Add support for table locking statements and transaction savepoints (#221)

This PR includes the following changes:

- Add support for `LOCK` and `UNLOCK` statements.
- Add support for transaction savepoints (`SAVEPOINT`, `ROLLBACK TO`,
`RELEASE SAVEPOINT`)
- Improve verification of internal identifier names

Author: JanJakes

tests/WP_SQLite_Driver_Tests.php

@@ -4144,27 +4144,27 @@ public function getReservedPrefixTestData(): array {
 		return array(
 			array(
 				'SELECT * FROM _wp_sqlite_t',
-				"Invalid identifier `_wp_sqlite_t`, prefix '_wp_sqlite_' is reserved",
+				"Invalid identifier '_wp_sqlite_t', prefix '_wp_sqlite_' is reserved",
 			),
 			array(
 				'SELECT _wp_sqlite_t FROM t',
-				"Invalid identifier `_wp_sqlite_t`, prefix '_wp_sqlite_' is reserved",
+				"Invalid identifier '_wp_sqlite_t', prefix '_wp_sqlite_' is reserved",
 			),
 			array(
 				'SELECT t._wp_sqlite_t FROM t',
-				"Invalid identifier `t`.`_wp_sqlite_t`, prefix '_wp_sqlite_' is reserved",
+				"Invalid identifier '_wp_sqlite_t', prefix '_wp_sqlite_' is reserved",
 			),
 			array(
 				'CREATE TABLE _wp_sqlite_t (id INT)',
-				"Invalid identifier `_wp_sqlite_t`, prefix '_wp_sqlite_' is reserved",
+				"Invalid identifier '_wp_sqlite_t', prefix '_wp_sqlite_' is reserved",
 			),
 			array(
 				'ALTER TABLE _wp_sqlite_t ADD COLUMN name TEXT',
-				"Invalid identifier `_wp_sqlite_t`, prefix '_wp_sqlite_' is reserved",
+				"Invalid identifier '_wp_sqlite_t', prefix '_wp_sqlite_' is reserved",
 			),
 			array(
 				'DROP TABLE _wp_sqlite_t',
-				"Invalid identifier `_wp_sqlite_t`, prefix '_wp_sqlite_' is reserved",
+				"Invalid identifier '_wp_sqlite_t', prefix '_wp_sqlite_' is reserved",
 			),
 		);
 	}
@@ -6238,4 +6238,94 @@ public function testUserVariables(): void {
 		$result = $this->assertQuery( 'SELECT @my_var' );
 		$this->assertEquals( 3, $result[0]->{'@my_var'} );
 	}
+
+	public function testLockingStatements(): void {
+		$this->assertQuery( 'CREATE TABLE t (id INT)' );
+
+		// When there is no lock, UNLOCK statement shouldn't fail.
+		$this->assertQuery( 'UNLOCK TABLES' );
+
+		// READ LOCK.
+		$this->assertQuery( 'LOCK TABLES t READ' );
+		$this->assertQuery( 'UNLOCK TABLES' );
+
+		// WRITE LOCK.
+		$this->assertQuery( 'LOCK TABLES t WRITE' );
+		$this->assertQuery( 'UNLOCK TABLES' );
+
+		// LOCK inside a transaction.
+		$this->assertQuery( 'BEGIN' );
+		$this->assertQuery( 'LOCK TABLES t WRITE' );
+		$this->assertQuery( 'UNLOCK TABLES' );
+		$this->assertQuery( 'COMMIT' );
+
+		// Transaction inside LOCK statements.
+		$this->assertQuery( 'LOCK TABLES t WRITE' );
+		$this->assertQuery( 'BEGIN' );
+		$this->assertQuery( 'COMMIT' );
+		$this->assertQuery( 'UNLOCK TABLES' );
+	}
+
+	public function testLockNonExistentTableForRead(): void {
+		$this->expectException( 'WP_SQLite_Driver_Exception' );
+		$this->expectExceptionMessage( "Table 'wp.t' doesn't exist" );
+		$this->assertQuery( 'LOCK TABLES t READ' );
+	}
+
+	public function testLockNonExistentTableForWrite(): void {
+		$this->expectException( 'WP_SQLite_Driver_Exception' );
+		$this->expectExceptionMessage( "Table 'wp.t' doesn't exist" );
+		$this->assertQuery( 'LOCK TABLES t WRITE' );
+	}
+
+	public function testLockMultipleWithNonExistentTable(): void {
+		$this->assertQuery( 'CREATE TABLE t1 (id INT)' );
+		$this->assertQuery( 'CREATE TABLE t3 (id INT)' );
+
+		$this->expectException( 'WP_SQLite_Driver_Exception' );
+		$this->expectExceptionMessage( "Table 'wp.t2' doesn't exist" );
+		$this->assertQuery( 'LOCK TABLES t1 READ, t2 READ, t3 WRITE' );
+	}
+
+	public function testLockTemporaryTables(): void {
+		$this->assertQuery( 'CREATE TEMPORARY TABLE t1 (id INT)' );
+		$this->assertQuery( 'CREATE TABLE t2 (id INT)' );
+		$this->assertQuery( 'CREATE TEMPORARY TABLE t3 (id INT)' );
+		$this->assertQuery( 'LOCK TABLES t1 READ, t2 READ, t3 WRITE' );
+		$this->assertQuery( 'UNLOCK TABLES' );
+	}
+
+	public function testTransactionSavepoints(): void {
+		$this->assertQuery( 'CREATE TABLE t (id INT)' );
+
+		$this->assertQuery( 'BEGIN' );
+		$this->assertQuery( 'INSERT INTO t (id) VALUES (1)' );
+		$result = $this->assertQuery( 'SELECT * FROM t' );
+		$this->assertSame( array( '1' ), (array) array_column( $result, 'id' ) );
+
+		$this->assertQuery( 'SAVEPOINT sp1' );
+		$this->assertQuery( 'INSERT INTO t (id) VALUES (2)' );
+		$result = $this->assertQuery( 'SELECT * FROM t' );
+		$this->assertSame( array( '1', '2' ), (array) array_column( $result, 'id' ) );
+
+		$this->assertQuery( 'SAVEPOINT sp2' );
+		$this->assertQuery( 'INSERT INTO t (id) VALUES (3)' );
+		$result = $this->assertQuery( 'SELECT * FROM t' );
+		$this->assertSame( array( '1', '2', '3' ), (array) array_column( $result, 'id' ) );
+
+		$this->assertQuery( 'ROLLBACK TO SAVEPOINT sp1' );
+		$result = $this->assertQuery( 'SELECT * FROM t' );
+		$this->assertSame( array( '1' ), (array) array_column( $result, 'id' ) );
+
+		$this->assertQuery( 'RELEASE SAVEPOINT sp1' );
+		$this->assertQuery( 'ROLLBACK' );
+		$result = $this->assertQuery( 'SELECT * FROM t' );
+		$this->assertSame( array(), (array) array_column( $result, 'id' ) );
+	}
+
+	public function testRollbackNonExistentTransactionSavepoint(): void {
+		$this->expectException( 'WP_SQLite_Driver_Exception' );
+		$this->expectExceptionMessage( 'no such savepoint: sp1' );
+		$this->assertQuery( 'ROLLBACK TO SAVEPOINT sp1' );
+	}
 }