import XCTest
import GRDB

class TruncateOptimizationTests: GRDBTestCase {
    // https://www.sqlite.org/c3ref/update_hook.html
    //
    // > In the current implementation, the update hook is not invoked [...]
    // > when rows are deleted using the truncate optimization.
    //
    // https://www.sqlite.org/lang_delete.html#truncateopt
    //
    // > When the WHERE is omitted from a DELETE statement and the table
    // > being deleted has no triggers, SQLite uses an optimization to erase
    // > the entire table content without having to visit each row of the
    // > table individually.
    //
    // We  will thus test that the truncate optimization does not prevent
    // transaction observers from observing individual deletions.
    //
    // But that's not enough: preventing the truncate optimization requires GRDB
    // to fiddle with sqlite3_set_authorizer. When badly done, this can prevent
    // DROP TABLE statements from dropping tables. SQLite3 authorizers are
    // invoked during both compilation and execution of SQL statements. We will
    // thus test that DROP TABLE statements perform as expected when compilation
    // and execution are grouped, and when they are performed separately.

    class DeletionObserver : TransactionObserver {
        private var notify: ([String: Int]) -> Void
        private var deletionEvents: [String: Int] = [:]
        
        // Notifies table names with the number of deleted rows
        init(_ notify: @escaping ([String: Int]) -> Void) {
            self.notify = notify
        }
        
        func observes(eventsOfKind eventKind: DatabaseEventKind) -> Bool { true }
        
        func databaseDidChange(with event: DatabaseEvent) {
            if case .delete = event.kind {
                deletionEvents[event.tableName, default: 0] += 1
            }
        }
        
        func databaseDidCommit(_ db: Database) {
            if !deletionEvents.isEmpty {
                notify(deletionEvents)
            }
            deletionEvents = [:]
        }
        
        func databaseDidRollback(_ db: Database) {
            deletionEvents = [:]
        }
    }
    
    class UniversalObserver : TransactionObserver {
        func observes(eventsOfKind eventKind: DatabaseEventKind) -> Bool { true }
        func databaseDidChange(with event: DatabaseEvent) { }
        func databaseDidCommit(_ db: Database) { }
        func databaseDidRollback(_ db: Database) { }
    }
    
    func testExecuteDelete() throws {
        let dbQueue = try makeDatabaseQueue()
        
        var deletionEvents: [[String: Int]] = []
        let observer = DeletionObserver { deletionEvents.append($0) }
        dbQueue.add(transactionObserver: observer, extent: .databaseLifetime)
        
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            deletionEvents = []
            try db.execute(sql: "DELETE FROM t")
            XCTAssertEqual(deletionEvents.count, 1)
            XCTAssertEqual(deletionEvents[0], ["t": 2])
            
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            deletionEvents = []
            try db.execute(sql: "DELETE FROM t")
            XCTAssertEqual(deletionEvents.count, 1)
            XCTAssertEqual(deletionEvents[0], ["t": 1])
        }
    }
    
    func testExecuteDeleteCaseSensitivity() throws {
        let dbQueue = try makeDatabaseQueue()
        
        class DeletionObserver : TransactionObserver {
            var deletionCount = 0
            
            func observes(eventsOfKind eventKind: DatabaseEventKind) -> Bool {
                if case .delete(tableName: "pLaYeR") = eventKind {
                    return true
                } else {
                    return false
                }
            }
            
            func databaseDidChange(with event: DatabaseEvent) {
                if case .delete = event.kind {
                    deletionCount += 1
                }
            }
            
            func databaseDidCommit(_ db: Database) { }
            func databaseDidRollback(_ db: Database) { }
        }

        let observer = DeletionObserver()
        dbQueue.add(transactionObserver: observer, extent: .databaseLifetime)
        
        try dbQueue.writeWithoutTransaction { db in
            observer.deletionCount = 0
            try db.execute(sql: "CREATE TABLE pLaYeR(a)")
            try db.execute(sql: "INSERT INTO pLaYeR VALUES (NULL)")
            try db.execute(sql: "INSERT INTO pLaYeR VALUES (NULL)")
            try db.execute(sql: "DELETE FROM pLaYeR")
            XCTAssertEqual(observer.deletionCount, 2)
            
            observer.deletionCount = 0
            try db.execute(sql: "INSERT INTO pLaYeR VALUES (NULL)")
            try db.execute(sql: "DELETE FROM PLAYER")
            XCTAssertEqual(observer.deletionCount, 1)
            
            observer.deletionCount = 0
            try db.execute(sql: "INSERT INTO pLaYeR VALUES (NULL)")
            try db.execute(sql: "DELETE FROM player")
            XCTAssertEqual(observer.deletionCount, 1)
        }
    }
    
    func testExecuteDeleteWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        
        var deletionEvents: [[String: Int]] = []
        let observer = DeletionObserver { deletionEvents.append($0) }
        dbQueue.add(transactionObserver: observer, extent: .databaseLifetime)
        
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            let deleteStatement = try db.makeStatement(sql: "DELETE FROM t")
            
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            deletionEvents = []
            try deleteStatement.execute()
            XCTAssertEqual(deletionEvents.count, 1)
            XCTAssertEqual(deletionEvents[0], ["t": 2])
            
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            deletionEvents = []
            try deleteStatement.execute()
            XCTAssertEqual(deletionEvents.count, 1)
            XCTAssertEqual(deletionEvents[0], ["t": 1])
        }
    }
    
    func testExecuteDeleteWithCachedPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        
        var deletionEvents: [[String: Int]] = []
        
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.cachedStatement(sql: "DELETE FROM t").execute()
            
            // Start observing after statement has been cached: it does not
            // prevent the truncate optimization.
            let observer = DeletionObserver { deletionEvents.append($0) }
            db.add(transactionObserver: observer, extent: .databaseLifetime)

            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            deletionEvents = []
            // This must be a recompiled statement, so that the truncate
            // optimization is prevented.
            try db.cachedStatement(sql: "DELETE FROM t").execute()
            XCTAssertEqual(deletionEvents.count, 1)
            XCTAssertEqual(deletionEvents[0], ["t": 2])
            
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            deletionEvents = []
            try db.cachedStatement(sql: "DELETE FROM t").execute()
            XCTAssertEqual(deletionEvents.count, 1)
            XCTAssertEqual(deletionEvents[0], ["t": 1])
        }
    }
    
    func testDropTable() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.tableExists("t"))
            try db.execute(sql: "DROP TABLE t") // compile + execute
            try XCTAssertFalse(db.tableExists("t"))
        }
    }
    
    func testObservedDropTable() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.tableExists("t"))
            try db.execute(sql: "DROP TABLE t") // compile + execute
            try XCTAssertFalse(db.tableExists("t"))
        }
    }

    func testDropTableWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.tableExists("t"))
            let dropStatement = try db.makeStatement(sql: "DROP TABLE t") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.tableExists("t"))
        }
    }

    func testObservedDropTableWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.tableExists("t"))
            let dropStatement = try db.makeStatement(sql: "DROP TABLE t") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.tableExists("t"))
        }
    }

    func testDropTemporaryTable() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TEMPORARY TABLE t(a)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.tableExists("t"))
            try db.execute(sql: "DROP TABLE t") // compile + execute
            try XCTAssertFalse(db.tableExists("t"))
        }
    }
    
    func testObservedDropTemporaryTable() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TEMPORARY TABLE t(a)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.tableExists("t"))
            try db.execute(sql: "DROP TABLE t") // compile + execute
            try XCTAssertFalse(db.tableExists("t"))
        }
    }
    
    func testDropTemporaryTableWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TEMPORARY TABLE t(a)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.tableExists("t"))
            let dropStatement = try db.makeStatement(sql: "DROP TABLE t") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.tableExists("t"))
        }
    }
    
    func testObservedDropTemporaryTableWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TEMPORARY TABLE t(a)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.tableExists("t"))
            let dropStatement = try db.makeStatement(sql: "DROP TABLE t") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.tableExists("t"))
        }
    }
    
    func testDropVirtualTable() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE VIRTUAL TABLE t USING fts3(a)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.tableExists("t"))
            try db.execute(sql: "DROP TABLE t") // compile + execute
            try XCTAssertFalse(db.tableExists("t"))
        }
    }
    
    func testObservedDropVirtualTable() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE VIRTUAL TABLE t USING fts3(a)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.tableExists("t"))
            try db.execute(sql: "DROP TABLE t") // compile + execute
            try XCTAssertFalse(db.tableExists("t"))
        }
    }
    
    func testDropVirtualTableWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE VIRTUAL TABLE t USING fts3(a)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.tableExists("t"))
            let dropStatement = try db.makeStatement(sql: "DROP TABLE t") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.tableExists("t"))
        }
    }
    
    func testObservedDropVirtualTableWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE VIRTUAL TABLE t USING fts3(a)")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.tableExists("t"))
            let dropStatement = try db.makeStatement(sql: "DROP TABLE t") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.tableExists("t"))
        }
    }
    
    func testDropView() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE VIEW v AS SELECT * FROM t")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.viewExists("v"))
            try db.execute(sql: "DROP VIEW v") // compile + execute
            try XCTAssertFalse(db.viewExists("v"))
        }
    }
    
    func testObservedDropView() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE VIEW v AS SELECT * FROM t")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.viewExists("v"))
            try db.execute(sql: "DROP VIEW v") // compile + execute
            try XCTAssertFalse(db.viewExists("v"))
        }
    }
    
    func testDropViewWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE VIEW v AS SELECT * FROM t")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.viewExists("v"))
            let dropStatement = try db.makeStatement(sql: "DROP VIEW v") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.viewExists("v"))
        }
    }
    
    func testObservedDropViewWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE VIEW v AS SELECT * FROM t")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.viewExists("v"))
            let dropStatement = try db.makeStatement(sql: "DROP VIEW v") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.viewExists("v"))
        }
    }
    
    func testDropTemporaryView() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE TEMPORARY VIEW v AS SELECT * FROM t")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.viewExists("v"))
            try db.execute(sql: "DROP VIEW v") // compile + execute
            try XCTAssertFalse(db.viewExists("v"))
        }
    }
    
    func testObservedDropTemporaryView() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE TEMPORARY VIEW v AS SELECT * FROM t")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.viewExists("v"))
            try db.execute(sql: "DROP VIEW v") // compile + execute
            try XCTAssertFalse(db.viewExists("v"))
        }
    }
    
    func testDropTemporaryViewWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE TEMPORARY VIEW v AS SELECT * FROM t")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.viewExists("v"))
            let dropStatement = try db.makeStatement(sql: "DROP VIEW v") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.viewExists("v"))
        }
    }
    
    func testObservedDropTemporaryViewWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE TEMPORARY VIEW v AS SELECT * FROM t")
            try db.execute(sql: "INSERT INTO t VALUES (NULL)")
            try XCTAssertTrue(db.viewExists("v"))
            let dropStatement = try db.makeStatement(sql: "DROP VIEW v") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.viewExists("v"))
        }
    }
    
    func testDropIndex() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE INDEX i ON t(a)")
            try XCTAssertFalse(db.indexes(on: "t").isEmpty)
            try db.execute(sql: "DROP INDEX i") // compile + execute
            try XCTAssertTrue(db.indexes(on: "t").isEmpty)
        }
    }
    
    func testObservedDropIndex() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE INDEX i ON t(a)")
            try XCTAssertFalse(db.indexes(on: "t").isEmpty)
            try db.execute(sql: "DROP INDEX i") // compile + execute
            try XCTAssertTrue(db.indexes(on: "t").isEmpty)
        }
    }
    
    func testDropIndexViewWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE INDEX i ON t(a)")
            try db.execute(sql: "INSERT INTO t VALUES (1)")
            try XCTAssertFalse(db.indexes(on: "t").isEmpty)
            let dropStatement = try db.makeStatement(sql: "DROP INDEX i") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertTrue(db.indexes(on: "t").isEmpty)
        }
    }
    
    func testObservedDropIndexViewWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE INDEX i ON t(a)")
            try db.execute(sql: "INSERT INTO t VALUES (1)")
            try XCTAssertFalse(db.indexes(on: "t").isEmpty)
            let dropStatement = try db.makeStatement(sql: "DROP INDEX i") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertTrue(db.indexes(on: "t").isEmpty)
        }
    }
    
    func testDropTemporaryIndex() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TEMPORARY TABLE t(a)")
            try db.execute(sql: "CREATE INDEX i ON t(a)")
            try XCTAssertFalse(db.indexes(on: "t").isEmpty)
            try db.execute(sql: "DROP INDEX i") // compile + execute
            try XCTAssertTrue(db.indexes(on: "t").isEmpty)
        }
    }
    
    func testObservedDropTemporaryIndex() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TEMPORARY TABLE t(a)")
            try db.execute(sql: "CREATE INDEX i ON t(a)")
            try XCTAssertFalse(db.indexes(on: "t").isEmpty)
            try db.execute(sql: "DROP INDEX i") // compile + execute
            try XCTAssertTrue(db.indexes(on: "t").isEmpty)
        }
    }
    
    func testDropTemporaryIndexViewWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TEMPORARY TABLE t(a)")
            try db.execute(sql: "CREATE INDEX i ON t(a)")
            try db.execute(sql: "INSERT INTO t VALUES (1)")
            try XCTAssertFalse(db.indexes(on: "t").isEmpty)
            let dropStatement = try db.makeStatement(sql: "DROP INDEX i") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertTrue(db.indexes(on: "t").isEmpty)
        }
    }
    
    func testObservedDropTemporaryIndexViewWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TEMPORARY TABLE t(a)")
            try db.execute(sql: "CREATE INDEX i ON t(a)")
            try db.execute(sql: "INSERT INTO t VALUES (1)")
            try XCTAssertFalse(db.indexes(on: "t").isEmpty)
            let dropStatement = try db.makeStatement(sql: "DROP INDEX i") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertTrue(db.indexes(on: "t").isEmpty)
        }
    }
    
    func testDropTrigger() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE TRIGGER r INSERT ON t BEGIN DELETE FROM t; END")
            try XCTAssertTrue(db.triggerExists("r"))
            try db.execute(sql: "DROP TRIGGER r") // compile + execute
            try XCTAssertFalse(db.triggerExists("r"))
        }
    }
    
    func testObservedDropTrigger() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE TRIGGER r INSERT ON t BEGIN DELETE FROM t; END")
            try XCTAssertTrue(db.triggerExists("r"))
            try db.execute(sql: "DROP TRIGGER r") // compile + execute
            try XCTAssertFalse(db.triggerExists("r"))
        }
    }
    
    func testDropTriggerWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE TRIGGER r INSERT ON t BEGIN DELETE FROM t; END")
            try XCTAssertTrue(db.triggerExists("r"))
            let dropStatement = try db.makeStatement(sql: "DROP TRIGGER r") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.triggerExists("r"))
        }
    }
    
    func testObservedDropTriggerWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE TRIGGER r INSERT ON t BEGIN DELETE FROM t; END")
            try XCTAssertTrue(db.triggerExists("r"))
            let dropStatement = try db.makeStatement(sql: "DROP TRIGGER r") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.triggerExists("r"))
        }
    }
    
    func testDropTemporaryTrigger() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE TEMPORARY TRIGGER r INSERT ON t BEGIN DELETE FROM t; END")
            try XCTAssertTrue(db.triggerExists("r"))
            try db.execute(sql: "DROP TRIGGER r") // compile + execute
            try XCTAssertFalse(db.triggerExists("r"))
        }
    }
    
    func testObservedDropTemporaryTrigger() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE TEMPORARY TRIGGER r INSERT ON t BEGIN DELETE FROM t; END")
            try XCTAssertTrue(db.triggerExists("r"))
            try db.execute(sql: "DROP TRIGGER r") // compile + execute
            try XCTAssertFalse(db.triggerExists("r"))
        }
    }
    
    func testDropTemporaryTriggerWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE TEMPORARY TRIGGER r INSERT ON t BEGIN DELETE FROM t; END")
            try XCTAssertTrue(db.triggerExists("r"))
            let dropStatement = try db.makeStatement(sql: "DROP TRIGGER r") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.triggerExists("r"))
        }
    }
    
    func testObservedDropTemporaryTriggerWithPreparedStatement() throws {
        let dbQueue = try makeDatabaseQueue()
        dbQueue.add(transactionObserver: UniversalObserver(), extent: .databaseLifetime)
        try dbQueue.writeWithoutTransaction { db in
            try db.execute(sql: "CREATE TABLE t(a)")
            try db.execute(sql: "CREATE TEMPORARY TRIGGER r INSERT ON t BEGIN DELETE FROM t; END")
            try XCTAssertTrue(db.triggerExists("r"))
            let dropStatement = try db.makeStatement(sql: "DROP TRIGGER r") // compile...
            try dropStatement.execute() // ... then execute
            try XCTAssertFalse(db.triggerExists("r"))
        }
    }
}