[3.10] gh-79579: Improve DML query detection in sqlite3 (GH-93623) (#93801)

The fix involves using pysqlite_check_remaining_sql(), not only to check
for multiple statements, but now also to strip leading comments and
whitespace from SQL statements, so we can improve DML query detection.

pysqlite_check_remaining_sql() is renamed lstrip_sql(), to more
accurately reflect its function, and hardened to handle more SQL comment
corner cases.

(cherry picked from commit 46740073ef32bf83964c39609c7a7a4772c51ce3)

3 files changed, 1939 insertions, 75 deletions

diff --git a/Lib/test/test_sqlite3/test_dbapi.py b/Lib/test/test_sqlite3/test_dbapi.py
new file mode 100644
index 0000000..18e84e9
--- /dev/null
+++ b/Lib/test/test_sqlite3/test_dbapi.py
@@ -0,0 +1,1892 @@
+# pysqlite2/test/dbapi.py: tests for DB-API compliance
+#
+# Copyright (C) 2004-2010 Gerhard Häring <gh@ghaering.de>
+#
+# This file is part of pysqlite.
+#
+# This software is provided 'as-is', without any express or implied
+# warranty.  In no event will the authors be held liable for any damages
+# arising from the use of this software.
+#
+# Permission is granted to anyone to use this software for any purpose,
+# including commercial applications, and to alter it and redistribute it
+# freely, subject to the following restrictions:
+#
+# 1. The origin of this software must not be misrepresented; you must not
+#    claim that you wrote the original software. If you use this software
+#    in a product, an acknowledgment in the product documentation would be
+#    appreciated but is not required.
+# 2. Altered source versions must be plainly marked as such, and must not be
+#    misrepresented as being the original software.
+# 3. This notice may not be removed or altered from any source distribution.
+
+import contextlib
+import os
+import sqlite3 as sqlite
+import subprocess
+import sys
+import threading
+import unittest
+import urllib.parse
+
+from test.support import SHORT_TIMEOUT, check_disallow_instantiation
+from test.support import threading_helper
+from _testcapi import INT_MAX, ULLONG_MAX
+from os import SEEK_SET, SEEK_CUR, SEEK_END
+from test.support.os_helper import TESTFN, TESTFN_UNDECODABLE, unlink, temp_dir, FakePath
+
+
+# Helper for temporary memory databases
+def memory_database(*args, **kwargs):
+    cx = sqlite.connect(":memory:", *args, **kwargs)
+    return contextlib.closing(cx)
+
+
+# Temporarily limit a database connection parameter
+@contextlib.contextmanager
+def cx_limit(cx, category=sqlite.SQLITE_LIMIT_SQL_LENGTH, limit=128):
+    try:
+        _prev = cx.setlimit(category, limit)
+        yield limit
+    finally:
+        cx.setlimit(category, _prev)
+
+
+class ModuleTests(unittest.TestCase):
+    def test_api_level(self):
+        self.assertEqual(sqlite.apilevel, "2.0",
+                         "apilevel is %s, should be 2.0" % sqlite.apilevel)
+
+    def test_deprecated_version(self):
+        msg = "deprecated and will be removed in Python 3.14"
+        for attr in "version", "version_info":
+            with self.subTest(attr=attr):
+                with self.assertWarnsRegex(DeprecationWarning, msg) as cm:
+                    getattr(sqlite, attr)
+                self.assertEqual(cm.filename,  __file__)
+                with self.assertWarnsRegex(DeprecationWarning, msg) as cm:
+                    getattr(sqlite.dbapi2, attr)
+                self.assertEqual(cm.filename,  __file__)
+
+    def test_thread_safety(self):
+        self.assertIn(sqlite.threadsafety, {0, 1, 3},
+                      "threadsafety is %d, should be 0, 1 or 3" %
+                      sqlite.threadsafety)
+
+    def test_param_style(self):
+        self.assertEqual(sqlite.paramstyle, "qmark",
+                         "paramstyle is '%s', should be 'qmark'" %
+                         sqlite.paramstyle)
+
+    def test_warning(self):
+        self.assertTrue(issubclass(sqlite.Warning, Exception),
+                     "Warning is not a subclass of Exception")
+
+    def test_error(self):
+        self.assertTrue(issubclass(sqlite.Error, Exception),
+                        "Error is not a subclass of Exception")
+
+    def test_interface_error(self):
+        self.assertTrue(issubclass(sqlite.InterfaceError, sqlite.Error),
+                        "InterfaceError is not a subclass of Error")
+
+    def test_database_error(self):
+        self.assertTrue(issubclass(sqlite.DatabaseError, sqlite.Error),
+                        "DatabaseError is not a subclass of Error")
+
+    def test_data_error(self):
+        self.assertTrue(issubclass(sqlite.DataError, sqlite.DatabaseError),
+                        "DataError is not a subclass of DatabaseError")
+
+    def test_operational_error(self):
+        self.assertTrue(issubclass(sqlite.OperationalError, sqlite.DatabaseError),
+                        "OperationalError is not a subclass of DatabaseError")
+
+    def test_integrity_error(self):
+        self.assertTrue(issubclass(sqlite.IntegrityError, sqlite.DatabaseError),
+                        "IntegrityError is not a subclass of DatabaseError")
+
+    def test_internal_error(self):
+        self.assertTrue(issubclass(sqlite.InternalError, sqlite.DatabaseError),
+                        "InternalError is not a subclass of DatabaseError")
+
+    def test_programming_error(self):
+        self.assertTrue(issubclass(sqlite.ProgrammingError, sqlite.DatabaseError),
+                        "ProgrammingError is not a subclass of DatabaseError")
+
+    def test_not_supported_error(self):
+        self.assertTrue(issubclass(sqlite.NotSupportedError,
+                                   sqlite.DatabaseError),
+                        "NotSupportedError is not a subclass of DatabaseError")
+
+    def test_module_constants(self):
+        consts = [
+            "SQLITE_ABORT",
+            "SQLITE_ALTER_TABLE",
+            "SQLITE_ANALYZE",
+            "SQLITE_ATTACH",
+            "SQLITE_AUTH",
+            "SQLITE_BUSY",
+            "SQLITE_CANTOPEN",
+            "SQLITE_CONSTRAINT",
+            "SQLITE_CORRUPT",
+            "SQLITE_CREATE_INDEX",
+            "SQLITE_CREATE_TABLE",
+            "SQLITE_CREATE_TEMP_INDEX",
+            "SQLITE_CREATE_TEMP_TABLE",
+            "SQLITE_CREATE_TEMP_TRIGGER",
+            "SQLITE_CREATE_TEMP_VIEW",
+            "SQLITE_CREATE_TRIGGER",
+            "SQLITE_CREATE_VIEW",
+            "SQLITE_CREATE_VTABLE",
+            "SQLITE_DELETE",
+            "SQLITE_DENY",
+            "SQLITE_DETACH",
+            "SQLITE_DONE",
+            "SQLITE_DROP_INDEX",
+            "SQLITE_DROP_TABLE",
+            "SQLITE_DROP_TEMP_INDEX",
+            "SQLITE_DROP_TEMP_TABLE",
+            "SQLITE_DROP_TEMP_TRIGGER",
+            "SQLITE_DROP_TEMP_VIEW",
+            "SQLITE_DROP_TRIGGER",
+            "SQLITE_DROP_VIEW",
+            "SQLITE_DROP_VTABLE",
+            "SQLITE_EMPTY",
+            "SQLITE_ERROR",
+            "SQLITE_FORMAT",
+            "SQLITE_FULL",
+            "SQLITE_FUNCTION",
+            "SQLITE_IGNORE",
+            "SQLITE_INSERT",
+            "SQLITE_INTERNAL",
+            "SQLITE_INTERRUPT",
+            "SQLITE_IOERR",
+            "SQLITE_LOCKED",
+            "SQLITE_MISMATCH",
+            "SQLITE_MISUSE",
+            "SQLITE_NOLFS",
+            "SQLITE_NOMEM",
+            "SQLITE_NOTADB",
+            "SQLITE_NOTFOUND",
+            "SQLITE_OK",
+            "SQLITE_PERM",
+            "SQLITE_PRAGMA",
+            "SQLITE_PROTOCOL",
+            "SQLITE_RANGE",
+            "SQLITE_READ",
+            "SQLITE_READONLY",
+            "SQLITE_REINDEX",
+            "SQLITE_ROW",
+            "SQLITE_SAVEPOINT",
+            "SQLITE_SCHEMA",
+            "SQLITE_SELECT",
+            "SQLITE_TOOBIG",
+            "SQLITE_TRANSACTION",
+            "SQLITE_UPDATE",
+            # Run-time limit categories
+            "SQLITE_LIMIT_LENGTH",
+            "SQLITE_LIMIT_SQL_LENGTH",
+            "SQLITE_LIMIT_COLUMN",
+            "SQLITE_LIMIT_EXPR_DEPTH",
+            "SQLITE_LIMIT_COMPOUND_SELECT",
+            "SQLITE_LIMIT_VDBE_OP",
+            "SQLITE_LIMIT_FUNCTION_ARG",
+            "SQLITE_LIMIT_ATTACHED",
+            "SQLITE_LIMIT_LIKE_PATTERN_LENGTH",
+            "SQLITE_LIMIT_VARIABLE_NUMBER",
+            "SQLITE_LIMIT_TRIGGER_DEPTH",
+        ]
+        if sqlite.sqlite_version_info >= (3, 7, 17):
+            consts += ["SQLITE_NOTICE", "SQLITE_WARNING"]
+        if sqlite.sqlite_version_info >= (3, 8, 3):
+            consts.append("SQLITE_RECURSIVE")
+        if sqlite.sqlite_version_info >= (3, 8, 7):
+            consts.append("SQLITE_LIMIT_WORKER_THREADS")
+        consts += ["PARSE_DECLTYPES", "PARSE_COLNAMES"]
+        # Extended result codes
+        consts += [
+            "SQLITE_ABORT_ROLLBACK",
+            "SQLITE_BUSY_RECOVERY",
+            "SQLITE_CANTOPEN_FULLPATH",
+            "SQLITE_CANTOPEN_ISDIR",
+            "SQLITE_CANTOPEN_NOTEMPDIR",
+            "SQLITE_CORRUPT_VTAB",
+            "SQLITE_IOERR_ACCESS",
+            "SQLITE_IOERR_BLOCKED",
+            "SQLITE_IOERR_CHECKRESERVEDLOCK",
+            "SQLITE_IOERR_CLOSE",
+            "SQLITE_IOERR_DELETE",
+            "SQLITE_IOERR_DELETE_NOENT",
+            "SQLITE_IOERR_DIR_CLOSE",
+            "SQLITE_IOERR_DIR_FSYNC",
+            "SQLITE_IOERR_FSTAT",
+            "SQLITE_IOERR_FSYNC",
+            "SQLITE_IOERR_LOCK",
+            "SQLITE_IOERR_NOMEM",
+            "SQLITE_IOERR_RDLOCK",
+            "SQLITE_IOERR_READ",
+            "SQLITE_IOERR_SEEK",
+            "SQLITE_IOERR_SHMLOCK",
+            "SQLITE_IOERR_SHMMAP",
+            "SQLITE_IOERR_SHMOPEN",
+            "SQLITE_IOERR_SHMSIZE",
+            "SQLITE_IOERR_SHORT_READ",
+            "SQLITE_IOERR_TRUNCATE",
+            "SQLITE_IOERR_UNLOCK",
+            "SQLITE_IOERR_WRITE",
+            "SQLITE_LOCKED_SHAREDCACHE",
+            "SQLITE_READONLY_CANTLOCK",
+            "SQLITE_READONLY_RECOVERY",
+        ]
+        if sqlite.sqlite_version_info >= (3, 7, 16):
+            consts += [
+                "SQLITE_CONSTRAINT_CHECK",
+                "SQLITE_CONSTRAINT_COMMITHOOK",
+                "SQLITE_CONSTRAINT_FOREIGNKEY",
+                "SQLITE_CONSTRAINT_FUNCTION",
+                "SQLITE_CONSTRAINT_NOTNULL",
+                "SQLITE_CONSTRAINT_PRIMARYKEY",
+                "SQLITE_CONSTRAINT_TRIGGER",
+                "SQLITE_CONSTRAINT_UNIQUE",
+                "SQLITE_CONSTRAINT_VTAB",
+                "SQLITE_READONLY_ROLLBACK",
+            ]
+        if sqlite.sqlite_version_info >= (3, 7, 17):
+            consts += [
+                "SQLITE_IOERR_MMAP",
+                "SQLITE_NOTICE_RECOVER_ROLLBACK",
+                "SQLITE_NOTICE_RECOVER_WAL",
+            ]
+        if sqlite.sqlite_version_info >= (3, 8, 0):
+            consts += [
+                "SQLITE_BUSY_SNAPSHOT",
+                "SQLITE_IOERR_GETTEMPPATH",
+                "SQLITE_WARNING_AUTOINDEX",
+            ]
+        if sqlite.sqlite_version_info >= (3, 8, 1):
+            consts += ["SQLITE_CANTOPEN_CONVPATH", "SQLITE_IOERR_CONVPATH"]
+        if sqlite.sqlite_version_info >= (3, 8, 2):
+            consts.append("SQLITE_CONSTRAINT_ROWID")
+        if sqlite.sqlite_version_info >= (3, 8, 3):
+            consts.append("SQLITE_READONLY_DBMOVED")
+        if sqlite.sqlite_version_info >= (3, 8, 7):
+            consts.append("SQLITE_AUTH_USER")
+        if sqlite.sqlite_version_info >= (3, 9, 0):
+            consts.append("SQLITE_IOERR_VNODE")
+        if sqlite.sqlite_version_info >= (3, 10, 0):
+            consts.append("SQLITE_IOERR_AUTH")
+        if sqlite.sqlite_version_info >= (3, 14, 1):
+            consts.append("SQLITE_OK_LOAD_PERMANENTLY")
+        if sqlite.sqlite_version_info >= (3, 21, 0):
+            consts += [
+                "SQLITE_IOERR_BEGIN_ATOMIC",
+                "SQLITE_IOERR_COMMIT_ATOMIC",
+                "SQLITE_IOERR_ROLLBACK_ATOMIC",
+            ]
+        if sqlite.sqlite_version_info >= (3, 22, 0):
+            consts += [
+                "SQLITE_ERROR_MISSING_COLLSEQ",
+                "SQLITE_ERROR_RETRY",
+                "SQLITE_READONLY_CANTINIT",
+                "SQLITE_READONLY_DIRECTORY",
+            ]
+        if sqlite.sqlite_version_info >= (3, 24, 0):
+            consts += ["SQLITE_CORRUPT_SEQUENCE", "SQLITE_LOCKED_VTAB"]
+        if sqlite.sqlite_version_info >= (3, 25, 0):
+            consts += ["SQLITE_CANTOPEN_DIRTYWAL", "SQLITE_ERROR_SNAPSHOT"]
+        if sqlite.sqlite_version_info >= (3, 31, 0):
+            consts += [
+                "SQLITE_CANTOPEN_SYMLINK",
+                "SQLITE_CONSTRAINT_PINNED",
+                "SQLITE_OK_SYMLINK",
+            ]
+        if sqlite.sqlite_version_info >= (3, 32, 0):
+            consts += [
+                "SQLITE_BUSY_TIMEOUT",
+                "SQLITE_CORRUPT_INDEX",
+                "SQLITE_IOERR_DATA",
+            ]
+        if sqlite.sqlite_version_info >= (3, 34, 0):
+            consts.append("SQLITE_IOERR_CORRUPTFS")
+        for const in consts:
+            with self.subTest(const=const):
+                self.assertTrue(hasattr(sqlite, const))
+
+    def test_error_code_on_exception(self):
+        err_msg = "unable to open database file"
+        if sys.platform.startswith("win"):
+            err_code = sqlite.SQLITE_CANTOPEN_ISDIR
+        else:
+            err_code = sqlite.SQLITE_CANTOPEN
+
+        with temp_dir() as db:
+            with self.assertRaisesRegex(sqlite.Error, err_msg) as cm:
+                sqlite.connect(db)
+            e = cm.exception
+            self.assertEqual(e.sqlite_errorcode, err_code)
+            self.assertTrue(e.sqlite_errorname.startswith("SQLITE_CANTOPEN"))
+
+    @unittest.skipIf(sqlite.sqlite_version_info <= (3, 7, 16),
+                     "Requires SQLite 3.7.16 or newer")
+    def test_extended_error_code_on_exception(self):
+        with memory_database() as con:
+            with con:
+                con.execute("create table t(t integer check(t > 0))")
+            errmsg = "constraint failed"
+            with self.assertRaisesRegex(sqlite.IntegrityError, errmsg) as cm:
+                con.execute("insert into t values(-1)")
+            exc = cm.exception
+            self.assertEqual(exc.sqlite_errorcode,
+                             sqlite.SQLITE_CONSTRAINT_CHECK)
+            self.assertEqual(exc.sqlite_errorname, "SQLITE_CONSTRAINT_CHECK")
+
+    def test_disallow_instantiation(self):
+        cx = sqlite.connect(":memory:")
+        check_disallow_instantiation(self, type(cx("select 1")))
+        check_disallow_instantiation(self, sqlite.Blob)
+
+    def test_complete_statement(self):
+        self.assertFalse(sqlite.complete_statement("select t"))
+        self.assertTrue(sqlite.complete_statement("create table t(t);"))
+
+
+class ConnectionTests(unittest.TestCase):
+
+    def setUp(self):
+        self.cx = sqlite.connect(":memory:")
+        cu = self.cx.cursor()
+        cu.execute("create table test(id integer primary key, name text)")
+        cu.execute("insert into test(name) values (?)", ("foo",))
+
+    def tearDown(self):
+        self.cx.close()
+
+    def test_commit(self):
+        self.cx.commit()
+
+    def test_commit_after_no_changes(self):
+        """
+        A commit should also work when no changes were made to the database.
+        """
+        self.cx.commit()
+        self.cx.commit()
+
+    def test_rollback(self):
+        self.cx.rollback()
+
+    def test_rollback_after_no_changes(self):
+        """
+        A rollback should also work when no changes were made to the database.
+        """
+        self.cx.rollback()
+        self.cx.rollback()
+
+    def test_cursor(self):
+        cu = self.cx.cursor()
+
+    def test_failed_open(self):
+        YOU_CANNOT_OPEN_THIS = "/foo/bar/bla/23534/mydb.db"
+        with self.assertRaises(sqlite.OperationalError):
+            sqlite.connect(YOU_CANNOT_OPEN_THIS)
+
+    def test_close(self):
+        self.cx.close()
+
+    def test_use_after_close(self):
+        sql = "select 1"
+        cu = self.cx.cursor()
+        res = cu.execute(sql)
+        self.cx.close()
+        self.assertRaises(sqlite.ProgrammingError, res.fetchall)
+        self.assertRaises(sqlite.ProgrammingError, cu.execute, sql)
+        self.assertRaises(sqlite.ProgrammingError, cu.executemany, sql, [])
+        self.assertRaises(sqlite.ProgrammingError, cu.executescript, sql)
+        self.assertRaises(sqlite.ProgrammingError, self.cx.execute, sql)
+        self.assertRaises(sqlite.ProgrammingError,
+                          self.cx.executemany, sql, [])
+        self.assertRaises(sqlite.ProgrammingError, self.cx.executescript, sql)
+        self.assertRaises(sqlite.ProgrammingError,
+                          self.cx.create_function, "t", 1, lambda x: x)
+        self.assertRaises(sqlite.ProgrammingError, self.cx.cursor)
+        with self.assertRaises(sqlite.ProgrammingError):
+            with self.cx:
+                pass
+
+    def test_exceptions(self):
+        # Optional DB-API extension.
+        self.assertEqual(self.cx.Warning, sqlite.Warning)
+        self.assertEqual(self.cx.Error, sqlite.Error)
+        self.assertEqual(self.cx.InterfaceError, sqlite.InterfaceError)
+        self.assertEqual(self.cx.DatabaseError, sqlite.DatabaseError)
+        self.assertEqual(self.cx.DataError, sqlite.DataError)
+        self.assertEqual(self.cx.OperationalError, sqlite.OperationalError)
+        self.assertEqual(self.cx.IntegrityError, sqlite.IntegrityError)
+        self.assertEqual(self.cx.InternalError, sqlite.InternalError)
+        self.assertEqual(self.cx.ProgrammingError, sqlite.ProgrammingError)
+        self.assertEqual(self.cx.NotSupportedError, sqlite.NotSupportedError)
+
+    def test_in_transaction(self):
+        # Can't use db from setUp because we want to test initial state.
+        cx = sqlite.connect(":memory:")
+        cu = cx.cursor()
+        self.assertEqual(cx.in_transaction, False)
+        cu.execute("create table transactiontest(id integer primary key, name text)")
+        self.assertEqual(cx.in_transaction, False)
+        cu.execute("insert into transactiontest(name) values (?)", ("foo",))
+        self.assertEqual(cx.in_transaction, True)
+        cu.execute("select name from transactiontest where name=?", ["foo"])
+        row = cu.fetchone()
+        self.assertEqual(cx.in_transaction, True)
+        cx.commit()
+        self.assertEqual(cx.in_transaction, False)
+        cu.execute("select name from transactiontest where name=?", ["foo"])
+        row = cu.fetchone()
+        self.assertEqual(cx.in_transaction, False)
+
+    def test_in_transaction_ro(self):
+        with self.assertRaises(AttributeError):
+            self.cx.in_transaction = True
+
+    def test_connection_exceptions(self):
+        exceptions = [
+            "DataError",
+            "DatabaseError",
+            "Error",
+            "IntegrityError",
+            "InterfaceError",
+            "NotSupportedError",
+            "OperationalError",
+            "ProgrammingError",
+            "Warning",
+        ]
+        for exc in exceptions:
+            with self.subTest(exc=exc):
+                self.assertTrue(hasattr(self.cx, exc))
+                self.assertIs(getattr(sqlite, exc), getattr(self.cx, exc))
+
+    def test_interrupt_on_closed_db(self):
+        cx = sqlite.connect(":memory:")
+        cx.close()
+        with self.assertRaises(sqlite.ProgrammingError):
+            cx.interrupt()
+
+    def test_interrupt(self):
+        self.assertIsNone(self.cx.interrupt())
+
+    def test_drop_unused_refs(self):
+        for n in range(500):
+            cu = self.cx.execute(f"select {n}")
+            self.assertEqual(cu.fetchone()[0], n)
+
+    def test_connection_limits(self):
+        category = sqlite.SQLITE_LIMIT_SQL_LENGTH
+        saved_limit = self.cx.getlimit(category)
+        try:
+            new_limit = 10
+            prev_limit = self.cx.setlimit(category, new_limit)
+            self.assertEqual(saved_limit, prev_limit)
+            self.assertEqual(self.cx.getlimit(category), new_limit)
+            msg = "query string is too large"
+            self.assertRaisesRegex(sqlite.DataError, msg,
+                                   self.cx.execute, "select 1 as '16'")
+        finally:  # restore saved limit
+            self.cx.setlimit(category, saved_limit)
+
+    def test_connection_bad_limit_category(self):
+        msg = "'category' is out of bounds"
+        cat = 1111
+        self.assertRaisesRegex(sqlite.ProgrammingError, msg,
+                               self.cx.getlimit, cat)
+        self.assertRaisesRegex(sqlite.ProgrammingError, msg,
+                               self.cx.setlimit, cat, 0)
+
+    def test_connection_init_bad_isolation_level(self):
+        msg = (
+            "isolation_level string must be '', 'DEFERRED', 'IMMEDIATE', or "
+            "'EXCLUSIVE'"
+        )
+        levels = (
+            "BOGUS",
+            " ",
+            "DEFERRE",
+            "IMMEDIAT",
+            "EXCLUSIV",
+            "DEFERREDS",
+            "IMMEDIATES",
+            "EXCLUSIVES",
+        )
+        for level in levels:
+            with self.subTest(level=level):
+                with self.assertRaisesRegex(ValueError, msg):
+                    memory_database(isolation_level=level)
+                with memory_database() as cx:
+                    with self.assertRaisesRegex(ValueError, msg):
+                        cx.isolation_level = level
+                    # Check that the default level is not changed
+                    self.assertEqual(cx.isolation_level, "")
+
+    def test_connection_init_good_isolation_levels(self):
+        for level in ("", "DEFERRED", "IMMEDIATE", "EXCLUSIVE", None):
+            with self.subTest(level=level):
+                with memory_database(isolation_level=level) as cx:
+                    self.assertEqual(cx.isolation_level, level)
+                with memory_database() as cx:
+                    self.assertEqual(cx.isolation_level, "")
+                    cx.isolation_level = level
+                    self.assertEqual(cx.isolation_level, level)
+
+    def test_connection_reinit(self):
+        db = ":memory:"
+        cx = sqlite.connect(db)
+        cx.text_factory = bytes
+        cx.row_factory = sqlite.Row
+        cu = cx.cursor()
+        cu.execute("create table foo (bar)")
+        cu.executemany("insert into foo (bar) values (?)",
+                       ((str(v),) for v in range(4)))
+        cu.execute("select bar from foo")
+
+        rows = [r for r in cu.fetchmany(2)]
+        self.assertTrue(all(isinstance(r, sqlite.Row) for r in rows))
+        self.assertEqual([r[0] for r in rows], [b"0", b"1"])
+
+        cx.__init__(db)
+        cx.execute("create table foo (bar)")
+        cx.executemany("insert into foo (bar) values (?)",
+                       ((v,) for v in ("a", "b", "c", "d")))
+
+        # This uses the old database, old row factory, but new text factory
+        rows = [r for r in cu.fetchall()]
+        self.assertTrue(all(isinstance(r, sqlite.Row) for r in rows))
+        self.assertEqual([r[0] for r in rows], ["2", "3"])
+
+    def test_connection_bad_reinit(self):
+        cx = sqlite.connect(":memory:")
+        with cx:
+            cx.execute("create table t(t)")
+        with temp_dir() as db:
+            self.assertRaisesRegex(sqlite.OperationalError,
+                                   "unable to open database file",
+                                   cx.__init__, db)
+            self.assertRaisesRegex(sqlite.ProgrammingError,
+                                   "Base Connection.__init__ not called",
+                                   cx.executemany, "insert into t values(?)",
+                                   ((v,) for v in range(3)))
+
+
+class UninitialisedConnectionTests(unittest.TestCase):
+    def setUp(self):
+        self.cx = sqlite.Connection.__new__(sqlite.Connection)
+
+    def test_uninit_operations(self):
+        funcs = (
+            lambda: self.cx.isolation_level,
+            lambda: self.cx.total_changes,
+            lambda: self.cx.in_transaction,
+            lambda: self.cx.iterdump(),
+            lambda: self.cx.cursor(),
+            lambda: self.cx.close(),
+        )
+        for func in funcs:
+            with self.subTest(func=func):
+                self.assertRaisesRegex(sqlite.ProgrammingError,
+                                       "Base Connection.__init__ not called",
+                                       func)
+
+
+@unittest.skipUnless(hasattr(sqlite.Connection, "serialize"),
+                     "Needs SQLite serialize API")
+class SerializeTests(unittest.TestCase):
+    def test_serialize_deserialize(self):
+        with memory_database() as cx:
+            with cx:
+                cx.execute("create table t(t)")
+            data = cx.serialize()
+            self.assertEqual(len(data), 8192)
+
+            # Remove test table, verify that it was removed.
+            with cx:
+                cx.execute("drop table t")
+            regex = "no such table"
+            with self.assertRaisesRegex(sqlite.OperationalError, regex):
+                cx.execute("select t from t")
+
+            # Deserialize and verify that test table is restored.
+            cx.deserialize(data)
+            cx.execute("select t from t")
+
+    def test_deserialize_wrong_args(self):
+        dataset = (
+            (BufferError, memoryview(b"blob")[::2]),
+            (TypeError, []),
+            (TypeError, 1),
+            (TypeError, None),
+        )
+        for exc, arg in dataset:
+            with self.subTest(exc=exc, arg=arg):
+                with memory_database() as cx:
+                    self.assertRaises(exc, cx.deserialize, arg)
+
+    def test_deserialize_corrupt_database(self):
+        with memory_database() as cx:
+            regex = "file is not a database"
+            with self.assertRaisesRegex(sqlite.DatabaseError, regex):
+                cx.deserialize(b"\0\1\3")
+                # SQLite does not generate an error until you try to query the
+                # deserialized database.
+                cx.execute("create table fail(f)")
+
+
+class OpenTests(unittest.TestCase):
+    _sql = "create table test(id integer)"
+
+    def test_open_with_path_like_object(self):
+        """ Checks that we can successfully connect to a database using an object that
+            is PathLike, i.e. has __fspath__(). """
+        path = FakePath(TESTFN)
+        self.addCleanup(unlink, path)
+        self.assertFalse(os.path.exists(path))
+        with contextlib.closing(sqlite.connect(path)) as cx:
+            self.assertTrue(os.path.exists(path))
+            cx.execute(self._sql)
+
+    @unittest.skipIf(sys.platform == "win32", "skipped on Windows")
+    @unittest.skipIf(sys.platform == "darwin", "skipped on macOS")
+    @unittest.skipUnless(TESTFN_UNDECODABLE, "only works if there are undecodable paths")
+    def test_open_with_undecodable_path(self):
+        path = TESTFN_UNDECODABLE
+        self.addCleanup(unlink, path)
+        self.assertFalse(os.path.exists(path))
+        with contextlib.closing(sqlite.connect(path)) as cx:
+            self.assertTrue(os.path.exists(path))
+            cx.execute(self._sql)
+
+    def test_open_uri(self):
+        path = TESTFN
+        self.addCleanup(unlink, path)
+        uri = "file:" + urllib.parse.quote(os.fsencode(path))
+        self.assertFalse(os.path.exists(path))
+        with contextlib.closing(sqlite.connect(uri, uri=True)) as cx:
+            self.assertTrue(os.path.exists(path))
+            cx.execute(self._sql)
+
+    def test_open_unquoted_uri(self):
+        path = TESTFN
+        self.addCleanup(unlink, path)
+        uri = "file:" + path
+        self.assertFalse(os.path.exists(path))
+        with contextlib.closing(sqlite.connect(uri, uri=True)) as cx:
+            self.assertTrue(os.path.exists(path))
+            cx.execute(self._sql)
+
+    def test_open_uri_readonly(self):
+        path = TESTFN
+        self.addCleanup(unlink, path)
+        uri = "file:" + urllib.parse.quote(os.fsencode(path)) + "?mode=ro"
+        self.assertFalse(os.path.exists(path))
+        # Cannot create new DB
+        with self.assertRaises(sqlite.OperationalError):
+            sqlite.connect(uri, uri=True)
+        self.assertFalse(os.path.exists(path))
+        sqlite.connect(path).close()
+        self.assertTrue(os.path.exists(path))
+        # Cannot modify new DB
+        with contextlib.closing(sqlite.connect(uri, uri=True)) as cx:
+            with self.assertRaises(sqlite.OperationalError):
+                cx.execute(self._sql)
+
+    @unittest.skipIf(sys.platform == "win32", "skipped on Windows")
+    @unittest.skipIf(sys.platform == "darwin", "skipped on macOS")
+    @unittest.skipUnless(TESTFN_UNDECODABLE, "only works if there are undecodable paths")
+    def test_open_undecodable_uri(self):
+        path = TESTFN_UNDECODABLE
+        self.addCleanup(unlink, path)
+        uri = "file:" + urllib.parse.quote(path)
+        self.assertFalse(os.path.exists(path))
+        with contextlib.closing(sqlite.connect(uri, uri=True)) as cx:
+            self.assertTrue(os.path.exists(path))
+            cx.execute(self._sql)
+
+    def test_factory_database_arg(self):
+        def factory(database, *args, **kwargs):
+            nonlocal database_arg
+            database_arg = database
+            return sqlite.Connection(":memory:", *args, **kwargs)
+
+        for database in (TESTFN, os.fsencode(TESTFN),
+                         FakePath(TESTFN), FakePath(os.fsencode(TESTFN))):
+            database_arg = None
+            sqlite.connect(database, factory=factory).close()
+            self.assertEqual(database_arg, database)
+
+    def test_database_keyword(self):
+        with contextlib.closing(sqlite.connect(database=":memory:")) as cx:
+            self.assertEqual(type(cx), sqlite.Connection)
+
+
+class CursorTests(unittest.TestCase):
+    def setUp(self):
+        self.cx = sqlite.connect(":memory:")
+        self.cu = self.cx.cursor()
+        self.cu.execute(
+            "create table test(id integer primary key, name text, "
+            "income number, unique_test text unique)"
+        )
+        self.cu.execute("insert into test(name) values (?)", ("foo",))
+
+    def tearDown(self):
+        self.cu.close()
+        self.cx.close()
+
+    def test_execute_no_args(self):
+        self.cu.execute("delete from test")
+
+    def test_execute_illegal_sql(self):
+        with self.assertRaises(sqlite.OperationalError):
+            self.cu.execute("select asdf")
+
+    def test_execute_multiple_statements(self):
+        msg = "You can only execute one statement at a time"
+        dataset = (
+            "select 1; select 2",
+            "select 1; // c++ comments are not allowed",
+            "select 1; *not a comment",
+            "select 1; -*not a comment",
+            "select 1; /* */ a",
+            "select 1; /**/a",
+            "select 1; -",
+            "select 1; /",
+            "select 1; -\n- select 2",
+            """select 1;
+               -- comment
+               select 2
+            """,
+        )
+        for query in dataset:
+            with self.subTest(query=query):
+                with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                    self.cu.execute(query)
+
+    def test_execute_with_appended_comments(self):
+        dataset = (
+            "select 1; -- foo bar",
+            "select 1; --",
+            "select 1; /*",  # Unclosed comments ending in \0 are skipped.
+            """
+            select 5+4;
+
+            /*
+            foo
+            */
+            """,
+        )
+        for query in dataset:
+            with self.subTest(query=query):
+                self.cu.execute(query)
+
+    def test_execute_wrong_sql_arg(self):
+        with self.assertRaises(TypeError):
+            self.cu.execute(42)
+
+    def test_execute_arg_int(self):
+        self.cu.execute("insert into test(id) values (?)", (42,))
+
+    def test_execute_arg_float(self):
+        self.cu.execute("insert into test(income) values (?)", (2500.32,))
+
+    def test_execute_arg_string(self):
+        self.cu.execute("insert into test(name) values (?)", ("Hugo",))
+
+    def test_execute_arg_string_with_zero_byte(self):
+        self.cu.execute("insert into test(name) values (?)", ("Hu\x00go",))
+
+        self.cu.execute("select name from test where id=?", (self.cu.lastrowid,))
+        row = self.cu.fetchone()
+        self.assertEqual(row[0], "Hu\x00go")
+
+    def test_execute_non_iterable(self):
+        with self.assertRaises(sqlite.ProgrammingError) as cm:
+            self.cu.execute("insert into test(id) values (?)", 42)
+        self.assertEqual(str(cm.exception), 'parameters are of unsupported type')
+
+    def test_execute_wrong_no_of_args1(self):
+        # too many parameters
+        with self.assertRaises(sqlite.ProgrammingError):
+            self.cu.execute("insert into test(id) values (?)", (17, "Egon"))
+
+    def test_execute_wrong_no_of_args2(self):
+        # too little parameters
+        with self.assertRaises(sqlite.ProgrammingError):
+            self.cu.execute("insert into test(id) values (?)")
+
+    def test_execute_wrong_no_of_args3(self):
+        # no parameters, parameters are needed
+        with self.assertRaises(sqlite.ProgrammingError):
+            self.cu.execute("insert into test(id) values (?)")
+
+    def test_execute_param_list(self):
+        self.cu.execute("insert into test(name) values ('foo')")
+        self.cu.execute("select name from test where name=?", ["foo"])
+        row = self.cu.fetchone()
+        self.assertEqual(row[0], "foo")
+
+    def test_execute_param_sequence(self):
+        class L:
+            def __len__(self):
+                return 1
+            def __getitem__(self, x):
+                assert x == 0
+                return "foo"
+
+        self.cu.execute("insert into test(name) values ('foo')")
+        self.cu.execute("select name from test where name=?", L())
+        row = self.cu.fetchone()
+        self.assertEqual(row[0], "foo")
+
+    def test_execute_param_sequence_bad_len(self):
+        # Issue41662: Error in __len__() was overridden with ProgrammingError.
+        class L:
+            def __len__(self):
+                1/0
+            def __getitem__(slf, x):
+                raise AssertionError
+
+        self.cu.execute("insert into test(name) values ('foo')")
+        with self.assertRaises(ZeroDivisionError):
+            self.cu.execute("select name from test where name=?", L())
+
+    def test_execute_too_many_params(self):
+        category = sqlite.SQLITE_LIMIT_VARIABLE_NUMBER
+        msg = "too many SQL variables"
+        with cx_limit(self.cx, category=category, limit=1):
+            self.cu.execute("select * from test where id=?", (1,))
+            with self.assertRaisesRegex(sqlite.OperationalError, msg):
+                self.cu.execute("select * from test where id!=? and id!=?",
+                                (1, 2))
+
+    def test_execute_dict_mapping(self):
+        self.cu.execute("insert into test(name) values ('foo')")
+        self.cu.execute("select name from test where name=:name", {"name": "foo"})
+        row = self.cu.fetchone()
+        self.assertEqual(row[0], "foo")
+
+    def test_execute_dict_mapping_mapping(self):
+        class D(dict):
+            def __missing__(self, key):
+                return "foo"
+
+        self.cu.execute("insert into test(name) values ('foo')")
+        self.cu.execute("select name from test where name=:name", D())
+        row = self.cu.fetchone()
+        self.assertEqual(row[0], "foo")
+
+    def test_execute_dict_mapping_too_little_args(self):
+        self.cu.execute("insert into test(name) values ('foo')")
+        with self.assertRaises(sqlite.ProgrammingError):
+            self.cu.execute("select name from test where name=:name and id=:id", {"name": "foo"})
+
+    def test_execute_dict_mapping_no_args(self):
+        self.cu.execute("insert into test(name) values ('foo')")
+        with self.assertRaises(sqlite.ProgrammingError):
+            self.cu.execute("select name from test where name=:name")
+
+    def test_execute_dict_mapping_unnamed(self):
+        self.cu.execute("insert into test(name) values ('foo')")
+        with self.assertRaises(sqlite.ProgrammingError):
+            self.cu.execute("select name from test where name=?", {"name": "foo"})
+
+    def test_close(self):
+        self.cu.close()
+
+    def test_rowcount_execute(self):
+        self.cu.execute("delete from test")
+        self.cu.execute("insert into test(name) values ('foo')")
+        self.cu.execute("insert into test(name) values ('foo')")
+        self.cu.execute("update test set name='bar'")
+        self.assertEqual(self.cu.rowcount, 2)
+
+    def test_rowcount_select(self):
+        """
+        pysqlite does not know the rowcount of SELECT statements, because we
+        don't fetch all rows after executing the select statement. The rowcount
+        has thus to be -1.
+        """
+        self.cu.execute("select 5 union select 6")
+        self.assertEqual(self.cu.rowcount, -1)
+
+    def test_rowcount_executemany(self):
+        self.cu.execute("delete from test")
+        self.cu.executemany("insert into test(name) values (?)", [(1,), (2,), (3,)])
+        self.assertEqual(self.cu.rowcount, 3)
+
+    @unittest.skipIf(sqlite.sqlite_version_info < (3, 35, 0),
+                     "Requires SQLite 3.35.0 or newer")
+    def test_rowcount_update_returning(self):
+        # gh-93421: rowcount is updated correctly for UPDATE...RETURNING queries
+        self.cu.execute("update test set name='bar' where name='foo' returning 1")
+        self.assertEqual(self.cu.fetchone()[0], 1)
+        self.assertEqual(self.cu.rowcount, 1)
+
+    def test_rowcount_prefixed_with_comment(self):
+        # gh-79579: rowcount is updated even if query is prefixed with comments
+        self.cu.execute("""
+            -- foo
+            insert into test(name) values ('foo'), ('foo')
+        """)
+        self.assertEqual(self.cu.rowcount, 2)
+        self.cu.execute("""
+            /* -- messy *r /* /* ** *- *--
+            */
+            /* one more */ insert into test(name) values ('messy')
+        """)
+        self.assertEqual(self.cu.rowcount, 1)
+        self.cu.execute("/* bar */ update test set name='bar' where name='foo'")
+        self.assertEqual(self.cu.rowcount, 3)
+
+    def test_rowcount_vaccuum(self):
+        data = ((1,), (2,), (3,))
+        self.cu.executemany("insert into test(income) values(?)", data)
+        self.assertEqual(self.cu.rowcount, 3)
+        self.cx.commit()
+        self.cu.execute("vacuum")
+        self.assertEqual(self.cu.rowcount, -1)
+
+    def test_total_changes(self):
+        self.cu.execute("insert into test(name) values ('foo')")
+        self.cu.execute("insert into test(name) values ('foo')")
+        self.assertLess(2, self.cx.total_changes, msg='total changes reported wrong value')
+
+    # Checks for executemany:
+    # Sequences are required by the DB-API, iterators
+    # enhancements in pysqlite.
+
+    def test_execute_many_sequence(self):
+        self.cu.executemany("insert into test(income) values (?)", [(x,) for x in range(100, 110)])
+
+    def test_execute_many_iterator(self):
+        class MyIter:
+            def __init__(self):
+                self.value = 5
+
+            def __iter__(self):
+                return self
+
+            def __next__(self):
+                if self.value == 10:
+                    raise StopIteration
+                else:
+                    self.value += 1
+                    return (self.value,)
+
+        self.cu.executemany("insert into test(income) values (?)", MyIter())
+
+    def test_execute_many_generator(self):
+        def mygen():
+            for i in range(5):
+                yield (i,)
+
+        self.cu.executemany("insert into test(income) values (?)", mygen())
+
+    def test_execute_many_wrong_sql_arg(self):
+        with self.assertRaises(TypeError):
+            self.cu.executemany(42, [(3,)])
+
+    def test_execute_many_select(self):
+        with self.assertRaises(sqlite.ProgrammingError):
+            self.cu.executemany("select ?", [(3,)])
+
+    def test_execute_many_not_iterable(self):
+        with self.assertRaises(TypeError):
+            self.cu.executemany("insert into test(income) values (?)", 42)
+
+    def test_fetch_iter(self):
+        # Optional DB-API extension.
+        self.cu.execute("delete from test")
+        self.cu.execute("insert into test(id) values (?)", (5,))
+        self.cu.execute("insert into test(id) values (?)", (6,))
+        self.cu.execute("select id from test order by id")
+        lst = []
+        for row in self.cu:
+            lst.append(row[0])
+        self.assertEqual(lst[0], 5)
+        self.assertEqual(lst[1], 6)
+
+    def test_fetchone(self):
+        self.cu.execute("select name from test")
+        row = self.cu.fetchone()
+        self.assertEqual(row[0], "foo")
+        row = self.cu.fetchone()
+        self.assertEqual(row, None)
+
+    def test_fetchone_no_statement(self):
+        cur = self.cx.cursor()
+        row = cur.fetchone()
+        self.assertEqual(row, None)
+
+    def test_array_size(self):
+        # must default to 1
+        self.assertEqual(self.cu.arraysize, 1)
+
+        # now set to 2
+        self.cu.arraysize = 2
+
+        # now make the query return 3 rows
+        self.cu.execute("delete from test")
+        self.cu.execute("insert into test(name) values ('A')")
+        self.cu.execute("insert into test(name) values ('B')")
+        self.cu.execute("insert into test(name) values ('C')")
+        self.cu.execute("select name from test")
+        res = self.cu.fetchmany()
+
+        self.assertEqual(len(res), 2)
+
+    def test_fetchmany(self):
+        self.cu.execute("select name from test")
+        res = self.cu.fetchmany(100)
+        self.assertEqual(len(res), 1)
+        res = self.cu.fetchmany(100)
+        self.assertEqual(res, [])
+
+    def test_fetchmany_kw_arg(self):
+        """Checks if fetchmany works with keyword arguments"""
+        self.cu.execute("select name from test")
+        res = self.cu.fetchmany(size=100)
+        self.assertEqual(len(res), 1)
+
+    def test_fetchall(self):
+        self.cu.execute("select name from test")
+        res = self.cu.fetchall()
+        self.assertEqual(len(res), 1)
+        res = self.cu.fetchall()
+        self.assertEqual(res, [])
+
+    def test_setinputsizes(self):
+        self.cu.setinputsizes([3, 4, 5])
+
+    def test_setoutputsize(self):
+        self.cu.setoutputsize(5, 0)
+
+    def test_setoutputsize_no_column(self):
+        self.cu.setoutputsize(42)
+
+    def test_cursor_connection(self):
+        # Optional DB-API extension.
+        self.assertEqual(self.cu.connection, self.cx)
+
+    def test_wrong_cursor_callable(self):
+        with self.assertRaises(TypeError):
+            def f(): pass
+            cur = self.cx.cursor(f)
+
+    def test_cursor_wrong_class(self):
+        class Foo: pass
+        foo = Foo()
+        with self.assertRaises(TypeError):
+            cur = sqlite.Cursor(foo)
+
+    def test_last_row_id_on_replace(self):
+        """
+        INSERT OR REPLACE and REPLACE INTO should produce the same behavior.
+        """
+        sql = '{} INTO test(id, unique_test) VALUES (?, ?)'
+        for statement in ('INSERT OR REPLACE', 'REPLACE'):
+            with self.subTest(statement=statement):
+                self.cu.execute(sql.format(statement), (1, 'foo'))
+                self.assertEqual(self.cu.lastrowid, 1)
+
+    def test_last_row_id_on_ignore(self):
+        self.cu.execute(
+            "insert or ignore into test(unique_test) values (?)",
+            ('test',))
+        self.assertEqual(self.cu.lastrowid, 2)
+        self.cu.execute(
+            "insert or ignore into test(unique_test) values (?)",
+            ('test',))
+        self.assertEqual(self.cu.lastrowid, 2)
+
+    def test_last_row_id_insert_o_r(self):
+        results = []
+        for statement in ('FAIL', 'ABORT', 'ROLLBACK'):
+            sql = 'INSERT OR {} INTO test(unique_test) VALUES (?)'
+            with self.subTest(statement='INSERT OR {}'.format(statement)):
+                self.cu.execute(sql.format(statement), (statement,))
+                results.append((statement, self.cu.lastrowid))
+                with self.assertRaises(sqlite.IntegrityError):
+                    self.cu.execute(sql.format(statement), (statement,))
+                results.append((statement, self.cu.lastrowid))
+        expected = [
+            ('FAIL', 2), ('FAIL', 2),
+            ('ABORT', 3), ('ABORT', 3),
+            ('ROLLBACK', 4), ('ROLLBACK', 4),
+        ]
+        self.assertEqual(results, expected)
+
+    def test_column_count(self):
+        # Check that column count is updated correctly for cached statements
+        select = "select * from test"
+        res = self.cu.execute(select)
+        old_count = len(res.description)
+        # Add a new column and execute the cached select query again
+        self.cu.execute("alter table test add newcol")
+        res = self.cu.execute(select)
+        new_count = len(res.description)
+        self.assertEqual(new_count - old_count, 1)
+
+    def test_same_query_in_multiple_cursors(self):
+        cursors = [self.cx.execute("select 1") for _ in range(3)]
+        for cu in cursors:
+            self.assertEqual(cu.fetchall(), [(1,)])
+
+
+class BlobTests(unittest.TestCase):
+    def setUp(self):
+        self.cx = sqlite.connect(":memory:")
+        self.cx.execute("create table test(b blob)")
+        self.data = b"this blob data string is exactly fifty bytes long!"
+        self.cx.execute("insert into test(b) values (?)", (self.data,))
+        self.blob = self.cx.blobopen("test", "b", 1)
+
+    def tearDown(self):
+        self.blob.close()
+        self.cx.close()
+
+    def test_blob_is_a_blob(self):
+        self.assertIsInstance(self.blob, sqlite.Blob)
+
+    def test_blob_seek_and_tell(self):
+        self.blob.seek(10)
+        self.assertEqual(self.blob.tell(), 10)
+
+        self.blob.seek(10, SEEK_SET)
+        self.assertEqual(self.blob.tell(), 10)
+
+        self.blob.seek(10, SEEK_CUR)
+        self.assertEqual(self.blob.tell(), 20)
+
+        self.blob.seek(-10, SEEK_END)
+        self.assertEqual(self.blob.tell(), 40)
+
+    def test_blob_seek_error(self):
+        msg_oor = "offset out of blob range"
+        msg_orig = "'origin' should be os.SEEK_SET, os.SEEK_CUR, or os.SEEK_END"
+        msg_of = "seek offset results in overflow"
+
+        dataset = (
+            (ValueError, msg_oor, lambda: self.blob.seek(1000)),
+            (ValueError, msg_oor, lambda: self.blob.seek(-10)),
+            (ValueError, msg_orig, lambda: self.blob.seek(10, -1)),
+            (ValueError, msg_orig, lambda: self.blob.seek(10, 3)),
+        )
+        for exc, msg, fn in dataset:
+            with self.subTest(exc=exc, msg=msg, fn=fn):
+                self.assertRaisesRegex(exc, msg, fn)
+
+        # Force overflow errors
+        self.blob.seek(1, SEEK_SET)
+        with self.assertRaisesRegex(OverflowError, msg_of):
+            self.blob.seek(INT_MAX, SEEK_CUR)
+        with self.assertRaisesRegex(OverflowError, msg_of):
+            self.blob.seek(INT_MAX, SEEK_END)
+
+    def test_blob_read(self):
+        buf = self.blob.read()
+        self.assertEqual(buf, self.data)
+
+    def test_blob_read_oversized(self):
+        buf = self.blob.read(len(self.data) * 2)
+        self.assertEqual(buf, self.data)
+
+    def test_blob_read_advance_offset(self):
+        n = 10
+        buf = self.blob.read(n)
+        self.assertEqual(buf, self.data[:n])
+        self.assertEqual(self.blob.tell(), n)
+
+    def test_blob_read_at_offset(self):
+        self.blob.seek(10)
+        self.assertEqual(self.blob.read(10), self.data[10:20])
+
+    def test_blob_read_error_row_changed(self):
+        self.cx.execute("update test set b='aaaa' where rowid=1")
+        with self.assertRaises(sqlite.OperationalError):
+            self.blob.read()
+
+    def test_blob_write(self):
+        new_data = b"new data".ljust(50)
+        self.blob.write(new_data)
+        row = self.cx.execute("select b from test").fetchone()
+        self.assertEqual(row[0], new_data)
+
+    def test_blob_write_at_offset(self):
+        new_data = b"c" * 25
+        self.blob.seek(25)
+        self.blob.write(new_data)
+        row = self.cx.execute("select b from test").fetchone()
+        self.assertEqual(row[0], self.data[:25] + new_data)
+
+    def test_blob_write_advance_offset(self):
+        self.blob.write(b"d"*10)
+        self.assertEqual(self.blob.tell(), 10)
+
+    def test_blob_write_error_length(self):
+        with self.assertRaisesRegex(ValueError, "data longer than blob"):
+            self.blob.write(b"a" * 1000)
+
+        self.blob.seek(0, SEEK_SET)
+        n = len(self.blob)
+        self.blob.write(b"a" * (n-1))
+        self.blob.write(b"a")
+        with self.assertRaisesRegex(ValueError, "data longer than blob"):
+            self.blob.write(b"a")
+
+    def test_blob_write_error_row_changed(self):
+        self.cx.execute("update test set b='aaaa' where rowid=1")
+        with self.assertRaises(sqlite.OperationalError):
+            self.blob.write(b"aaa")
+
+    def test_blob_write_error_readonly(self):
+        ro_blob = self.cx.blobopen("test", "b", 1, readonly=True)
+        with self.assertRaisesRegex(sqlite.OperationalError, "readonly"):
+            ro_blob.write(b"aaa")
+        ro_blob.close()
+
+    def test_blob_open_error(self):
+        dataset = (
+            (("test", "b", 1), {"name": "notexisting"}),
+            (("notexisting", "b", 1), {}),
+            (("test", "notexisting", 1), {}),
+            (("test", "b", 2), {}),
+        )
+        regex = "no such"
+        for args, kwds in dataset:
+            with self.subTest(args=args, kwds=kwds):
+                with self.assertRaisesRegex(sqlite.OperationalError, regex):
+                    self.cx.blobopen(*args, **kwds)
+
+    def test_blob_length(self):
+        self.assertEqual(len(self.blob), 50)
+
+    def test_blob_get_item(self):
+        self.assertEqual(self.blob[5], ord("b"))
+        self.assertEqual(self.blob[6], ord("l"))
+        self.assertEqual(self.blob[7], ord("o"))
+        self.assertEqual(self.blob[8], ord("b"))
+        self.assertEqual(self.blob[-1], ord("!"))
+
+    def test_blob_set_item(self):
+        self.blob[0] = ord("b")
+        expected = b"b" + self.data[1:]
+        actual = self.cx.execute("select b from test").fetchone()[0]
+        self.assertEqual(actual, expected)
+
+    def test_blob_set_item_with_offset(self):
+        self.blob.seek(0, SEEK_END)
+        self.assertEqual(self.blob.read(), b"")  # verify that we're at EOB
+        self.blob[0] = ord("T")
+        self.blob[-1] = ord(".")
+        self.blob.seek(0, SEEK_SET)
+        expected = b"This blob data string is exactly fifty bytes long."
+        self.assertEqual(self.blob.read(), expected)
+
+    def test_blob_set_slice_buffer_object(self):
+        from array import array
+        self.blob[0:5] = memoryview(b"12345")
+        self.assertEqual(self.blob[0:5], b"12345")
+
+        self.blob[0:5] = bytearray(b"23456")
+        self.assertEqual(self.blob[0:5], b"23456")
+
+        self.blob[0:5] = array("b", [1, 2, 3, 4, 5])
+        self.assertEqual(self.blob[0:5], b"\x01\x02\x03\x04\x05")
+
+    def test_blob_set_item_negative_index(self):
+        self.blob[-1] = 255
+        self.assertEqual(self.blob[-1], 255)
+
+    def test_blob_get_slice(self):
+        self.assertEqual(self.blob[5:14], b"blob data")
+
+    def test_blob_get_empty_slice(self):
+        self.assertEqual(self.blob[5:5], b"")
+
+    def test_blob_get_slice_negative_index(self):
+        self.assertEqual(self.blob[5:-5], self.data[5:-5])
+
+    def test_blob_get_slice_with_skip(self):
+        self.assertEqual(self.blob[0:10:2], b"ti lb")
+
+    def test_blob_set_slice(self):
+        self.blob[0:5] = b"12345"
+        expected = b"12345" + self.data[5:]
+        actual = self.cx.execute("select b from test").fetchone()[0]
+        self.assertEqual(actual, expected)
+
+    def test_blob_set_empty_slice(self):
+        self.blob[0:0] = b""
+        self.assertEqual(self.blob[:], self.data)
+
+    def test_blob_set_slice_with_skip(self):
+        self.blob[0:10:2] = b"12345"
+        actual = self.cx.execute("select b from test").fetchone()[0]
+        expected = b"1h2s3b4o5 " + self.data[10:]
+        self.assertEqual(actual, expected)
+
+    def test_blob_mapping_invalid_index_type(self):
+        msg = "indices must be integers"
+        with self.assertRaisesRegex(TypeError, msg):
+            self.blob[5:5.5]
+        with self.assertRaisesRegex(TypeError, msg):
+            self.blob[1.5]
+        with self.assertRaisesRegex(TypeError, msg):
+            self.blob["a"] = b"b"
+
+    def test_blob_get_item_error(self):
+        dataset = [len(self.blob), 105, -105]
+        for idx in dataset:
+            with self.subTest(idx=idx):
+                with self.assertRaisesRegex(IndexError, "index out of range"):
+                    self.blob[idx]
+        with self.assertRaisesRegex(IndexError, "cannot fit 'int'"):
+            self.blob[ULLONG_MAX]
+
+        # Provoke read error
+        self.cx.execute("update test set b='aaaa' where rowid=1")
+        with self.assertRaises(sqlite.OperationalError):
+            self.blob[0]
+
+    def test_blob_set_item_error(self):
+        with self.assertRaisesRegex(TypeError, "cannot be interpreted"):
+            self.blob[0] = b"multiple"
+        with self.assertRaisesRegex(TypeError, "cannot be interpreted"):
+            self.blob[0] = b"1"
+        with self.assertRaisesRegex(TypeError, "cannot be interpreted"):
+            self.blob[0] = bytearray(b"1")
+        with self.assertRaisesRegex(TypeError, "doesn't support.*deletion"):
+            del self.blob[0]
+        with self.assertRaisesRegex(IndexError, "Blob index out of range"):
+            self.blob[1000] = 0
+        with self.assertRaisesRegex(ValueError, "must be in range"):
+            self.blob[0] = -1
+        with self.assertRaisesRegex(ValueError, "must be in range"):
+            self.blob[0] = 256
+        # Overflow errors are overridden with ValueError
+        with self.assertRaisesRegex(ValueError, "must be in range"):
+            self.blob[0] = 2**65
+
+    def test_blob_set_slice_error(self):
+        with self.assertRaisesRegex(IndexError, "wrong size"):
+            self.blob[5:10] = b"a"
+        with self.assertRaisesRegex(IndexError, "wrong size"):
+            self.blob[5:10] = b"a" * 1000
+        with self.assertRaisesRegex(TypeError, "doesn't support.*deletion"):
+            del self.blob[5:10]
+        with self.assertRaisesRegex(ValueError, "step cannot be zero"):
+            self.blob[5:10:0] = b"12345"
+        with self.assertRaises(BufferError):
+            self.blob[5:10] = memoryview(b"abcde")[::2]
+
+    def test_blob_sequence_not_supported(self):
+        with self.assertRaisesRegex(TypeError, "unsupported operand"):
+            self.blob + self.blob
+        with self.assertRaisesRegex(TypeError, "unsupported operand"):
+            self.blob * 5
+        with self.assertRaisesRegex(TypeError, "is not iterable"):
+            b"a" in self.blob
+
+    def test_blob_context_manager(self):
+        data = b"a" * 50
+        with self.cx.blobopen("test", "b", 1) as blob:
+            blob.write(data)
+        actual = self.cx.execute("select b from test").fetchone()[0]
+        self.assertEqual(actual, data)
+
+        # Check that __exit__ closed the blob
+        with self.assertRaisesRegex(sqlite.ProgrammingError, "closed blob"):
+            blob.read()
+
+    def test_blob_context_manager_reraise_exceptions(self):
+        class DummyException(Exception):
+            pass
+        with self.assertRaisesRegex(DummyException, "reraised"):
+            with self.cx.blobopen("test", "b", 1) as blob:
+                raise DummyException("reraised")
+
+
+    def test_blob_closed(self):
+        with memory_database() as cx:
+            cx.execute("create table test(b blob)")
+            cx.execute("insert into test values (zeroblob(100))")
+            blob = cx.blobopen("test", "b", 1)
+            blob.close()
+
+            msg = "Cannot operate on a closed blob"
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                blob.read()
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                blob.write(b"")
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                blob.seek(0)
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                blob.tell()
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                blob.__enter__()
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                blob.__exit__(None, None, None)
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                len(blob)
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                blob[0]
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                blob[0:1]
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                blob[0] = b""
+
+    def test_blob_closed_db_read(self):
+        with memory_database() as cx:
+            cx.execute("create table test(b blob)")
+            cx.execute("insert into test(b) values (zeroblob(100))")
+            blob = cx.blobopen("test", "b", 1)
+            cx.close()
+            self.assertRaisesRegex(sqlite.ProgrammingError,
+                                   "Cannot operate on a closed database",
+                                   blob.read)
+
+
+class ThreadTests(unittest.TestCase):
+    def setUp(self):
+        self.con = sqlite.connect(":memory:")
+        self.cur = self.con.cursor()
+        self.cur.execute("create table test(name text, b blob)")
+        self.cur.execute("insert into test values('blob', zeroblob(1))")
+
+    def tearDown(self):
+        self.cur.close()
+        self.con.close()
+
+    @threading_helper.reap_threads
+    def _run_test(self, fn, *args, **kwds):
+        def run(err):
+            try:
+                fn(*args, **kwds)
+                err.append("did not raise ProgrammingError")
+            except sqlite.ProgrammingError:
+                pass
+            except:
+                err.append("raised wrong exception")
+
+        err = []
+        t = threading.Thread(target=run, kwargs={"err": err})
+        t.start()
+        t.join()
+        if err:
+            self.fail("\n".join(err))
+
+    def test_check_connection_thread(self):
+        fns = [
+            lambda: self.con.cursor(),
+            lambda: self.con.commit(),
+            lambda: self.con.rollback(),
+            lambda: self.con.close(),
+            lambda: self.con.set_trace_callback(None),
+            lambda: self.con.set_authorizer(None),
+            lambda: self.con.create_collation("foo", None),
+            lambda: self.con.setlimit(sqlite.SQLITE_LIMIT_LENGTH, -1),
+            lambda: self.con.getlimit(sqlite.SQLITE_LIMIT_LENGTH),
+            lambda: self.con.blobopen("test", "b", 1),
+        ]
+        if hasattr(sqlite.Connection, "serialize"):
+            fns.append(lambda: self.con.serialize())
+            fns.append(lambda: self.con.deserialize(b""))
+        if sqlite.sqlite_version_info >= (3, 25, 0):
+            fns.append(lambda: self.con.create_window_function("foo", 0, None))
+
+        for fn in fns:
+            with self.subTest(fn=fn):
+                self._run_test(fn)
+
+    def test_check_cursor_thread(self):
+        fns = [
+            lambda: self.cur.execute("insert into test(name) values('a')"),
+            lambda: self.cur.close(),
+            lambda: self.cur.execute("select name from test"),
+            lambda: self.cur.fetchone(),
+        ]
+        for fn in fns:
+            with self.subTest(fn=fn):
+                self._run_test(fn)
+
+
+    @threading_helper.reap_threads
+    def test_dont_check_same_thread(self):
+        def run(con, err):
+            try:
+                con.execute("select 1")
+            except sqlite.Error:
+                err.append("multi-threading not allowed")
+
+        con = sqlite.connect(":memory:", check_same_thread=False)
+        err = []
+        t = threading.Thread(target=run, kwargs={"con": con, "err": err})
+        t.start()
+        t.join()
+        self.assertEqual(len(err), 0, "\n".join(err))
+
+
+class ConstructorTests(unittest.TestCase):
+    def test_date(self):
+        d = sqlite.Date(2004, 10, 28)
+
+    def test_time(self):
+        t = sqlite.Time(12, 39, 35)
+
+    def test_timestamp(self):
+        ts = sqlite.Timestamp(2004, 10, 28, 12, 39, 35)
+
+    def test_date_from_ticks(self):
+        d = sqlite.DateFromTicks(42)
+
+    def test_time_from_ticks(self):
+        t = sqlite.TimeFromTicks(42)
+
+    def test_timestamp_from_ticks(self):
+        ts = sqlite.TimestampFromTicks(42)
+
+    def test_binary(self):
+        b = sqlite.Binary(b"\0'")
+
+class ExtensionTests(unittest.TestCase):
+    def test_script_string_sql(self):
+        con = sqlite.connect(":memory:")
+        cur = con.cursor()
+        cur.executescript("""
+            -- bla bla
+            /* a stupid comment */
+            create table a(i);
+            insert into a(i) values (5);
+            """)
+        cur.execute("select i from a")
+        res = cur.fetchone()[0]
+        self.assertEqual(res, 5)
+
+    def test_script_syntax_error(self):
+        con = sqlite.connect(":memory:")
+        cur = con.cursor()
+        with self.assertRaises(sqlite.OperationalError):
+            cur.executescript("create table test(x); asdf; create table test2(x)")
+
+    def test_script_error_normal(self):
+        con = sqlite.connect(":memory:")
+        cur = con.cursor()
+        with self.assertRaises(sqlite.OperationalError):
+            cur.executescript("create table test(sadfsadfdsa); select foo from hurz;")
+
+    def test_cursor_executescript_as_bytes(self):
+        con = sqlite.connect(":memory:")
+        cur = con.cursor()
+        with self.assertRaises(TypeError):
+            cur.executescript(b"create table test(foo); insert into test(foo) values (5);")
+
+    def test_cursor_executescript_with_null_characters(self):
+        con = sqlite.connect(":memory:")
+        cur = con.cursor()
+        with self.assertRaises(ValueError):
+            cur.executescript("""
+                create table a(i);\0
+                insert into a(i) values (5);
+                """)
+
+    def test_cursor_executescript_with_surrogates(self):
+        con = sqlite.connect(":memory:")
+        cur = con.cursor()
+        with self.assertRaises(UnicodeEncodeError):
+            cur.executescript("""
+                create table a(s);
+                insert into a(s) values ('\ud8ff');
+                """)
+
+    def test_cursor_executescript_too_large_script(self):
+        msg = "query string is too large"
+        with memory_database() as cx, cx_limit(cx) as lim:
+            cx.executescript("select 'almost too large'".ljust(lim))
+            with self.assertRaisesRegex(sqlite.DataError, msg):
+                cx.executescript("select 'too large'".ljust(lim+1))
+
+    def test_cursor_executescript_tx_control(self):
+        con = sqlite.connect(":memory:")
+        con.execute("begin")
+        self.assertTrue(con.in_transaction)
+        con.executescript("select 1")
+        self.assertFalse(con.in_transaction)
+
+    def test_connection_execute(self):
+        con = sqlite.connect(":memory:")
+        result = con.execute("select 5").fetchone()[0]
+        self.assertEqual(result, 5, "Basic test of Connection.execute")
+
+    def test_connection_executemany(self):
+        con = sqlite.connect(":memory:")
+        con.execute("create table test(foo)")
+        con.executemany("insert into test(foo) values (?)", [(3,), (4,)])
+        result = con.execute("select foo from test order by foo").fetchall()
+        self.assertEqual(result[0][0], 3, "Basic test of Connection.executemany")
+        self.assertEqual(result[1][0], 4, "Basic test of Connection.executemany")
+
+    def test_connection_executescript(self):
+        con = sqlite.connect(":memory:")
+        con.executescript("create table test(foo); insert into test(foo) values (5);")
+        result = con.execute("select foo from test").fetchone()[0]
+        self.assertEqual(result, 5, "Basic test of Connection.executescript")
+
+class ClosedConTests(unittest.TestCase):
+    def test_closed_con_cursor(self):
+        con = sqlite.connect(":memory:")
+        con.close()
+        with self.assertRaises(sqlite.ProgrammingError):
+            cur = con.cursor()
+
+    def test_closed_con_commit(self):
+        con = sqlite.connect(":memory:")
+        con.close()
+        with self.assertRaises(sqlite.ProgrammingError):
+            con.commit()
+
+    def test_closed_con_rollback(self):
+        con = sqlite.connect(":memory:")
+        con.close()
+        with self.assertRaises(sqlite.ProgrammingError):
+            con.rollback()
+
+    def test_closed_cur_execute(self):
+        con = sqlite.connect(":memory:")
+        cur = con.cursor()
+        con.close()
+        with self.assertRaises(sqlite.ProgrammingError):
+            cur.execute("select 4")
+
+    def test_closed_create_function(self):
+        con = sqlite.connect(":memory:")
+        con.close()
+        def f(x): return 17
+        with self.assertRaises(sqlite.ProgrammingError):
+            con.create_function("foo", 1, f)
+
+    def test_closed_create_aggregate(self):
+        con = sqlite.connect(":memory:")
+        con.close()
+        class Agg:
+            def __init__(self):
+                pass
+            def step(self, x):
+                pass
+            def finalize(self):
+                return 17
+        with self.assertRaises(sqlite.ProgrammingError):
+            con.create_aggregate("foo", 1, Agg)
+
+    def test_closed_set_authorizer(self):
+        con = sqlite.connect(":memory:")
+        con.close()
+        def authorizer(*args):
+            return sqlite.DENY
+        with self.assertRaises(sqlite.ProgrammingError):
+            con.set_authorizer(authorizer)
+
+    def test_closed_set_progress_callback(self):
+        con = sqlite.connect(":memory:")
+        con.close()
+        def progress(): pass
+        with self.assertRaises(sqlite.ProgrammingError):
+            con.set_progress_handler(progress, 100)
+
+    def test_closed_call(self):
+        con = sqlite.connect(":memory:")
+        con.close()
+        with self.assertRaises(sqlite.ProgrammingError):
+            con()
+
+class ClosedCurTests(unittest.TestCase):
+    def test_closed(self):
+        con = sqlite.connect(":memory:")
+        cur = con.cursor()
+        cur.close()
+
+        for method_name in ("execute", "executemany", "executescript", "fetchall", "fetchmany", "fetchone"):
+            if method_name in ("execute", "executescript"):
+                params = ("select 4 union select 5",)
+            elif method_name == "executemany":
+                params = ("insert into foo(bar) values (?)", [(3,), (4,)])
+            else:
+                params = []
+
+            with self.assertRaises(sqlite.ProgrammingError):
+                method = getattr(cur, method_name)
+                method(*params)
+
+
+class SqliteOnConflictTests(unittest.TestCase):
+    """
+    Tests for SQLite's "insert on conflict" feature.
+
+    See https://www.sqlite.org/lang_conflict.html for details.
+    """
+
+    def setUp(self):
+        self.cx = sqlite.connect(":memory:")
+        self.cu = self.cx.cursor()
+        self.cu.execute("""
+          CREATE TABLE test(
+            id INTEGER PRIMARY KEY, name TEXT, unique_name TEXT UNIQUE
+          );
+        """)
+
+    def tearDown(self):
+        self.cu.close()
+        self.cx.close()
+
+    def test_on_conflict_rollback_with_explicit_transaction(self):
+        self.cx.isolation_level = None  # autocommit mode
+        self.cu = self.cx.cursor()
+        # Start an explicit transaction.
+        self.cu.execute("BEGIN")
+        self.cu.execute("INSERT INTO test(name) VALUES ('abort_test')")
+        self.cu.execute("INSERT OR ROLLBACK INTO test(unique_name) VALUES ('foo')")
+        with self.assertRaises(sqlite.IntegrityError):
+            self.cu.execute("INSERT OR ROLLBACK INTO test(unique_name) VALUES ('foo')")
+        # Use connection to commit.
+        self.cx.commit()
+        self.cu.execute("SELECT name, unique_name from test")
+        # Transaction should have rolled back and nothing should be in table.
+        self.assertEqual(self.cu.fetchall(), [])
+
+    def test_on_conflict_abort_raises_with_explicit_transactions(self):
+        # Abort cancels the current sql statement but doesn't change anything
+        # about the current transaction.
+        self.cx.isolation_level = None  # autocommit mode
+        self.cu = self.cx.cursor()
+        # Start an explicit transaction.
+        self.cu.execute("BEGIN")
+        self.cu.execute("INSERT INTO test(name) VALUES ('abort_test')")
+        self.cu.execute("INSERT OR ABORT INTO test(unique_name) VALUES ('foo')")
+        with self.assertRaises(sqlite.IntegrityError):
+            self.cu.execute("INSERT OR ABORT INTO test(unique_name) VALUES ('foo')")
+        self.cx.commit()
+        self.cu.execute("SELECT name, unique_name FROM test")
+        # Expect the first two inserts to work, third to do nothing.
+        self.assertEqual(self.cu.fetchall(), [('abort_test', None), (None, 'foo',)])
+
+    def test_on_conflict_rollback_without_transaction(self):
+        # Start of implicit transaction
+        self.cu.execute("INSERT INTO test(name) VALUES ('abort_test')")
+        self.cu.execute("INSERT OR ROLLBACK INTO test(unique_name) VALUES ('foo')")
+        with self.assertRaises(sqlite.IntegrityError):
+            self.cu.execute("INSERT OR ROLLBACK INTO test(unique_name) VALUES ('foo')")
+        self.cu.execute("SELECT name, unique_name FROM test")
+        # Implicit transaction is rolled back on error.
+        self.assertEqual(self.cu.fetchall(), [])
+
+    def test_on_conflict_abort_raises_without_transactions(self):
+        # Abort cancels the current sql statement but doesn't change anything
+        # about the current transaction.
+        self.cu.execute("INSERT INTO test(name) VALUES ('abort_test')")
+        self.cu.execute("INSERT OR ABORT INTO test(unique_name) VALUES ('foo')")
+        with self.assertRaises(sqlite.IntegrityError):
+            self.cu.execute("INSERT OR ABORT INTO test(unique_name) VALUES ('foo')")
+        # Make sure all other values were inserted.
+        self.cu.execute("SELECT name, unique_name FROM test")
+        self.assertEqual(self.cu.fetchall(), [('abort_test', None), (None, 'foo',)])
+
+    def test_on_conflict_fail(self):
+        self.cu.execute("INSERT OR FAIL INTO test(unique_name) VALUES ('foo')")
+        with self.assertRaises(sqlite.IntegrityError):
+            self.cu.execute("INSERT OR FAIL INTO test(unique_name) VALUES ('foo')")
+        self.assertEqual(self.cu.fetchall(), [])
+
+    def test_on_conflict_ignore(self):
+        self.cu.execute("INSERT OR IGNORE INTO test(unique_name) VALUES ('foo')")
+        # Nothing should happen.
+        self.cu.execute("INSERT OR IGNORE INTO test(unique_name) VALUES ('foo')")
+        self.cu.execute("SELECT unique_name FROM test")
+        self.assertEqual(self.cu.fetchall(), [('foo',)])
+
+    def test_on_conflict_replace(self):
+        self.cu.execute("INSERT OR REPLACE INTO test(name, unique_name) VALUES ('Data!', 'foo')")
+        # There shouldn't be an IntegrityError exception.
+        self.cu.execute("INSERT OR REPLACE INTO test(name, unique_name) VALUES ('Very different data!', 'foo')")
+        self.cu.execute("SELECT name, unique_name FROM test")
+        self.assertEqual(self.cu.fetchall(), [('Very different data!', 'foo')])
+
+
+class MultiprocessTests(unittest.TestCase):
+    CONNECTION_TIMEOUT = SHORT_TIMEOUT / 1000.  # Defaults to 30 ms
+
+    def tearDown(self):
+        unlink(TESTFN)
+
+    def test_ctx_mgr_rollback_if_commit_failed(self):
+        # bpo-27334: ctx manager does not rollback if commit fails
+        SCRIPT = f"""if 1:
+            import sqlite3
+            def wait():
+                print("started")
+                assert "database is locked" in input()
+
+            cx = sqlite3.connect("{TESTFN}", timeout={self.CONNECTION_TIMEOUT})
+            cx.create_function("wait", 0, wait)
+            with cx:
+                cx.execute("create table t(t)")
+            try:
+                # execute two transactions; both will try to lock the db
+                cx.executescript('''
+                    -- start a transaction and wait for parent
+                    begin transaction;
+                    select * from t;
+                    select wait();
+                    rollback;
+
+                    -- start a new transaction; would fail if parent holds lock
+                    begin transaction;
+                    select * from t;
+                    rollback;
+                ''')
+            finally:
+                cx.close()
+        """
+
+        # spawn child process
+        proc = subprocess.Popen(
+            [sys.executable, "-c", SCRIPT],
+            encoding="utf-8",
+            bufsize=0,
+            stdin=subprocess.PIPE,
+            stdout=subprocess.PIPE,
+        )
+        self.addCleanup(proc.communicate)
+
+        # wait for child process to start
+        self.assertEqual("started", proc.stdout.readline().strip())
+
+        cx = sqlite.connect(TESTFN, timeout=self.CONNECTION_TIMEOUT)
+        try:  # context manager should correctly release the db lock
+            with cx:
+                cx.execute("insert into t values('test')")
+        except sqlite.OperationalError as exc:
+            proc.stdin.write(str(exc))
+        else:
+            proc.stdin.write("no error")
+        finally:
+            cx.close()
+
+        # terminate child process
+        self.assertIsNone(proc.returncode)
+        try:
+            proc.communicate(input="end", timeout=SHORT_TIMEOUT)
+        except subprocess.TimeoutExpired:
+            proc.kill()
+            proc.communicate()
+            raise
+        self.assertEqual(proc.returncode, 0)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/Misc/NEWS.d/next/Library/2022-06-06-12-58-27.gh-issue-79579.e8rB-M.rst b/Misc/NEWS.d/next/Library/2022-06-06-12-58-27.gh-issue-79579.e8rB-M.rst
new file mode 100644
index 0000000..82b1a1c
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-06-06-12-58-27.gh-issue-79579.e8rB-M.rst
@@ -0,0 +1,2 @@
+:mod:`sqlite3` now correctly detects DML queries with leading comments.
+Patch by Erlend E. Aasland.
diff --git a/Modules/_sqlite/statement.c b/Modules/_sqlite/statement.c
index 3bc8642..adc531f 100644
--- a/Modules/_sqlite/statement.c
+++ b/Modules/_sqlite/statement.c
@@ -29,16 +29,7 @@
 #include "util.h"
 
 /* prototypes */
-static int pysqlite_check_remaining_sql(const char* tail);
-
-typedef enum {
-    LINECOMMENT_1,
-    IN_LINECOMMENT,
-    COMMENTSTART_1,
-    IN_COMMENT,
-    COMMENTEND_1,
-    NORMAL
-} parse_remaining_sql_state;
+static const char *lstrip_sql(const char *sql);
 
 typedef enum {
     TYPE_LONG,
@@ -55,7 +46,6 @@ pysqlite_statement_create(pysqlite_Connection *connection, PyObject *sql)
     int rc;
     const char* sql_cstr;
     Py_ssize_t sql_cstr_len;
-    const char* p;
 
     assert(PyUnicode_Check(sql));
 
@@ -87,20 +77,12 @@ pysqlite_statement_create(pysqlite_Connection *connection, PyObject *sql)
 
     /* Determine if the statement is a DML statement.
        SELECT is the only exception. See #9924. */
-    for (p = sql_cstr; *p != 0; p++) {
-        switch (*p) {
-            case ' ':
-            case '\r':
-            case '\n':
-            case '\t':
-                continue;
-        }
-
+    const char *p = lstrip_sql(sql_cstr);
+    if (p != NULL) {
         self->is_dml = (PyOS_strnicmp(p, "insert", 6) == 0)
                     || (PyOS_strnicmp(p, "update", 6) == 0)
                     || (PyOS_strnicmp(p, "delete", 6) == 0)
                     || (PyOS_strnicmp(p, "replace", 7) == 0);
-        break;
     }
 
     Py_BEGIN_ALLOW_THREADS
@@ -118,7 +100,7 @@ pysqlite_statement_create(pysqlite_Connection *connection, PyObject *sql)
         goto error;
     }
 
-    if (rc == SQLITE_OK && pysqlite_check_remaining_sql(tail)) {
+    if (rc == SQLITE_OK && lstrip_sql(tail)) {
         (void)sqlite3_finalize(self->st);
         self->st = NULL;
         PyErr_SetString(pysqlite_Warning,
@@ -431,73 +413,61 @@ stmt_traverse(pysqlite_Statement *self, visitproc visit, void *arg)
 }
 
 /*
- * Checks if there is anything left in an SQL string after SQLite compiled it.
- * This is used to check if somebody tried to execute more than one SQL command
- * with one execute()/executemany() command, which the DB-API and we don't
- * allow.
+ * Strip leading whitespace and comments from incoming SQL (null terminated C
+ * string) and return a pointer to the first non-whitespace, non-comment
+ * character.
+ *
+ * This is used to check if somebody tries to execute more than one SQL query
+ * with one execute()/executemany() command, which the DB-API don't allow.
  *
- * Returns 1 if there is more left than should be. 0 if ok.
+ * It is also used to harden DML query detection.
  */
-static int pysqlite_check_remaining_sql(const char* tail)
+static inline const char *
+lstrip_sql(const char *sql)
 {
-    const char* pos = tail;
-
-    parse_remaining_sql_state state = NORMAL;
-
-    for (;;) {
+    // This loop is borrowed from the SQLite source code.
+    for (const char *pos = sql; *pos; pos++) {
         switch (*pos) {
-            case 0:
-                return 0;
-            case '-':
-                if (state == NORMAL) {
-                    state  = LINECOMMENT_1;
-                } else if (state == LINECOMMENT_1) {
-                    state = IN_LINECOMMENT;
-                }
-                break;
             case ' ':
             case '\t':
-                break;
+            case '\f':
             case '\n':
-            case 13:
-                if (state == IN_LINECOMMENT) {
-                    state = NORMAL;
-                }
+            case '\r':
+                // Skip whitespace.
                 break;
-            case '/':
-                if (state == NORMAL) {
-                    state = COMMENTSTART_1;
-                } else if (state == COMMENTEND_1) {
-                    state = NORMAL;
-                } else if (state == COMMENTSTART_1) {
-                    return 1;
+            case '-':
+                // Skip line comments.
+                if (pos[1] == '-') {
+                    pos += 2;
+                    while (pos[0] && pos[0] != '\n') {
+                        pos++;
+                    }
+                    if (pos[0] == '\0') {
+                        return NULL;
+                    }
+                    continue;
                 }
-                break;
-            case '*':
-                if (state == NORMAL) {
-                    return 1;
-                } else if (state == LINECOMMENT_1) {
-                    return 1;
-                } else if (state == COMMENTSTART_1) {
-                    state = IN_COMMENT;
-                } else if (state == IN_COMMENT) {
-                    state = COMMENTEND_1;
+                return pos;
+            case '/':
+                // Skip C style comments.
+                if (pos[1] == '*') {
+                    pos += 2;
+                    while (pos[0] && (pos[0] != '*' || pos[1] != '/')) {
+                        pos++;
+                    }
+                    if (pos[0] == '\0') {
+                        return NULL;
+                    }
+                    pos++;
+                    continue;
                 }
-                break;
+                return pos;
             default:
-                if (state == COMMENTEND_1) {
-                    state = IN_COMMENT;
-                } else if (state == IN_LINECOMMENT) {
-                } else if (state == IN_COMMENT) {
-                } else {
-                    return 1;
-                }
+                return pos;
         }
-
-        pos++;
     }
 
-    return 0;
+    return NULL;
 }
 
 static PyMemberDef stmt_members[] = {