowPresent('row');
    // Callbacks are processed only when destructing the transaction.
    // Executing the rollback is not sufficient by itself.
    $transaction->rollBack();
    $this->assertNull($this->postTransactionCallbackAction);
    $this->assertRowAbsent('rtcCommit');
    $this->assertRowAbsent('rtcRollback');
    $this->assertRowAbsent('row');
    // Destruct the transaction.
    unset($transaction);
    // The post-transaction callback should now have inserted a 'rtcRollback'
    // row.
    $this->assertSame('rtcRollback', $this->postTransactionCallbackAction);
    $this->assertRowAbsent('rtcCommit');
    $this->assertRowPresent('rtcRollback');
    $this->assertRowAbsent('row');
  }
  
  /**
   * Tests post-transaction rollback failure after a DDL statement.
   *
   * For database servers that support transactional DDL, a rollback of a
   * transaction including DDL statements is not possible, since a commit
   * happened already. We cannot decide what should be the status of the
   * callback, an exception is thrown.
   */
  public function testRootTransactionEndCallbackFailureUponDdlAndRollbackForNonTransactionalDdlDatabase() : void {
    if ($this->connection
      ->supportsTransactionalDDL()) {
      $this->markTestSkipped('This test only works for database that do not support transactional DDL.');
    }
    $transaction = $this->createRootTransaction('', FALSE);
    $this->connection
      ->transactionManager()
      ->addPostTransactionCallback([
      $this,
      'rootTransactionCallback',
    ]);
    $this->insertRow('row');
    $this->assertNull($this->postTransactionCallbackAction);
    // Callbacks are processed only when destructing the transaction.
    // Executing a DDL statement is not sufficient itself.
    // We cannot use truncate here, since it has protective code to fall back
    // to a transactional delete when in transaction. We drop an unrelated
    // table instead.
    $this->connection
      ->schema()
      ->dropTable('test_people');
    $this->assertNull($this->postTransactionCallbackAction);
    $this->assertRowAbsent('rtcCommit');
    $this->assertRowAbsent('rtcRollback');
    $this->assertRowPresent('row');
    set_error_handler(static function (int $errno, string $errstr) : bool {
      throw new \ErrorException($errstr);
    });
    try {
      $transaction->rollBack();
    } catch (\ErrorException $e) {
      $this->assertSame('Transaction::rollBack() failed because of a prior execution of a DDL statement.', $e->getMessage());
    } finally {
      restore_error_handler();
    }
    unset($transaction);
    // The post-transaction callback should now have inserted a 'rtcRollback'
    // row.
    $this->assertSame('rtcRollback', $this->postTransactionCallbackAction);
    $this->assertRowAbsent('rtcCommit');
    $this->assertRowPresent('rtcRollback');
    $manager = $this->connection
      ->transactionManager();
    $this->assertSame(0, $manager->stackDepth());
    $reflectedTransactionState = new \ReflectionMethod($manager, 'getConnectionTransactionState');
    $this->assertSame(ClientConnectionTransactionState::RollbackFailed, $reflectedTransactionState->invoke($manager));
    $this->assertRowPresent('row');
  }
  
  /**
   * A post-transaction callback for testing purposes.
   */
  public function rootTransactionCallback(bool $success) : void {
    $this->postTransactionCallbackAction = $success ? 'rtcCommit' : 'rtcRollback';
    $this->insertRow($this->postTransactionCallbackAction);
  }
  
  /**
   * Tests TransactionManager failure.
   */
  public function testTransactionManagerFailureOnPendingStackItems() : void {
    $connectionInfo = Database::getConnectionInfo();
    Database::addConnectionInfo('default', 'test_fail', $connectionInfo['default']);
    $testConnection = Database::getConnection('test_fail');
    // Add a fake item to the stack.
    $manager = $testConnection->transactionManager();
    $reflectionMethod = new \ReflectionMethod($manager, 'addStackItem');
    $reflectionMethod->invoke($manager, 'bar', new StackItem('qux', StackItemType::Root));
    // Ensure transaction state can be determined during object destruction.
    // This is necessary for the test to pass when xdebug.mode has the 'develop'
    // option enabled.
    $reflectionProperty = new \ReflectionProperty(TransactionManagerBase::class, 'connectionTransactionState');
    $reflectionProperty->setValue($manager, ClientConnectionTransactionState::Active);
    // Ensure that __destruct() results in an assertion error. Note that this
    // will normally be called by PHP during the object's destruction but Drupal
    // will commit all transactions when a database is closed thereby making
    // this impossible to test unless it is called directly.
    try {
      $manager->__destruct();
      $this->fail("Expected AssertionError error not thrown");
    } catch (\AssertionError $e) {
      $this->assertStringStartsWith('Transaction $stack was not empty. Active stack: bar\\qux', $e->getMessage());
    }
    // Clean up.
    $reflectionProperty = new \ReflectionProperty(TransactionManagerBase::class, 'stack');
    $reflectionProperty->setValue($manager, []);
    unset($testConnection);
    Database::closeConnection('test_fail');
  }
  
  /**
   * Tests that mocking transactions works fine.
   */
  public function testMockTransaction() : void {
    $connection = $this->getMockBuilder(Connection::class)
      ->disableOriginalConstructor()
      ->getMock();
    $this->getMockBuilder(Transaction::class)
      ->setConstructorArgs([
      $connection,
      '',
      '',
    ])
      ->getMock();
    $this->assertTrue(TRUE);
  }

}