Adding upstream version 1.20.14.upstream/1.20.14upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 4585 insertions, 0 deletions

diff --git a/src/database/sql/sql_test.go b/src/database/sql/sql_test.go
new file mode 100644
index 0000000..8c58723
--- /dev/null
+++ b/src/database/sql/sql_test.go
@@ -0,0 +1,4585 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sql
+
+import (
+	"context"
+	"database/sql/driver"
+	"errors"
+	"fmt"
+	"math/rand"
+	"reflect"
+	"runtime"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+)
+
+func init() {
+	type dbConn struct {
+		db *DB
+		c  *driverConn
+	}
+	freedFrom := make(map[dbConn]string)
+	var mu sync.Mutex
+	getFreedFrom := func(c dbConn) string {
+		mu.Lock()
+		defer mu.Unlock()
+		return freedFrom[c]
+	}
+	setFreedFrom := func(c dbConn, s string) {
+		mu.Lock()
+		defer mu.Unlock()
+		freedFrom[c] = s
+	}
+	putConnHook = func(db *DB, c *driverConn) {
+		idx := -1
+		for i, v := range db.freeConn {
+			if v == c {
+				idx = i
+				break
+			}
+		}
+		if idx >= 0 {
+			// print before panic, as panic may get lost due to conflicting panic
+			// (all goroutines asleep) elsewhere, since we might not unlock
+			// the mutex in freeConn here.
+			println("double free of conn. conflicts are:\nA) " + getFreedFrom(dbConn{db, c}) + "\n\nand\nB) " + stack())
+			panic("double free of conn.")
+		}
+		setFreedFrom(dbConn{db, c}, stack())
+	}
+}
+
+// pollDuration is an arbitrary interval to wait between checks when polling for
+// a condition to occur.
+const pollDuration = 5 * time.Millisecond
+
+const fakeDBName = "foo"
+
+var chrisBirthday = time.Unix(123456789, 0)
+
+func newTestDB(t testing.TB, name string) *DB {
+	return newTestDBConnector(t, &fakeConnector{name: fakeDBName}, name)
+}
+
+func newTestDBConnector(t testing.TB, fc *fakeConnector, name string) *DB {
+	fc.name = fakeDBName
+	db := OpenDB(fc)
+	if _, err := db.Exec("WIPE"); err != nil {
+		t.Fatalf("exec wipe: %v", err)
+	}
+	if name == "people" {
+		exec(t, db, "CREATE|people|name=string,age=int32,photo=blob,dead=bool,bdate=datetime")
+		exec(t, db, "INSERT|people|name=Alice,age=?,photo=APHOTO", 1)
+		exec(t, db, "INSERT|people|name=Bob,age=?,photo=BPHOTO", 2)
+		exec(t, db, "INSERT|people|name=Chris,age=?,photo=CPHOTO,bdate=?", 3, chrisBirthday)
+	}
+	if name == "magicquery" {
+		// Magic table name and column, known by fakedb_test.go.
+		exec(t, db, "CREATE|magicquery|op=string,millis=int32")
+		exec(t, db, "INSERT|magicquery|op=sleep,millis=10")
+	}
+	if name == "tx_status" {
+		// Magic table name and column, known by fakedb_test.go.
+		exec(t, db, "CREATE|tx_status|tx_status=string")
+		exec(t, db, "INSERT|tx_status|tx_status=invalid")
+	}
+	return db
+}
+
+func TestOpenDB(t *testing.T) {
+	db := OpenDB(dsnConnector{dsn: fakeDBName, driver: fdriver})
+	if db.Driver() != fdriver {
+		t.Fatalf("OpenDB should return the driver of the Connector")
+	}
+}
+
+func TestDriverPanic(t *testing.T) {
+	// Test that if driver panics, database/sql does not deadlock.
+	db, err := Open("test", fakeDBName)
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	expectPanic := func(name string, f func()) {
+		defer func() {
+			err := recover()
+			if err == nil {
+				t.Fatalf("%s did not panic", name)
+			}
+		}()
+		f()
+	}
+
+	expectPanic("Exec Exec", func() { db.Exec("PANIC|Exec|WIPE") })
+	exec(t, db, "WIPE") // check not deadlocked
+	expectPanic("Exec NumInput", func() { db.Exec("PANIC|NumInput|WIPE") })
+	exec(t, db, "WIPE") // check not deadlocked
+	expectPanic("Exec Close", func() { db.Exec("PANIC|Close|WIPE") })
+	exec(t, db, "WIPE")             // check not deadlocked
+	exec(t, db, "PANIC|Query|WIPE") // should run successfully: Exec does not call Query
+	exec(t, db, "WIPE")             // check not deadlocked
+
+	exec(t, db, "CREATE|people|name=string,age=int32,photo=blob,dead=bool,bdate=datetime")
+
+	expectPanic("Query Query", func() { db.Query("PANIC|Query|SELECT|people|age,name|") })
+	expectPanic("Query NumInput", func() { db.Query("PANIC|NumInput|SELECT|people|age,name|") })
+	expectPanic("Query Close", func() {
+		rows, err := db.Query("PANIC|Close|SELECT|people|age,name|")
+		if err != nil {
+			t.Fatal(err)
+		}
+		rows.Close()
+	})
+	db.Query("PANIC|Exec|SELECT|people|age,name|") // should run successfully: Query does not call Exec
+	exec(t, db, "WIPE")                            // check not deadlocked
+}
+
+func exec(t testing.TB, db *DB, query string, args ...any) {
+	t.Helper()
+	_, err := db.Exec(query, args...)
+	if err != nil {
+		t.Fatalf("Exec of %q: %v", query, err)
+	}
+}
+
+func closeDB(t testing.TB, db *DB) {
+	if e := recover(); e != nil {
+		fmt.Printf("Panic: %v\n", e)
+		panic(e)
+	}
+	defer setHookpostCloseConn(nil)
+	setHookpostCloseConn(func(_ *fakeConn, err error) {
+		if err != nil {
+			t.Errorf("Error closing fakeConn: %v", err)
+		}
+	})
+	db.mu.Lock()
+	for i, dc := range db.freeConn {
+		if n := len(dc.openStmt); n > 0 {
+			// Just a sanity check. This is legal in
+			// general, but if we make the tests clean up
+			// their statements first, then we can safely
+			// verify this is always zero here, and any
+			// other value is a leak.
+			t.Errorf("while closing db, freeConn %d/%d had %d open stmts; want 0", i, len(db.freeConn), n)
+		}
+	}
+	db.mu.Unlock()
+
+	err := db.Close()
+	if err != nil {
+		t.Fatalf("error closing DB: %v", err)
+	}
+
+	var numOpen int
+	if !waitCondition(t, func() bool {
+		numOpen = db.numOpenConns()
+		return numOpen == 0
+	}) {
+		t.Fatalf("%d connections still open after closing DB", numOpen)
+	}
+}
+
+// numPrepares assumes that db has exactly 1 idle conn and returns
+// its count of calls to Prepare
+func numPrepares(t *testing.T, db *DB) int {
+	if n := len(db.freeConn); n != 1 {
+		t.Fatalf("free conns = %d; want 1", n)
+	}
+	return db.freeConn[0].ci.(*fakeConn).numPrepare
+}
+
+func (db *DB) numDeps() int {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	return len(db.dep)
+}
+
+// Dependencies are closed via a goroutine, so this polls waiting for
+// numDeps to fall to want, waiting up to nearly the test's deadline.
+func (db *DB) numDepsPoll(t *testing.T, want int) int {
+	var n int
+	waitCondition(t, func() bool {
+		n = db.numDeps()
+		return n <= want
+	})
+	return n
+}
+
+func (db *DB) numFreeConns() int {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	return len(db.freeConn)
+}
+
+func (db *DB) numOpenConns() int {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	return db.numOpen
+}
+
+// clearAllConns closes all connections in db.
+func (db *DB) clearAllConns(t *testing.T) {
+	db.SetMaxIdleConns(0)
+
+	if g, w := db.numFreeConns(), 0; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPoll(t, 0); n > 0 {
+		t.Errorf("number of dependencies = %d; expected 0", n)
+		db.dumpDeps(t)
+	}
+}
+
+func (db *DB) dumpDeps(t *testing.T) {
+	for fc := range db.dep {
+		db.dumpDep(t, 0, fc, map[finalCloser]bool{})
+	}
+}
+
+func (db *DB) dumpDep(t *testing.T, depth int, dep finalCloser, seen map[finalCloser]bool) {
+	seen[dep] = true
+	indent := strings.Repeat("  ", depth)
+	ds := db.dep[dep]
+	for k := range ds {
+		t.Logf("%s%T (%p) waiting for -> %T (%p)", indent, dep, dep, k, k)
+		if fc, ok := k.(finalCloser); ok {
+			if !seen[fc] {
+				db.dumpDep(t, depth+1, fc, seen)
+			}
+		}
+	}
+}
+
+func TestQuery(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	prepares0 := numPrepares(t, db)
+	rows, err := db.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+	type row struct {
+		age  int
+		name string
+	}
+	got := []row{}
+	for rows.Next() {
+		var r row
+		err = rows.Scan(&r.age, &r.name)
+		if err != nil {
+			t.Fatalf("Scan: %v", err)
+		}
+		got = append(got, r)
+	}
+	err = rows.Err()
+	if err != nil {
+		t.Fatalf("Err: %v", err)
+	}
+	want := []row{
+		{age: 1, name: "Alice"},
+		{age: 2, name: "Bob"},
+		{age: 3, name: "Chris"},
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("mismatch.\n got: %#v\nwant: %#v", got, want)
+	}
+
+	// And verify that the final rows.Next() call, which hit EOF,
+	// also closed the rows connection.
+	if n := db.numFreeConns(); n != 1 {
+		t.Fatalf("free conns after query hitting EOF = %d; want 1", n)
+	}
+	if prepares := numPrepares(t, db) - prepares0; prepares != 1 {
+		t.Errorf("executed %d Prepare statements; want 1", prepares)
+	}
+}
+
+// TestQueryContext tests canceling the context while scanning the rows.
+func TestQueryContext(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	prepares0 := numPrepares(t, db)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	rows, err := db.QueryContext(ctx, "SELECT|people|age,name|")
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+	type row struct {
+		age  int
+		name string
+	}
+	got := []row{}
+	index := 0
+	for rows.Next() {
+		if index == 2 {
+			cancel()
+			waitForRowsClose(t, rows)
+		}
+		var r row
+		err = rows.Scan(&r.age, &r.name)
+		if err != nil {
+			if index == 2 {
+				break
+			}
+			t.Fatalf("Scan: %v", err)
+		}
+		if index == 2 && err != context.Canceled {
+			t.Fatalf("Scan: %v; want context.Canceled", err)
+		}
+		got = append(got, r)
+		index++
+	}
+	select {
+	case <-ctx.Done():
+		if err := ctx.Err(); err != context.Canceled {
+			t.Fatalf("context err = %v; want context.Canceled", err)
+		}
+	default:
+		t.Fatalf("context err = nil; want context.Canceled")
+	}
+	want := []row{
+		{age: 1, name: "Alice"},
+		{age: 2, name: "Bob"},
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("mismatch.\n got: %#v\nwant: %#v", got, want)
+	}
+
+	// And verify that the final rows.Next() call, which hit EOF,
+	// also closed the rows connection.
+	waitForRowsClose(t, rows)
+	waitForFree(t, db, 1)
+	if prepares := numPrepares(t, db) - prepares0; prepares != 1 {
+		t.Errorf("executed %d Prepare statements; want 1", prepares)
+	}
+}
+
+func waitCondition(t testing.TB, fn func() bool) bool {
+	timeout := 5 * time.Second
+
+	type deadliner interface {
+		Deadline() (time.Time, bool)
+	}
+	if td, ok := t.(deadliner); ok {
+		if deadline, ok := td.Deadline(); ok {
+			timeout = time.Until(deadline)
+			timeout = timeout * 19 / 20 // Give 5% headroom for cleanup and error-reporting.
+		}
+	}
+
+	deadline := time.Now().Add(timeout)
+	for {
+		if fn() {
+			return true
+		}
+		if time.Until(deadline) < pollDuration {
+			return false
+		}
+		time.Sleep(pollDuration)
+	}
+}
+
+// waitForFree checks db.numFreeConns until either it equals want or
+// the maxWait time elapses.
+func waitForFree(t *testing.T, db *DB, want int) {
+	var numFree int
+	if !waitCondition(t, func() bool {
+		numFree = db.numFreeConns()
+		return numFree == want
+	}) {
+		t.Fatalf("free conns after hitting EOF = %d; want %d", numFree, want)
+	}
+}
+
+func waitForRowsClose(t *testing.T, rows *Rows) {
+	if !waitCondition(t, func() bool {
+		rows.closemu.RLock()
+		defer rows.closemu.RUnlock()
+		return rows.closed
+	}) {
+		t.Fatal("failed to close rows")
+	}
+}
+
+// TestQueryContextWait ensures that rows and all internal statements are closed when
+// a query context is closed during execution.
+func TestQueryContextWait(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	prepares0 := numPrepares(t, db)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	// This will trigger the *fakeConn.Prepare method which will take time
+	// performing the query. The ctxDriverPrepare func will check the context
+	// after this and close the rows and return an error.
+	c, err := db.Conn(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	c.dc.ci.(*fakeConn).waiter = func(c context.Context) {
+		cancel()
+		<-ctx.Done()
+	}
+	_, err = c.QueryContext(ctx, "SELECT|people|age,name|")
+	c.Close()
+	if err != context.Canceled {
+		t.Fatalf("expected QueryContext to error with context deadline exceeded but returned %v", err)
+	}
+
+	// Verify closed rows connection after error condition.
+	waitForFree(t, db, 1)
+	if prepares := numPrepares(t, db) - prepares0; prepares != 1 {
+		t.Fatalf("executed %d Prepare statements; want 1", prepares)
+	}
+}
+
+// TestTxContextWait tests the transaction behavior when the tx context is canceled
+// during execution of the query.
+func TestTxContextWait(t *testing.T) {
+	testContextWait(t, false)
+}
+
+// TestTxContextWaitNoDiscard is the same as TestTxContextWait, but should not discard
+// the final connection.
+func TestTxContextWaitNoDiscard(t *testing.T) {
+	testContextWait(t, true)
+}
+
+func testContextWait(t *testing.T, keepConnOnRollback bool) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	tx, err := db.BeginTx(ctx, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	tx.keepConnOnRollback = keepConnOnRollback
+
+	tx.dc.ci.(*fakeConn).waiter = func(c context.Context) {
+		cancel()
+		<-ctx.Done()
+	}
+	// This will trigger the *fakeConn.Prepare method which will take time
+	// performing the query. The ctxDriverPrepare func will check the context
+	// after this and close the rows and return an error.
+	_, err = tx.QueryContext(ctx, "SELECT|people|age,name|")
+	if err != context.Canceled {
+		t.Fatalf("expected QueryContext to error with context canceled but returned %v", err)
+	}
+
+	if keepConnOnRollback {
+		waitForFree(t, db, 1)
+	} else {
+		waitForFree(t, db, 0)
+	}
+}
+
+// TestUnsupportedOptions checks that the database fails when a driver that
+// doesn't implement ConnBeginTx is used with non-default options and an
+// un-cancellable context.
+func TestUnsupportedOptions(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	_, err := db.BeginTx(context.Background(), &TxOptions{
+		Isolation: LevelSerializable, ReadOnly: true,
+	})
+	if err == nil {
+		t.Fatal("expected error when using unsupported options, got nil")
+	}
+}
+
+func TestMultiResultSetQuery(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	prepares0 := numPrepares(t, db)
+	rows, err := db.Query("SELECT|people|age,name|;SELECT|people|name|")
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+	type row1 struct {
+		age  int
+		name string
+	}
+	type row2 struct {
+		name string
+	}
+	got1 := []row1{}
+	for rows.Next() {
+		var r row1
+		err = rows.Scan(&r.age, &r.name)
+		if err != nil {
+			t.Fatalf("Scan: %v", err)
+		}
+		got1 = append(got1, r)
+	}
+	err = rows.Err()
+	if err != nil {
+		t.Fatalf("Err: %v", err)
+	}
+	want1 := []row1{
+		{age: 1, name: "Alice"},
+		{age: 2, name: "Bob"},
+		{age: 3, name: "Chris"},
+	}
+	if !reflect.DeepEqual(got1, want1) {
+		t.Errorf("mismatch.\n got1: %#v\nwant: %#v", got1, want1)
+	}
+
+	if !rows.NextResultSet() {
+		t.Errorf("expected another result set")
+	}
+
+	got2 := []row2{}
+	for rows.Next() {
+		var r row2
+		err = rows.Scan(&r.name)
+		if err != nil {
+			t.Fatalf("Scan: %v", err)
+		}
+		got2 = append(got2, r)
+	}
+	err = rows.Err()
+	if err != nil {
+		t.Fatalf("Err: %v", err)
+	}
+	want2 := []row2{
+		{name: "Alice"},
+		{name: "Bob"},
+		{name: "Chris"},
+	}
+	if !reflect.DeepEqual(got2, want2) {
+		t.Errorf("mismatch.\n got: %#v\nwant: %#v", got2, want2)
+	}
+	if rows.NextResultSet() {
+		t.Errorf("expected no more result sets")
+	}
+
+	// And verify that the final rows.Next() call, which hit EOF,
+	// also closed the rows connection.
+	waitForFree(t, db, 1)
+	if prepares := numPrepares(t, db) - prepares0; prepares != 1 {
+		t.Errorf("executed %d Prepare statements; want 1", prepares)
+	}
+}
+
+func TestQueryNamedArg(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	prepares0 := numPrepares(t, db)
+	rows, err := db.Query(
+		// Ensure the name and age parameters only match on placeholder name, not position.
+		"SELECT|people|age,name|name=?name,age=?age",
+		Named("age", 2),
+		Named("name", "Bob"),
+	)
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+	type row struct {
+		age  int
+		name string
+	}
+	got := []row{}
+	for rows.Next() {
+		var r row
+		err = rows.Scan(&r.age, &r.name)
+		if err != nil {
+			t.Fatalf("Scan: %v", err)
+		}
+		got = append(got, r)
+	}
+	err = rows.Err()
+	if err != nil {
+		t.Fatalf("Err: %v", err)
+	}
+	want := []row{
+		{age: 2, name: "Bob"},
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("mismatch.\n got: %#v\nwant: %#v", got, want)
+	}
+
+	// And verify that the final rows.Next() call, which hit EOF,
+	// also closed the rows connection.
+	if n := db.numFreeConns(); n != 1 {
+		t.Fatalf("free conns after query hitting EOF = %d; want 1", n)
+	}
+	if prepares := numPrepares(t, db) - prepares0; prepares != 1 {
+		t.Errorf("executed %d Prepare statements; want 1", prepares)
+	}
+}
+
+func TestPoolExhaustOnCancel(t *testing.T) {
+	if testing.Short() {
+		t.Skip("long test")
+	}
+
+	max := 3
+	var saturate, saturateDone sync.WaitGroup
+	saturate.Add(max)
+	saturateDone.Add(max)
+
+	donePing := make(chan bool)
+	state := 0
+
+	// waiter will be called for all queries, including
+	// initial setup queries. The state is only assigned when
+	// no queries are made.
+	//
+	// Only allow the first batch of queries to finish once the
+	// second batch of Ping queries have finished.
+	waiter := func(ctx context.Context) {
+		switch state {
+		case 0:
+			// Nothing. Initial database setup.
+		case 1:
+			saturate.Done()
+			select {
+			case <-ctx.Done():
+			case <-donePing:
+			}
+		case 2:
+		}
+	}
+	db := newTestDBConnector(t, &fakeConnector{waiter: waiter}, "people")
+	defer closeDB(t, db)
+
+	db.SetMaxOpenConns(max)
+
+	// First saturate the connection pool.
+	// Then start new requests for a connection that is canceled after it is requested.
+
+	state = 1
+	for i := 0; i < max; i++ {
+		go func() {
+			rows, err := db.Query("SELECT|people|name,photo|")
+			if err != nil {
+				t.Errorf("Query: %v", err)
+				return
+			}
+			rows.Close()
+			saturateDone.Done()
+		}()
+	}
+
+	saturate.Wait()
+	if t.Failed() {
+		t.FailNow()
+	}
+	state = 2
+
+	// Now cancel the request while it is waiting.
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	for i := 0; i < max; i++ {
+		ctxReq, cancelReq := context.WithCancel(ctx)
+		go func() {
+			time.Sleep(100 * time.Millisecond)
+			cancelReq()
+		}()
+		err := db.PingContext(ctxReq)
+		if err != context.Canceled {
+			t.Fatalf("PingContext (Exhaust): %v", err)
+		}
+	}
+	close(donePing)
+	saturateDone.Wait()
+
+	// Now try to open a normal connection.
+	err := db.PingContext(ctx)
+	if err != nil {
+		t.Fatalf("PingContext (Normal): %v", err)
+	}
+}
+
+func TestRowsColumns(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	rows, err := db.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+	cols, err := rows.Columns()
+	if err != nil {
+		t.Fatalf("Columns: %v", err)
+	}
+	want := []string{"age", "name"}
+	if !reflect.DeepEqual(cols, want) {
+		t.Errorf("got %#v; want %#v", cols, want)
+	}
+	if err := rows.Close(); err != nil {
+		t.Errorf("error closing rows: %s", err)
+	}
+}
+
+func TestRowsColumnTypes(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	rows, err := db.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+	tt, err := rows.ColumnTypes()
+	if err != nil {
+		t.Fatalf("ColumnTypes: %v", err)
+	}
+
+	types := make([]reflect.Type, len(tt))
+	for i, tp := range tt {
+		st := tp.ScanType()
+		if st == nil {
+			t.Errorf("scantype is null for column %q", tp.Name())
+			continue
+		}
+		types[i] = st
+	}
+	values := make([]any, len(tt))
+	for i := range values {
+		values[i] = reflect.New(types[i]).Interface()
+	}
+	ct := 0
+	for rows.Next() {
+		err = rows.Scan(values...)
+		if err != nil {
+			t.Fatalf("failed to scan values in %v", err)
+		}
+		if ct == 1 {
+			if age := *values[0].(*int32); age != 2 {
+				t.Errorf("Expected 2, got %v", age)
+			}
+			if name := *values[1].(*string); name != "Bob" {
+				t.Errorf("Expected Bob, got %v", name)
+			}
+		}
+		ct++
+	}
+	if ct != 3 {
+		t.Errorf("expected 3 rows, got %d", ct)
+	}
+
+	if err := rows.Close(); err != nil {
+		t.Errorf("error closing rows: %s", err)
+	}
+}
+
+func TestQueryRow(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	var name string
+	var age int
+	var birthday time.Time
+
+	err := db.QueryRow("SELECT|people|age,name|age=?", 3).Scan(&age)
+	if err == nil || !strings.Contains(err.Error(), "expected 2 destination arguments") {
+		t.Errorf("expected error from wrong number of arguments; actually got: %v", err)
+	}
+
+	err = db.QueryRow("SELECT|people|bdate|age=?", 3).Scan(&birthday)
+	if err != nil || !birthday.Equal(chrisBirthday) {
+		t.Errorf("chris birthday = %v, err = %v; want %v", birthday, err, chrisBirthday)
+	}
+
+	err = db.QueryRow("SELECT|people|age,name|age=?", 2).Scan(&age, &name)
+	if err != nil {
+		t.Fatalf("age QueryRow+Scan: %v", err)
+	}
+	if name != "Bob" {
+		t.Errorf("expected name Bob, got %q", name)
+	}
+	if age != 2 {
+		t.Errorf("expected age 2, got %d", age)
+	}
+
+	err = db.QueryRow("SELECT|people|age,name|name=?", "Alice").Scan(&age, &name)
+	if err != nil {
+		t.Fatalf("name QueryRow+Scan: %v", err)
+	}
+	if name != "Alice" {
+		t.Errorf("expected name Alice, got %q", name)
+	}
+	if age != 1 {
+		t.Errorf("expected age 1, got %d", age)
+	}
+
+	var photo []byte
+	err = db.QueryRow("SELECT|people|photo|name=?", "Alice").Scan(&photo)
+	if err != nil {
+		t.Fatalf("photo QueryRow+Scan: %v", err)
+	}
+	want := []byte("APHOTO")
+	if !reflect.DeepEqual(photo, want) {
+		t.Errorf("photo = %q; want %q", photo, want)
+	}
+}
+
+func TestRowErr(t *testing.T) {
+	db := newTestDB(t, "people")
+
+	err := db.QueryRowContext(context.Background(), "SELECT|people|bdate|age=?", 3).Err()
+	if err != nil {
+		t.Errorf("Unexpected err = %v; want %v", err, nil)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	err = db.QueryRowContext(ctx, "SELECT|people|bdate|age=?", 3).Err()
+	exp := "context canceled"
+	if err == nil || !strings.Contains(err.Error(), exp) {
+		t.Errorf("Expected err = %v; got %v", exp, err)
+	}
+}
+
+func TestTxRollbackCommitErr(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = tx.Rollback()
+	if err != nil {
+		t.Errorf("expected nil error from Rollback; got %v", err)
+	}
+	err = tx.Commit()
+	if err != ErrTxDone {
+		t.Errorf("expected %q from Commit; got %q", ErrTxDone, err)
+	}
+
+	tx, err = db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = tx.Commit()
+	if err != nil {
+		t.Errorf("expected nil error from Commit; got %v", err)
+	}
+	err = tx.Rollback()
+	if err != ErrTxDone {
+		t.Errorf("expected %q from Rollback; got %q", ErrTxDone, err)
+	}
+}
+
+func TestStatementErrorAfterClose(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	stmt, err := db.Prepare("SELECT|people|age|name=?")
+	if err != nil {
+		t.Fatalf("Prepare: %v", err)
+	}
+	err = stmt.Close()
+	if err != nil {
+		t.Fatalf("Close: %v", err)
+	}
+	var name string
+	err = stmt.QueryRow("foo").Scan(&name)
+	if err == nil {
+		t.Errorf("expected error from QueryRow.Scan after Stmt.Close")
+	}
+}
+
+func TestStatementQueryRow(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	stmt, err := db.Prepare("SELECT|people|age|name=?")
+	if err != nil {
+		t.Fatalf("Prepare: %v", err)
+	}
+	defer stmt.Close()
+	var age int
+	for n, tt := range []struct {
+		name string
+		want int
+	}{
+		{"Alice", 1},
+		{"Bob", 2},
+		{"Chris", 3},
+	} {
+		if err := stmt.QueryRow(tt.name).Scan(&age); err != nil {
+			t.Errorf("%d: on %q, QueryRow/Scan: %v", n, tt.name, err)
+		} else if age != tt.want {
+			t.Errorf("%d: age=%d, want %d", n, age, tt.want)
+		}
+	}
+}
+
+type stubDriverStmt struct {
+	err error
+}
+
+func (s stubDriverStmt) Close() error {
+	return s.err
+}
+
+func (s stubDriverStmt) NumInput() int {
+	return -1
+}
+
+func (s stubDriverStmt) Exec(args []driver.Value) (driver.Result, error) {
+	return nil, nil
+}
+
+func (s stubDriverStmt) Query(args []driver.Value) (driver.Rows, error) {
+	return nil, nil
+}
+
+// golang.org/issue/12798
+func TestStatementClose(t *testing.T) {
+	want := errors.New("STMT ERROR")
+
+	tests := []struct {
+		stmt *Stmt
+		msg  string
+	}{
+		{&Stmt{stickyErr: want}, "stickyErr not propagated"},
+		{&Stmt{cg: &Tx{}, cgds: &driverStmt{Locker: &sync.Mutex{}, si: stubDriverStmt{want}}}, "driverStmt.Close() error not propagated"},
+	}
+	for _, test := range tests {
+		if err := test.stmt.Close(); err != want {
+			t.Errorf("%s. Got stmt.Close() = %v, want = %v", test.msg, err, want)
+		}
+	}
+}
+
+// golang.org/issue/3734
+func TestStatementQueryRowConcurrent(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	stmt, err := db.Prepare("SELECT|people|age|name=?")
+	if err != nil {
+		t.Fatalf("Prepare: %v", err)
+	}
+	defer stmt.Close()
+
+	const n = 10
+	ch := make(chan error, n)
+	for i := 0; i < n; i++ {
+		go func() {
+			var age int
+			err := stmt.QueryRow("Alice").Scan(&age)
+			if err == nil && age != 1 {
+				err = fmt.Errorf("unexpected age %d", age)
+			}
+			ch <- err
+		}()
+	}
+	for i := 0; i < n; i++ {
+		if err := <-ch; err != nil {
+			t.Error(err)
+		}
+	}
+}
+
+// just a test of fakedb itself
+func TestBogusPreboundParameters(t *testing.T) {
+	db := newTestDB(t, "foo")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	_, err := db.Prepare("INSERT|t1|name=?,age=bogusconversion")
+	if err == nil {
+		t.Fatalf("expected error")
+	}
+	if err.Error() != `fakedb: invalid conversion to int32 from "bogusconversion"` {
+		t.Errorf("unexpected error: %v", err)
+	}
+}
+
+func TestExec(t *testing.T) {
+	db := newTestDB(t, "foo")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	stmt, err := db.Prepare("INSERT|t1|name=?,age=?")
+	if err != nil {
+		t.Errorf("Stmt, err = %v, %v", stmt, err)
+	}
+	defer stmt.Close()
+
+	type execTest struct {
+		args    []any
+		wantErr string
+	}
+	execTests := []execTest{
+		// Okay:
+		{[]any{"Brad", 31}, ""},
+		{[]any{"Brad", int64(31)}, ""},
+		{[]any{"Bob", "32"}, ""},
+		{[]any{7, 9}, ""},
+
+		// Invalid conversions:
+		{[]any{"Brad", int64(0xFFFFFFFF)}, "sql: converting argument $2 type: sql/driver: value 4294967295 overflows int32"},
+		{[]any{"Brad", "strconv fail"}, `sql: converting argument $2 type: sql/driver: value "strconv fail" can't be converted to int32`},
+
+		// Wrong number of args:
+		{[]any{}, "sql: expected 2 arguments, got 0"},
+		{[]any{1, 2, 3}, "sql: expected 2 arguments, got 3"},
+	}
+	for n, et := range execTests {
+		_, err := stmt.Exec(et.args...)
+		errStr := ""
+		if err != nil {
+			errStr = err.Error()
+		}
+		if errStr != et.wantErr {
+			t.Errorf("stmt.Execute #%d: for %v, got error %q, want error %q",
+				n, et.args, errStr, et.wantErr)
+		}
+	}
+}
+
+func TestTxPrepare(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatalf("Begin = %v", err)
+	}
+	stmt, err := tx.Prepare("INSERT|t1|name=?,age=?")
+	if err != nil {
+		t.Fatalf("Stmt, err = %v, %v", stmt, err)
+	}
+	defer stmt.Close()
+	_, err = stmt.Exec("Bobby", 7)
+	if err != nil {
+		t.Fatalf("Exec = %v", err)
+	}
+	err = tx.Commit()
+	if err != nil {
+		t.Fatalf("Commit = %v", err)
+	}
+	// Commit() should have closed the statement
+	if !stmt.closed {
+		t.Fatal("Stmt not closed after Commit")
+	}
+}
+
+func TestTxStmt(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	stmt, err := db.Prepare("INSERT|t1|name=?,age=?")
+	if err != nil {
+		t.Fatalf("Stmt, err = %v, %v", stmt, err)
+	}
+	defer stmt.Close()
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatalf("Begin = %v", err)
+	}
+	txs := tx.Stmt(stmt)
+	defer txs.Close()
+	_, err = txs.Exec("Bobby", 7)
+	if err != nil {
+		t.Fatalf("Exec = %v", err)
+	}
+	err = tx.Commit()
+	if err != nil {
+		t.Fatalf("Commit = %v", err)
+	}
+	// Commit() should have closed the statement
+	if !txs.closed {
+		t.Fatal("Stmt not closed after Commit")
+	}
+}
+
+func TestTxStmtPreparedOnce(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32")
+
+	prepares0 := numPrepares(t, db)
+
+	// db.Prepare increments numPrepares.
+	stmt, err := db.Prepare("INSERT|t1|name=?,age=?")
+	if err != nil {
+		t.Fatalf("Stmt, err = %v, %v", stmt, err)
+	}
+	defer stmt.Close()
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatalf("Begin = %v", err)
+	}
+
+	txs1 := tx.Stmt(stmt)
+	txs2 := tx.Stmt(stmt)
+
+	_, err = txs1.Exec("Go", 7)
+	if err != nil {
+		t.Fatalf("Exec = %v", err)
+	}
+	txs1.Close()
+
+	_, err = txs2.Exec("Gopher", 8)
+	if err != nil {
+		t.Fatalf("Exec = %v", err)
+	}
+	txs2.Close()
+
+	err = tx.Commit()
+	if err != nil {
+		t.Fatalf("Commit = %v", err)
+	}
+
+	if prepares := numPrepares(t, db) - prepares0; prepares != 1 {
+		t.Errorf("executed %d Prepare statements; want 1", prepares)
+	}
+}
+
+func TestTxStmtClosedRePrepares(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32")
+
+	prepares0 := numPrepares(t, db)
+
+	// db.Prepare increments numPrepares.
+	stmt, err := db.Prepare("INSERT|t1|name=?,age=?")
+	if err != nil {
+		t.Fatalf("Stmt, err = %v, %v", stmt, err)
+	}
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatalf("Begin = %v", err)
+	}
+	err = stmt.Close()
+	if err != nil {
+		t.Fatalf("stmt.Close() = %v", err)
+	}
+	// tx.Stmt increments numPrepares because stmt is closed.
+	txs := tx.Stmt(stmt)
+	if txs.stickyErr != nil {
+		t.Fatal(txs.stickyErr)
+	}
+	if txs.parentStmt != nil {
+		t.Fatal("expected nil parentStmt")
+	}
+	_, err = txs.Exec(`Eric`, 82)
+	if err != nil {
+		t.Fatalf("txs.Exec = %v", err)
+	}
+
+	err = txs.Close()
+	if err != nil {
+		t.Fatalf("txs.Close = %v", err)
+	}
+
+	tx.Rollback()
+
+	if prepares := numPrepares(t, db) - prepares0; prepares != 2 {
+		t.Errorf("executed %d Prepare statements; want 2", prepares)
+	}
+}
+
+func TestParentStmtOutlivesTxStmt(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32")
+
+	// Make sure everything happens on the same connection.
+	db.SetMaxOpenConns(1)
+
+	prepares0 := numPrepares(t, db)
+
+	// db.Prepare increments numPrepares.
+	stmt, err := db.Prepare("INSERT|t1|name=?,age=?")
+	if err != nil {
+		t.Fatalf("Stmt, err = %v, %v", stmt, err)
+	}
+	defer stmt.Close()
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatalf("Begin = %v", err)
+	}
+	txs := tx.Stmt(stmt)
+	if len(stmt.css) != 1 {
+		t.Fatalf("len(stmt.css) = %v; want 1", len(stmt.css))
+	}
+	err = txs.Close()
+	if err != nil {
+		t.Fatalf("txs.Close() = %v", err)
+	}
+	err = tx.Rollback()
+	if err != nil {
+		t.Fatalf("tx.Rollback() = %v", err)
+	}
+	// txs must not be valid.
+	_, err = txs.Exec("Suzan", 30)
+	if err == nil {
+		t.Fatalf("txs.Exec(), expected err")
+	}
+	// Stmt must still be valid.
+	_, err = stmt.Exec("Janina", 25)
+	if err != nil {
+		t.Fatalf("stmt.Exec() = %v", err)
+	}
+
+	if prepares := numPrepares(t, db) - prepares0; prepares != 1 {
+		t.Errorf("executed %d Prepare statements; want 1", prepares)
+	}
+}
+
+// Test that tx.Stmt called with a statement already
+// associated with tx as argument re-prepares the same
+// statement again.
+func TestTxStmtFromTxStmtRePrepares(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32")
+	prepares0 := numPrepares(t, db)
+	// db.Prepare increments numPrepares.
+	stmt, err := db.Prepare("INSERT|t1|name=?,age=?")
+	if err != nil {
+		t.Fatalf("Stmt, err = %v, %v", stmt, err)
+	}
+	defer stmt.Close()
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatalf("Begin = %v", err)
+	}
+	txs1 := tx.Stmt(stmt)
+
+	// tx.Stmt(txs1) increments numPrepares because txs1 already
+	// belongs to a transaction (albeit the same transaction).
+	txs2 := tx.Stmt(txs1)
+	if txs2.stickyErr != nil {
+		t.Fatal(txs2.stickyErr)
+	}
+	if txs2.parentStmt != nil {
+		t.Fatal("expected nil parentStmt")
+	}
+	_, err = txs2.Exec(`Eric`, 82)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = txs1.Close()
+	if err != nil {
+		t.Fatalf("txs1.Close = %v", err)
+	}
+	err = txs2.Close()
+	if err != nil {
+		t.Fatalf("txs1.Close = %v", err)
+	}
+	err = tx.Rollback()
+	if err != nil {
+		t.Fatalf("tx.Rollback = %v", err)
+	}
+
+	if prepares := numPrepares(t, db) - prepares0; prepares != 2 {
+		t.Errorf("executed %d Prepare statements; want 2", prepares)
+	}
+}
+
+// Issue: https://golang.org/issue/2784
+// This test didn't fail before because we got lucky with the fakedb driver.
+// It was failing, and now not, in github.com/bradfitz/go-sql-test
+func TestTxQuery(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	exec(t, db, "INSERT|t1|name=Alice")
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer tx.Rollback()
+
+	r, err := tx.Query("SELECT|t1|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer r.Close()
+
+	if !r.Next() {
+		if r.Err() != nil {
+			t.Fatal(r.Err())
+		}
+		t.Fatal("expected one row")
+	}
+
+	var x string
+	err = r.Scan(&x)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestTxQueryInvalid(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer tx.Rollback()
+
+	_, err = tx.Query("SELECT|t1|name|")
+	if err == nil {
+		t.Fatal("Error expected")
+	}
+}
+
+// Tests fix for issue 4433, that retries in Begin happen when
+// conn.Begin() returns ErrBadConn
+func TestTxErrBadConn(t *testing.T) {
+	db, err := Open("test", fakeDBName+";badConn")
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	if _, err := db.Exec("WIPE"); err != nil {
+		t.Fatalf("exec wipe: %v", err)
+	}
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	stmt, err := db.Prepare("INSERT|t1|name=?,age=?")
+	if err != nil {
+		t.Fatalf("Stmt, err = %v, %v", stmt, err)
+	}
+	defer stmt.Close()
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatalf("Begin = %v", err)
+	}
+	txs := tx.Stmt(stmt)
+	defer txs.Close()
+	_, err = txs.Exec("Bobby", 7)
+	if err != nil {
+		t.Fatalf("Exec = %v", err)
+	}
+	err = tx.Commit()
+	if err != nil {
+		t.Fatalf("Commit = %v", err)
+	}
+}
+
+func TestConnQuery(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	conn, err := db.Conn(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	conn.dc.ci.(*fakeConn).skipDirtySession = true
+	defer conn.Close()
+
+	var name string
+	err = conn.QueryRowContext(ctx, "SELECT|people|name|age=?", 3).Scan(&name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if name != "Chris" {
+		t.Fatalf("unexpected result, got %q want Chris", name)
+	}
+
+	err = conn.PingContext(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestConnRaw(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	conn, err := db.Conn(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	conn.dc.ci.(*fakeConn).skipDirtySession = true
+	defer conn.Close()
+
+	sawFunc := false
+	err = conn.Raw(func(dc any) error {
+		sawFunc = true
+		if _, ok := dc.(*fakeConn); !ok {
+			return fmt.Errorf("got %T want *fakeConn", dc)
+		}
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !sawFunc {
+		t.Fatal("Raw func not called")
+	}
+
+	func() {
+		defer func() {
+			x := recover()
+			if x == nil {
+				t.Fatal("expected panic")
+			}
+			conn.closemu.Lock()
+			closed := conn.dc == nil
+			conn.closemu.Unlock()
+			if !closed {
+				t.Fatal("expected connection to be closed after panic")
+			}
+		}()
+		err = conn.Raw(func(dc any) error {
+			panic("Conn.Raw panic should return an error")
+		})
+		t.Fatal("expected panic from Raw func")
+	}()
+}
+
+func TestCursorFake(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*30)
+	defer cancel()
+
+	exec(t, db, "CREATE|peoplecursor|list=table")
+	exec(t, db, "INSERT|peoplecursor|list=people!name!age")
+
+	rows, err := db.QueryContext(ctx, `SELECT|peoplecursor|list|`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer rows.Close()
+
+	if !rows.Next() {
+		t.Fatal("no rows")
+	}
+	var cursor = &Rows{}
+	err = rows.Scan(cursor)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer cursor.Close()
+
+	const expectedRows = 3
+	var currentRow int64
+
+	var n int64
+	var s string
+	for cursor.Next() {
+		currentRow++
+		err = cursor.Scan(&s, &n)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if n != currentRow {
+			t.Errorf("expected number(Age)=%d, got %d", currentRow, n)
+		}
+	}
+	if currentRow != expectedRows {
+		t.Errorf("expected %d rows, got %d rows", expectedRows, currentRow)
+	}
+}
+
+func TestInvalidNilValues(t *testing.T) {
+	var date1 time.Time
+	var date2 int
+
+	tests := []struct {
+		name          string
+		input         any
+		expectedError string
+	}{
+		{
+			name:          "time.Time",
+			input:         &date1,
+			expectedError: `sql: Scan error on column index 0, name "bdate": unsupported Scan, storing driver.Value type <nil> into type *time.Time`,
+		},
+		{
+			name:          "int",
+			input:         &date2,
+			expectedError: `sql: Scan error on column index 0, name "bdate": converting NULL to int is unsupported`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			db := newTestDB(t, "people")
+			defer closeDB(t, db)
+
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+			conn, err := db.Conn(ctx)
+			if err != nil {
+				t.Fatal(err)
+			}
+			conn.dc.ci.(*fakeConn).skipDirtySession = true
+			defer conn.Close()
+
+			err = conn.QueryRowContext(ctx, "SELECT|people|bdate|age=?", 1).Scan(tt.input)
+			if err == nil {
+				t.Fatal("expected error when querying nil column, but succeeded")
+			}
+			if err.Error() != tt.expectedError {
+				t.Fatalf("Expected error: %s\nReceived: %s", tt.expectedError, err.Error())
+			}
+
+			err = conn.PingContext(ctx)
+			if err != nil {
+				t.Fatal(err)
+			}
+		})
+	}
+}
+
+func TestConnTx(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	conn, err := db.Conn(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	conn.dc.ci.(*fakeConn).skipDirtySession = true
+	defer conn.Close()
+
+	tx, err := conn.BeginTx(ctx, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	insertName, insertAge := "Nancy", 33
+	_, err = tx.ExecContext(ctx, "INSERT|people|name=?,age=?,photo=APHOTO", insertName, insertAge)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = tx.Commit()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var selectName string
+	err = conn.QueryRowContext(ctx, "SELECT|people|name|age=?", insertAge).Scan(&selectName)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if selectName != insertName {
+		t.Fatalf("got %q want %q", selectName, insertName)
+	}
+}
+
+// TestConnIsValid verifies that a database connection that should be discarded,
+// is actually discarded and does not re-enter the connection pool.
+// If the IsValid method from *fakeConn is removed, this test will fail.
+func TestConnIsValid(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	db.SetMaxOpenConns(1)
+
+	ctx := context.Background()
+
+	c, err := db.Conn(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = c.Raw(func(raw any) error {
+		dc := raw.(*fakeConn)
+		dc.stickyBad = true
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	c.Close()
+
+	if len(db.freeConn) > 0 && db.freeConn[0].ci.(*fakeConn).stickyBad {
+		t.Fatal("bad connection returned to pool; expected bad connection to be discarded")
+	}
+}
+
+// Tests fix for issue 2542, that we release a lock when querying on
+// a closed connection.
+func TestIssue2542Deadlock(t *testing.T) {
+	db := newTestDB(t, "people")
+	closeDB(t, db)
+	for i := 0; i < 2; i++ {
+		_, err := db.Query("SELECT|people|age,name|")
+		if err == nil {
+			t.Fatalf("expected error")
+		}
+	}
+}
+
+// From golang.org/issue/3865
+func TestCloseStmtBeforeRows(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	s, err := db.Prepare("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	r, err := s.Query()
+	if err != nil {
+		s.Close()
+		t.Fatal(err)
+	}
+
+	err = s.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	r.Close()
+}
+
+// Tests fix for issue 2788, that we bind nil to a []byte if the
+// value in the column is sql null
+func TestNullByteSlice(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t|id=int32,name=nullstring")
+	exec(t, db, "INSERT|t|id=10,name=?", nil)
+
+	var name []byte
+
+	err := db.QueryRow("SELECT|t|name|id=?", 10).Scan(&name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if name != nil {
+		t.Fatalf("name []byte should be nil for null column value, got: %#v", name)
+	}
+
+	exec(t, db, "INSERT|t|id=11,name=?", "bob")
+	err = db.QueryRow("SELECT|t|name|id=?", 11).Scan(&name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(name) != "bob" {
+		t.Fatalf("name []byte should be bob, got: %q", string(name))
+	}
+}
+
+func TestPointerParamsAndScans(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t|id=int32,name=nullstring")
+
+	bob := "bob"
+	var name *string
+
+	name = &bob
+	exec(t, db, "INSERT|t|id=10,name=?", name)
+	name = nil
+	exec(t, db, "INSERT|t|id=20,name=?", name)
+
+	err := db.QueryRow("SELECT|t|name|id=?", 10).Scan(&name)
+	if err != nil {
+		t.Fatalf("querying id 10: %v", err)
+	}
+	if name == nil {
+		t.Errorf("id 10's name = nil; want bob")
+	} else if *name != "bob" {
+		t.Errorf("id 10's name = %q; want bob", *name)
+	}
+
+	err = db.QueryRow("SELECT|t|name|id=?", 20).Scan(&name)
+	if err != nil {
+		t.Fatalf("querying id 20: %v", err)
+	}
+	if name != nil {
+		t.Errorf("id 20 = %q; want nil", *name)
+	}
+}
+
+func TestQueryRowClosingStmt(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	var name string
+	var age int
+	err := db.QueryRow("SELECT|people|age,name|age=?", 3).Scan(&age, &name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(db.freeConn) != 1 {
+		t.Fatalf("expected 1 free conn")
+	}
+	fakeConn := db.freeConn[0].ci.(*fakeConn)
+	if made, closed := fakeConn.stmtsMade, fakeConn.stmtsClosed; made != closed {
+		t.Errorf("statement close mismatch: made %d, closed %d", made, closed)
+	}
+}
+
+var atomicRowsCloseHook atomic.Value // of func(*Rows, *error)
+
+func init() {
+	rowsCloseHook = func() func(*Rows, *error) {
+		fn, _ := atomicRowsCloseHook.Load().(func(*Rows, *error))
+		return fn
+	}
+}
+
+func setRowsCloseHook(fn func(*Rows, *error)) {
+	if fn == nil {
+		// Can't change an atomic.Value back to nil, so set it to this
+		// no-op func instead.
+		fn = func(*Rows, *error) {}
+	}
+	atomicRowsCloseHook.Store(fn)
+}
+
+// Test issue 6651
+func TestIssue6651(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	var v string
+
+	want := "error in rows.Next"
+	rowsCursorNextHook = func(dest []driver.Value) error {
+		return fmt.Errorf(want)
+	}
+	defer func() { rowsCursorNextHook = nil }()
+
+	err := db.QueryRow("SELECT|people|name|").Scan(&v)
+	if err == nil || err.Error() != want {
+		t.Errorf("error = %q; want %q", err, want)
+	}
+	rowsCursorNextHook = nil
+
+	want = "error in rows.Close"
+	setRowsCloseHook(func(rows *Rows, err *error) {
+		*err = fmt.Errorf(want)
+	})
+	defer setRowsCloseHook(nil)
+	err = db.QueryRow("SELECT|people|name|").Scan(&v)
+	if err == nil || err.Error() != want {
+		t.Errorf("error = %q; want %q", err, want)
+	}
+}
+
+type nullTestRow struct {
+	nullParam    any
+	notNullParam any
+	scanNullVal  any
+}
+
+type nullTestSpec struct {
+	nullType    string
+	notNullType string
+	rows        [6]nullTestRow
+}
+
+func TestNullStringParam(t *testing.T) {
+	spec := nullTestSpec{"nullstring", "string", [6]nullTestRow{
+		{NullString{"aqua", true}, "", NullString{"aqua", true}},
+		{NullString{"brown", false}, "", NullString{"", false}},
+		{"chartreuse", "", NullString{"chartreuse", true}},
+		{NullString{"darkred", true}, "", NullString{"darkred", true}},
+		{NullString{"eel", false}, "", NullString{"", false}},
+		{"foo", NullString{"black", false}, nil},
+	}}
+	nullTestRun(t, spec)
+}
+
+func TestNullInt64Param(t *testing.T) {
+	spec := nullTestSpec{"nullint64", "int64", [6]nullTestRow{
+		{NullInt64{31, true}, 1, NullInt64{31, true}},
+		{NullInt64{-22, false}, 1, NullInt64{0, false}},
+		{22, 1, NullInt64{22, true}},
+		{NullInt64{33, true}, 1, NullInt64{33, true}},
+		{NullInt64{222, false}, 1, NullInt64{0, false}},
+		{0, NullInt64{31, false}, nil},
+	}}
+	nullTestRun(t, spec)
+}
+
+func TestNullInt32Param(t *testing.T) {
+	spec := nullTestSpec{"nullint32", "int32", [6]nullTestRow{
+		{NullInt32{31, true}, 1, NullInt32{31, true}},
+		{NullInt32{-22, false}, 1, NullInt32{0, false}},
+		{22, 1, NullInt32{22, true}},
+		{NullInt32{33, true}, 1, NullInt32{33, true}},
+		{NullInt32{222, false}, 1, NullInt32{0, false}},
+		{0, NullInt32{31, false}, nil},
+	}}
+	nullTestRun(t, spec)
+}
+
+func TestNullInt16Param(t *testing.T) {
+	spec := nullTestSpec{"nullint16", "int16", [6]nullTestRow{
+		{NullInt16{31, true}, 1, NullInt16{31, true}},
+		{NullInt16{-22, false}, 1, NullInt16{0, false}},
+		{22, 1, NullInt16{22, true}},
+		{NullInt16{33, true}, 1, NullInt16{33, true}},
+		{NullInt16{222, false}, 1, NullInt16{0, false}},
+		{0, NullInt16{31, false}, nil},
+	}}
+	nullTestRun(t, spec)
+}
+
+func TestNullByteParam(t *testing.T) {
+	spec := nullTestSpec{"nullbyte", "byte", [6]nullTestRow{
+		{NullByte{31, true}, 1, NullByte{31, true}},
+		{NullByte{0, false}, 1, NullByte{0, false}},
+		{22, 1, NullByte{22, true}},
+		{NullByte{33, true}, 1, NullByte{33, true}},
+		{NullByte{222, false}, 1, NullByte{0, false}},
+		{0, NullByte{31, false}, nil},
+	}}
+	nullTestRun(t, spec)
+}
+
+func TestNullFloat64Param(t *testing.T) {
+	spec := nullTestSpec{"nullfloat64", "float64", [6]nullTestRow{
+		{NullFloat64{31.2, true}, 1, NullFloat64{31.2, true}},
+		{NullFloat64{13.1, false}, 1, NullFloat64{0, false}},
+		{-22.9, 1, NullFloat64{-22.9, true}},
+		{NullFloat64{33.81, true}, 1, NullFloat64{33.81, true}},
+		{NullFloat64{222, false}, 1, NullFloat64{0, false}},
+		{10, NullFloat64{31.2, false}, nil},
+	}}
+	nullTestRun(t, spec)
+}
+
+func TestNullBoolParam(t *testing.T) {
+	spec := nullTestSpec{"nullbool", "bool", [6]nullTestRow{
+		{NullBool{false, true}, true, NullBool{false, true}},
+		{NullBool{true, false}, false, NullBool{false, false}},
+		{true, true, NullBool{true, true}},
+		{NullBool{true, true}, false, NullBool{true, true}},
+		{NullBool{true, false}, true, NullBool{false, false}},
+		{true, NullBool{true, false}, nil},
+	}}
+	nullTestRun(t, spec)
+}
+
+func TestNullTimeParam(t *testing.T) {
+	t0 := time.Time{}
+	t1 := time.Date(2000, 1, 1, 8, 9, 10, 11, time.UTC)
+	t2 := time.Date(2010, 1, 1, 8, 9, 10, 11, time.UTC)
+	spec := nullTestSpec{"nulldatetime", "datetime", [6]nullTestRow{
+		{NullTime{t1, true}, t2, NullTime{t1, true}},
+		{NullTime{t1, false}, t2, NullTime{t0, false}},
+		{t1, t2, NullTime{t1, true}},
+		{NullTime{t1, true}, t2, NullTime{t1, true}},
+		{NullTime{t1, false}, t2, NullTime{t0, false}},
+		{t2, NullTime{t1, false}, nil},
+	}}
+	nullTestRun(t, spec)
+}
+
+func nullTestRun(t *testing.T, spec nullTestSpec) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, fmt.Sprintf("CREATE|t|id=int32,name=string,nullf=%s,notnullf=%s", spec.nullType, spec.notNullType))
+
+	// Inserts with db.Exec:
+	exec(t, db, "INSERT|t|id=?,name=?,nullf=?,notnullf=?", 1, "alice", spec.rows[0].nullParam, spec.rows[0].notNullParam)
+	exec(t, db, "INSERT|t|id=?,name=?,nullf=?,notnullf=?", 2, "bob", spec.rows[1].nullParam, spec.rows[1].notNullParam)
+
+	// Inserts with a prepared statement:
+	stmt, err := db.Prepare("INSERT|t|id=?,name=?,nullf=?,notnullf=?")
+	if err != nil {
+		t.Fatalf("prepare: %v", err)
+	}
+	defer stmt.Close()
+	if _, err := stmt.Exec(3, "chris", spec.rows[2].nullParam, spec.rows[2].notNullParam); err != nil {
+		t.Errorf("exec insert chris: %v", err)
+	}
+	if _, err := stmt.Exec(4, "dave", spec.rows[3].nullParam, spec.rows[3].notNullParam); err != nil {
+		t.Errorf("exec insert dave: %v", err)
+	}
+	if _, err := stmt.Exec(5, "eleanor", spec.rows[4].nullParam, spec.rows[4].notNullParam); err != nil {
+		t.Errorf("exec insert eleanor: %v", err)
+	}
+
+	// Can't put null val into non-null col
+	if _, err := stmt.Exec(6, "bob", spec.rows[5].nullParam, spec.rows[5].notNullParam); err == nil {
+		t.Errorf("expected error inserting nil val with prepared statement Exec")
+	}
+
+	_, err = db.Exec("INSERT|t|id=?,name=?,nullf=?", 999, nil, nil)
+	if err == nil {
+		// TODO: this test fails, but it's just because
+		// fakeConn implements the optional Execer interface,
+		// so arguably this is the correct behavior. But
+		// maybe I should flesh out the fakeConn.Exec
+		// implementation so this properly fails.
+		// t.Errorf("expected error inserting nil name with Exec")
+	}
+
+	paramtype := reflect.TypeOf(spec.rows[0].nullParam)
+	bindVal := reflect.New(paramtype).Interface()
+
+	for i := 0; i < 5; i++ {
+		id := i + 1
+		if err := db.QueryRow("SELECT|t|nullf|id=?", id).Scan(bindVal); err != nil {
+			t.Errorf("id=%d Scan: %v", id, err)
+		}
+		bindValDeref := reflect.ValueOf(bindVal).Elem().Interface()
+		if !reflect.DeepEqual(bindValDeref, spec.rows[i].scanNullVal) {
+			t.Errorf("id=%d got %#v, want %#v", id, bindValDeref, spec.rows[i].scanNullVal)
+		}
+	}
+}
+
+// golang.org/issue/4859
+func TestQueryRowNilScanDest(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	var name *string // nil pointer
+	err := db.QueryRow("SELECT|people|name|").Scan(name)
+	want := `sql: Scan error on column index 0, name "name": destination pointer is nil`
+	if err == nil || err.Error() != want {
+		t.Errorf("error = %q; want %q", err.Error(), want)
+	}
+}
+
+func TestIssue4902(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	driver := db.Driver().(*fakeDriver)
+	opens0 := driver.openCount
+
+	var stmt *Stmt
+	var err error
+	for i := 0; i < 10; i++ {
+		stmt, err = db.Prepare("SELECT|people|name|")
+		if err != nil {
+			t.Fatal(err)
+		}
+		err = stmt.Close()
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	opens := driver.openCount - opens0
+	if opens > 1 {
+		t.Errorf("opens = %d; want <= 1", opens)
+		t.Logf("db = %#v", db)
+		t.Logf("driver = %#v", driver)
+		t.Logf("stmt = %#v", stmt)
+	}
+}
+
+// Issue 3857
+// This used to deadlock.
+func TestSimultaneousQueries(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer tx.Rollback()
+
+	r1, err := tx.Query("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer r1.Close()
+
+	r2, err := tx.Query("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer r2.Close()
+}
+
+func TestMaxIdleConns(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	tx.Commit()
+	if got := len(db.freeConn); got != 1 {
+		t.Errorf("freeConns = %d; want 1", got)
+	}
+
+	db.SetMaxIdleConns(0)
+
+	if got := len(db.freeConn); got != 0 {
+		t.Errorf("freeConns after set to zero = %d; want 0", got)
+	}
+
+	tx, err = db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	tx.Commit()
+	if got := len(db.freeConn); got != 0 {
+		t.Errorf("freeConns = %d; want 0", got)
+	}
+}
+
+func TestMaxOpenConns(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
+	defer setHookpostCloseConn(nil)
+	setHookpostCloseConn(func(_ *fakeConn, err error) {
+		if err != nil {
+			t.Errorf("Error closing fakeConn: %v", err)
+		}
+	})
+
+	db := newTestDB(t, "magicquery")
+	defer closeDB(t, db)
+
+	driver := db.Driver().(*fakeDriver)
+
+	// Force the number of open connections to 0 so we can get an accurate
+	// count for the test
+	db.clearAllConns(t)
+
+	driver.mu.Lock()
+	opens0 := driver.openCount
+	closes0 := driver.closeCount
+	driver.mu.Unlock()
+
+	db.SetMaxIdleConns(10)
+	db.SetMaxOpenConns(10)
+
+	stmt, err := db.Prepare("SELECT|magicquery|op|op=?,millis=?")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Start 50 parallel slow queries.
+	const (
+		nquery      = 50
+		sleepMillis = 25
+		nbatch      = 2
+	)
+	var wg sync.WaitGroup
+	for batch := 0; batch < nbatch; batch++ {
+		for i := 0; i < nquery; i++ {
+			wg.Add(1)
+			go func() {
+				defer wg.Done()
+				var op string
+				if err := stmt.QueryRow("sleep", sleepMillis).Scan(&op); err != nil && err != ErrNoRows {
+					t.Error(err)
+				}
+			}()
+		}
+		// Wait for the batch of queries above to finish before starting the next round.
+		wg.Wait()
+	}
+
+	if g, w := db.numFreeConns(), 10; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPoll(t, 20); n > 20 {
+		t.Errorf("number of dependencies = %d; expected <= 20", n)
+		db.dumpDeps(t)
+	}
+
+	driver.mu.Lock()
+	opens := driver.openCount - opens0
+	closes := driver.closeCount - closes0
+	driver.mu.Unlock()
+
+	if opens > 10 {
+		t.Logf("open calls = %d", opens)
+		t.Logf("close calls = %d", closes)
+		t.Errorf("db connections opened = %d; want <= 10", opens)
+		db.dumpDeps(t)
+	}
+
+	if err := stmt.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	if g, w := db.numFreeConns(), 10; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPoll(t, 10); n > 10 {
+		t.Errorf("number of dependencies = %d; expected <= 10", n)
+		db.dumpDeps(t)
+	}
+
+	db.SetMaxOpenConns(5)
+
+	if g, w := db.numFreeConns(), 5; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPoll(t, 5); n > 5 {
+		t.Errorf("number of dependencies = %d; expected 0", n)
+		db.dumpDeps(t)
+	}
+
+	db.SetMaxOpenConns(0)
+
+	if g, w := db.numFreeConns(), 5; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPoll(t, 5); n > 5 {
+		t.Errorf("number of dependencies = %d; expected 0", n)
+		db.dumpDeps(t)
+	}
+
+	db.clearAllConns(t)
+}
+
+// Issue 9453: tests that SetMaxOpenConns can be lowered at runtime
+// and affects the subsequent release of connections.
+func TestMaxOpenConnsOnBusy(t *testing.T) {
+	defer setHookpostCloseConn(nil)
+	setHookpostCloseConn(func(_ *fakeConn, err error) {
+		if err != nil {
+			t.Errorf("Error closing fakeConn: %v", err)
+		}
+	})
+
+	db := newTestDB(t, "magicquery")
+	defer closeDB(t, db)
+
+	db.SetMaxOpenConns(3)
+
+	ctx := context.Background()
+
+	conn0, err := db.conn(ctx, cachedOrNewConn)
+	if err != nil {
+		t.Fatalf("db open conn fail: %v", err)
+	}
+
+	conn1, err := db.conn(ctx, cachedOrNewConn)
+	if err != nil {
+		t.Fatalf("db open conn fail: %v", err)
+	}
+
+	conn2, err := db.conn(ctx, cachedOrNewConn)
+	if err != nil {
+		t.Fatalf("db open conn fail: %v", err)
+	}
+
+	if g, w := db.numOpen, 3; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	db.SetMaxOpenConns(2)
+	if g, w := db.numOpen, 3; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	conn0.releaseConn(nil)
+	conn1.releaseConn(nil)
+	if g, w := db.numOpen, 2; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	conn2.releaseConn(nil)
+	if g, w := db.numOpen, 2; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+}
+
+// Issue 10886: tests that all connection attempts return when more than
+// DB.maxOpen connections are in flight and the first DB.maxOpen fail.
+func TestPendingConnsAfterErr(t *testing.T) {
+	const (
+		maxOpen = 2
+		tryOpen = maxOpen*2 + 2
+	)
+
+	// No queries will be run.
+	db, err := Open("test", fakeDBName)
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	defer closeDB(t, db)
+	defer func() {
+		for k, v := range db.lastPut {
+			t.Logf("%p: %v", k, v)
+		}
+	}()
+
+	db.SetMaxOpenConns(maxOpen)
+	db.SetMaxIdleConns(0)
+
+	errOffline := errors.New("db offline")
+
+	defer func() { setHookOpenErr(nil) }()
+
+	errs := make(chan error, tryOpen)
+
+	var opening sync.WaitGroup
+	opening.Add(tryOpen)
+
+	setHookOpenErr(func() error {
+		// Wait for all connections to enqueue.
+		opening.Wait()
+		return errOffline
+	})
+
+	for i := 0; i < tryOpen; i++ {
+		go func() {
+			opening.Done() // signal one connection is in flight
+			_, err := db.Exec("will never run")
+			errs <- err
+		}()
+	}
+
+	opening.Wait() // wait for all workers to begin running
+
+	const timeout = 5 * time.Second
+	to := time.NewTimer(timeout)
+	defer to.Stop()
+
+	// check that all connections fail without deadlock
+	for i := 0; i < tryOpen; i++ {
+		select {
+		case err := <-errs:
+			if got, want := err, errOffline; got != want {
+				t.Errorf("unexpected err: got %v, want %v", got, want)
+			}
+		case <-to.C:
+			t.Fatalf("orphaned connection request(s), still waiting after %v", timeout)
+		}
+	}
+
+	// Wait a reasonable time for the database to close all connections.
+	tick := time.NewTicker(3 * time.Millisecond)
+	defer tick.Stop()
+	for {
+		select {
+		case <-tick.C:
+			db.mu.Lock()
+			if db.numOpen == 0 {
+				db.mu.Unlock()
+				return
+			}
+			db.mu.Unlock()
+		case <-to.C:
+			// Closing the database will check for numOpen and fail the test.
+			return
+		}
+	}
+}
+
+func TestSingleOpenConn(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	db.SetMaxOpenConns(1)
+
+	rows, err := db.Query("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = rows.Close(); err != nil {
+		t.Fatal(err)
+	}
+	// shouldn't deadlock
+	rows, err = db.Query("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = rows.Close(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestStats(t *testing.T) {
+	db := newTestDB(t, "people")
+	stats := db.Stats()
+	if got := stats.OpenConnections; got != 1 {
+		t.Errorf("stats.OpenConnections = %d; want 1", got)
+	}
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	tx.Commit()
+
+	closeDB(t, db)
+	stats = db.Stats()
+	if got := stats.OpenConnections; got != 0 {
+		t.Errorf("stats.OpenConnections = %d; want 0", got)
+	}
+}
+
+func TestConnMaxLifetime(t *testing.T) {
+	t0 := time.Unix(1000000, 0)
+	offset := time.Duration(0)
+
+	nowFunc = func() time.Time { return t0.Add(offset) }
+	defer func() { nowFunc = time.Now }()
+
+	db := newTestDB(t, "magicquery")
+	defer closeDB(t, db)
+
+	driver := db.Driver().(*fakeDriver)
+
+	// Force the number of open connections to 0 so we can get an accurate
+	// count for the test
+	db.clearAllConns(t)
+
+	driver.mu.Lock()
+	opens0 := driver.openCount
+	closes0 := driver.closeCount
+	driver.mu.Unlock()
+
+	db.SetMaxIdleConns(10)
+	db.SetMaxOpenConns(10)
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	offset = time.Second
+	tx2, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tx.Commit()
+	tx2.Commit()
+
+	driver.mu.Lock()
+	opens := driver.openCount - opens0
+	closes := driver.closeCount - closes0
+	driver.mu.Unlock()
+
+	if opens != 2 {
+		t.Errorf("opens = %d; want 2", opens)
+	}
+	if closes != 0 {
+		t.Errorf("closes = %d; want 0", closes)
+	}
+	if g, w := db.numFreeConns(), 2; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	// Expire first conn
+	offset = 11 * time.Second
+	db.SetConnMaxLifetime(10 * time.Second)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tx, err = db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	tx2, err = db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	tx.Commit()
+	tx2.Commit()
+
+	// Give connectionCleaner chance to run.
+	waitCondition(t, func() bool {
+		driver.mu.Lock()
+		opens = driver.openCount - opens0
+		closes = driver.closeCount - closes0
+		driver.mu.Unlock()
+
+		return closes == 1
+	})
+
+	if opens != 3 {
+		t.Errorf("opens = %d; want 3", opens)
+	}
+	if closes != 1 {
+		t.Errorf("closes = %d; want 1", closes)
+	}
+
+	if s := db.Stats(); s.MaxLifetimeClosed != 1 {
+		t.Errorf("MaxLifetimeClosed = %d; want 1 %#v", s.MaxLifetimeClosed, s)
+	}
+}
+
+// golang.org/issue/5323
+func TestStmtCloseDeps(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
+	defer setHookpostCloseConn(nil)
+	setHookpostCloseConn(func(_ *fakeConn, err error) {
+		if err != nil {
+			t.Errorf("Error closing fakeConn: %v", err)
+		}
+	})
+
+	db := newTestDB(t, "magicquery")
+	defer closeDB(t, db)
+
+	driver := db.Driver().(*fakeDriver)
+
+	driver.mu.Lock()
+	opens0 := driver.openCount
+	closes0 := driver.closeCount
+	driver.mu.Unlock()
+	openDelta0 := opens0 - closes0
+
+	stmt, err := db.Prepare("SELECT|magicquery|op|op=?,millis=?")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Start 50 parallel slow queries.
+	const (
+		nquery      = 50
+		sleepMillis = 25
+		nbatch      = 2
+	)
+	var wg sync.WaitGroup
+	for batch := 0; batch < nbatch; batch++ {
+		for i := 0; i < nquery; i++ {
+			wg.Add(1)
+			go func() {
+				defer wg.Done()
+				var op string
+				if err := stmt.QueryRow("sleep", sleepMillis).Scan(&op); err != nil && err != ErrNoRows {
+					t.Error(err)
+				}
+			}()
+		}
+		// Wait for the batch of queries above to finish before starting the next round.
+		wg.Wait()
+	}
+
+	if g, w := db.numFreeConns(), 2; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPoll(t, 4); n > 4 {
+		t.Errorf("number of dependencies = %d; expected <= 4", n)
+		db.dumpDeps(t)
+	}
+
+	driver.mu.Lock()
+	opens := driver.openCount - opens0
+	closes := driver.closeCount - closes0
+	openDelta := (driver.openCount - driver.closeCount) - openDelta0
+	driver.mu.Unlock()
+
+	if openDelta > 2 {
+		t.Logf("open calls = %d", opens)
+		t.Logf("close calls = %d", closes)
+		t.Logf("open delta = %d", openDelta)
+		t.Errorf("db connections opened = %d; want <= 2", openDelta)
+		db.dumpDeps(t)
+	}
+
+	if !waitCondition(t, func() bool {
+		return len(stmt.css) <= nquery
+	}) {
+		t.Errorf("len(stmt.css) = %d; want <= %d", len(stmt.css), nquery)
+	}
+
+	if err := stmt.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	if g, w := db.numFreeConns(), 2; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPoll(t, 2); n > 2 {
+		t.Errorf("number of dependencies = %d; expected <= 2", n)
+		db.dumpDeps(t)
+	}
+
+	db.clearAllConns(t)
+}
+
+// golang.org/issue/5046
+func TestCloseConnBeforeStmts(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	defer setHookpostCloseConn(nil)
+	setHookpostCloseConn(func(_ *fakeConn, err error) {
+		if err != nil {
+			t.Errorf("Error closing fakeConn: %v; from %s", err, stack())
+			db.dumpDeps(t)
+			t.Errorf("DB = %#v", db)
+		}
+	})
+
+	stmt, err := db.Prepare("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(db.freeConn) != 1 {
+		t.Fatalf("expected 1 freeConn; got %d", len(db.freeConn))
+	}
+	dc := db.freeConn[0]
+	if dc.closed {
+		t.Errorf("conn shouldn't be closed")
+	}
+
+	if n := len(dc.openStmt); n != 1 {
+		t.Errorf("driverConn num openStmt = %d; want 1", n)
+	}
+	err = db.Close()
+	if err != nil {
+		t.Errorf("db Close = %v", err)
+	}
+	if !dc.closed {
+		t.Errorf("after db.Close, driverConn should be closed")
+	}
+	if n := len(dc.openStmt); n != 0 {
+		t.Errorf("driverConn num openStmt = %d; want 0", n)
+	}
+
+	err = stmt.Close()
+	if err != nil {
+		t.Errorf("Stmt close = %v", err)
+	}
+
+	if !dc.closed {
+		t.Errorf("conn should be closed")
+	}
+	if dc.ci != nil {
+		t.Errorf("after Stmt Close, driverConn's Conn interface should be nil")
+	}
+}
+
+// golang.org/issue/5283: don't release the Rows' connection in Close
+// before calling Stmt.Close.
+func TestRowsCloseOrder(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	db.SetMaxIdleConns(0)
+	setStrictFakeConnClose(t)
+	defer setStrictFakeConnClose(nil)
+
+	rows, err := db.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = rows.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestRowsImplicitClose(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	rows, err := db.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	want, fail := 2, errors.New("fail")
+	r := rows.rowsi.(*rowsCursor)
+	r.errPos, r.err = want, fail
+
+	got := 0
+	for rows.Next() {
+		got++
+	}
+	if got != want {
+		t.Errorf("got %d rows, want %d", got, want)
+	}
+	if err := rows.Err(); err != fail {
+		t.Errorf("got error %v, want %v", err, fail)
+	}
+	if !r.closed {
+		t.Errorf("r.closed is false, want true")
+	}
+}
+
+func TestRowsCloseError(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer db.Close()
+	rows, err := db.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+	type row struct {
+		age  int
+		name string
+	}
+	got := []row{}
+
+	rc, ok := rows.rowsi.(*rowsCursor)
+	if !ok {
+		t.Fatal("not using *rowsCursor")
+	}
+	rc.closeErr = errors.New("rowsCursor: failed to close")
+
+	for rows.Next() {
+		var r row
+		err = rows.Scan(&r.age, &r.name)
+		if err != nil {
+			t.Fatalf("Scan: %v", err)
+		}
+		got = append(got, r)
+	}
+	err = rows.Err()
+	if err != rc.closeErr {
+		t.Fatalf("unexpected err: got %v, want %v", err, rc.closeErr)
+	}
+}
+
+func TestStmtCloseOrder(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	db.SetMaxIdleConns(0)
+	setStrictFakeConnClose(t)
+	defer setStrictFakeConnClose(nil)
+
+	_, err := db.Query("SELECT|non_existent|name|")
+	if err == nil {
+		t.Fatal("Querying non-existent table should fail")
+	}
+}
+
+// Test cases where there's more than maxBadConnRetries bad connections in the
+// pool (issue 8834)
+func TestManyErrBadConn(t *testing.T) {
+	manyErrBadConnSetup := func(first ...func(db *DB)) *DB {
+		db := newTestDB(t, "people")
+
+		for _, f := range first {
+			f(db)
+		}
+
+		nconn := maxBadConnRetries + 1
+		db.SetMaxIdleConns(nconn)
+		db.SetMaxOpenConns(nconn)
+		// open enough connections
+		func() {
+			for i := 0; i < nconn; i++ {
+				rows, err := db.Query("SELECT|people|age,name|")
+				if err != nil {
+					t.Fatal(err)
+				}
+				defer rows.Close()
+			}
+		}()
+
+		db.mu.Lock()
+		defer db.mu.Unlock()
+		if db.numOpen != nconn {
+			t.Fatalf("unexpected numOpen %d (was expecting %d)", db.numOpen, nconn)
+		} else if len(db.freeConn) != nconn {
+			t.Fatalf("unexpected len(db.freeConn) %d (was expecting %d)", len(db.freeConn), nconn)
+		}
+		for _, conn := range db.freeConn {
+			conn.Lock()
+			conn.ci.(*fakeConn).stickyBad = true
+			conn.Unlock()
+		}
+		return db
+	}
+
+	// Query
+	db := manyErrBadConnSetup()
+	defer closeDB(t, db)
+	rows, err := db.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = rows.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Exec
+	db = manyErrBadConnSetup()
+	defer closeDB(t, db)
+	_, err = db.Exec("INSERT|people|name=Julia,age=19")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Begin
+	db = manyErrBadConnSetup()
+	defer closeDB(t, db)
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = tx.Rollback(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Prepare
+	db = manyErrBadConnSetup()
+	defer closeDB(t, db)
+	stmt, err := db.Prepare("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = stmt.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Stmt.Exec
+	db = manyErrBadConnSetup(func(db *DB) {
+		stmt, err = db.Prepare("INSERT|people|name=Julia,age=19")
+		if err != nil {
+			t.Fatal(err)
+		}
+	})
+	defer closeDB(t, db)
+	_, err = stmt.Exec()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = stmt.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Stmt.Query
+	db = manyErrBadConnSetup(func(db *DB) {
+		stmt, err = db.Prepare("SELECT|people|age,name|")
+		if err != nil {
+			t.Fatal(err)
+		}
+	})
+	defer closeDB(t, db)
+	rows, err = stmt.Query()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = rows.Close(); err != nil {
+		t.Fatal(err)
+	}
+	if err = stmt.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Conn
+	db = manyErrBadConnSetup()
+	defer closeDB(t, db)
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	conn, err := db.Conn(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	conn.dc.ci.(*fakeConn).skipDirtySession = true
+	err = conn.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Ping
+	db = manyErrBadConnSetup()
+	defer closeDB(t, db)
+	err = db.PingContext(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+// Issue 34775: Ensure that a Tx cannot commit after a rollback.
+func TestTxCannotCommitAfterRollback(t *testing.T) {
+	db := newTestDB(t, "tx_status")
+	defer closeDB(t, db)
+
+	// First check query reporting is correct.
+	var txStatus string
+	err := db.QueryRow("SELECT|tx_status|tx_status|").Scan(&txStatus)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if g, w := txStatus, "autocommit"; g != w {
+		t.Fatalf("tx_status=%q, wanted %q", g, w)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	tx, err := db.BeginTx(ctx, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Ignore dirty session for this test.
+	// A failing test should trigger the dirty session flag as well,
+	// but that isn't exactly what this should test for.
+	tx.txi.(*fakeTx).c.skipDirtySession = true
+
+	defer tx.Rollback()
+
+	err = tx.QueryRow("SELECT|tx_status|tx_status|").Scan(&txStatus)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if g, w := txStatus, "transaction"; g != w {
+		t.Fatalf("tx_status=%q, wanted %q", g, w)
+	}
+
+	// 1. Begin a transaction.
+	// 2. (A) Start a query, (B) begin Tx rollback through a ctx cancel.
+	// 3. Check if 2.A has committed in Tx (pass) or outside of Tx (fail).
+	sendQuery := make(chan struct{})
+	// The Tx status is returned through the row results, ensure
+	// that the rows results are not canceled.
+	bypassRowsAwaitDone = true
+	hookTxGrabConn = func() {
+		cancel()
+		<-sendQuery
+	}
+	rollbackHook = func() {
+		close(sendQuery)
+	}
+	defer func() {
+		hookTxGrabConn = nil
+		rollbackHook = nil
+		bypassRowsAwaitDone = false
+	}()
+
+	err = tx.QueryRow("SELECT|tx_status|tx_status|").Scan(&txStatus)
+	if err != nil {
+		// A failure here would be expected if skipDirtySession was not set to true above.
+		t.Fatal(err)
+	}
+	if g, w := txStatus, "transaction"; g != w {
+		t.Fatalf("tx_status=%q, wanted %q", g, w)
+	}
+}
+
+// Issue 40985 transaction statement deadlock while context cancel.
+func TestTxStmtDeadlock(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	tx, err := db.BeginTx(ctx, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	stmt, err := tx.Prepare("SELECT|people|name,age|age=?")
+	if err != nil {
+		t.Fatal(err)
+	}
+	cancel()
+	// Run number of stmt queries to reproduce deadlock from context cancel
+	for i := 0; i < 1e3; i++ {
+		// Encounter any close related errors (e.g. ErrTxDone, stmt is closed)
+		// is expected due to context cancel.
+		_, err = stmt.Query(1)
+		if err != nil {
+			break
+		}
+	}
+	_ = tx.Rollback()
+}
+
+// Issue32530 encounters an issue where a connection may
+// expire right after it comes out of a used connection pool
+// even when a new connection is requested.
+func TestConnExpiresFreshOutOfPool(t *testing.T) {
+	execCases := []struct {
+		expired  bool
+		badReset bool
+	}{
+		{false, false},
+		{true, false},
+		{false, true},
+	}
+
+	t0 := time.Unix(1000000, 0)
+	offset := time.Duration(0)
+	offsetMu := sync.RWMutex{}
+
+	nowFunc = func() time.Time {
+		offsetMu.RLock()
+		defer offsetMu.RUnlock()
+		return t0.Add(offset)
+	}
+	defer func() { nowFunc = time.Now }()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	db := newTestDB(t, "magicquery")
+	defer closeDB(t, db)
+
+	db.SetMaxOpenConns(1)
+
+	for _, ec := range execCases {
+		ec := ec
+		name := fmt.Sprintf("expired=%t,badReset=%t", ec.expired, ec.badReset)
+		t.Run(name, func(t *testing.T) {
+			db.clearAllConns(t)
+
+			db.SetMaxIdleConns(1)
+			db.SetConnMaxLifetime(10 * time.Second)
+
+			conn, err := db.conn(ctx, alwaysNewConn)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			afterPutConn := make(chan struct{})
+			waitingForConn := make(chan struct{})
+
+			go func() {
+				defer close(afterPutConn)
+
+				conn, err := db.conn(ctx, alwaysNewConn)
+				if err == nil {
+					db.putConn(conn, err, false)
+				} else {
+					t.Errorf("db.conn: %v", err)
+				}
+			}()
+			go func() {
+				defer close(waitingForConn)
+
+				for {
+					if t.Failed() {
+						return
+					}
+					db.mu.Lock()
+					ct := len(db.connRequests)
+					db.mu.Unlock()
+					if ct > 0 {
+						return
+					}
+					time.Sleep(pollDuration)
+				}
+			}()
+
+			<-waitingForConn
+
+			if t.Failed() {
+				return
+			}
+
+			offsetMu.Lock()
+			if ec.expired {
+				offset = 11 * time.Second
+			} else {
+				offset = time.Duration(0)
+			}
+			offsetMu.Unlock()
+
+			conn.ci.(*fakeConn).stickyBad = ec.badReset
+
+			db.putConn(conn, err, true)
+
+			<-afterPutConn
+		})
+	}
+}
+
+// TestIssue20575 ensures the Rows from query does not block
+// closing a transaction. Ensure Rows is closed while closing a transaction.
+func TestIssue20575(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+	_, err = tx.QueryContext(ctx, "SELECT|people|age,name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Do not close Rows from QueryContext.
+	err = tx.Rollback()
+	if err != nil {
+		t.Fatal(err)
+	}
+	select {
+	default:
+	case <-ctx.Done():
+		t.Fatal("timeout: failed to rollback query without closing rows:", ctx.Err())
+	}
+}
+
+// TestIssue20622 tests closing the transaction before rows is closed, requires
+// the race detector to fail.
+func TestIssue20622(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	tx, err := db.BeginTx(ctx, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rows, err := tx.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	count := 0
+	for rows.Next() {
+		count++
+		var age int
+		var name string
+		if err := rows.Scan(&age, &name); err != nil {
+			t.Fatal("scan failed", err)
+		}
+
+		if count == 1 {
+			cancel()
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+	rows.Close()
+	tx.Commit()
+}
+
+// golang.org/issue/5718
+func TestErrBadConnReconnect(t *testing.T) {
+	db := newTestDB(t, "foo")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+
+	simulateBadConn := func(name string, hook *func() bool, op func() error) {
+		broken, retried := false, false
+		numOpen := db.numOpen
+
+		// simulate a broken connection on the first try
+		*hook = func() bool {
+			if !broken {
+				broken = true
+				return true
+			}
+			retried = true
+			return false
+		}
+
+		if err := op(); err != nil {
+			t.Errorf(name+": %v", err)
+			return
+		}
+
+		if !broken || !retried {
+			t.Error(name + ": Failed to simulate broken connection")
+		}
+		*hook = nil
+
+		if numOpen != db.numOpen {
+			t.Errorf(name+": leaked %d connection(s)!", db.numOpen-numOpen)
+			numOpen = db.numOpen
+		}
+	}
+
+	// db.Exec
+	dbExec := func() error {
+		_, err := db.Exec("INSERT|t1|name=?,age=?,dead=?", "Gordon", 3, true)
+		return err
+	}
+	simulateBadConn("db.Exec prepare", &hookPrepareBadConn, dbExec)
+	simulateBadConn("db.Exec exec", &hookExecBadConn, dbExec)
+
+	// db.Query
+	dbQuery := func() error {
+		rows, err := db.Query("SELECT|t1|age,name|")
+		if err == nil {
+			err = rows.Close()
+		}
+		return err
+	}
+	simulateBadConn("db.Query prepare", &hookPrepareBadConn, dbQuery)
+	simulateBadConn("db.Query query", &hookQueryBadConn, dbQuery)
+
+	// db.Prepare
+	simulateBadConn("db.Prepare", &hookPrepareBadConn, func() error {
+		stmt, err := db.Prepare("INSERT|t1|name=?,age=?,dead=?")
+		if err != nil {
+			return err
+		}
+		stmt.Close()
+		return nil
+	})
+
+	// Provide a way to force a re-prepare of a statement on next execution
+	forcePrepare := func(stmt *Stmt) {
+		stmt.css = nil
+	}
+
+	// stmt.Exec
+	stmt1, err := db.Prepare("INSERT|t1|name=?,age=?,dead=?")
+	if err != nil {
+		t.Fatalf("prepare: %v", err)
+	}
+	defer stmt1.Close()
+	// make sure we must prepare the stmt first
+	forcePrepare(stmt1)
+
+	stmtExec := func() error {
+		_, err := stmt1.Exec("Gopher", 3, false)
+		return err
+	}
+	simulateBadConn("stmt.Exec prepare", &hookPrepareBadConn, stmtExec)
+	simulateBadConn("stmt.Exec exec", &hookExecBadConn, stmtExec)
+
+	// stmt.Query
+	stmt2, err := db.Prepare("SELECT|t1|age,name|")
+	if err != nil {
+		t.Fatalf("prepare: %v", err)
+	}
+	defer stmt2.Close()
+	// make sure we must prepare the stmt first
+	forcePrepare(stmt2)
+
+	stmtQuery := func() error {
+		rows, err := stmt2.Query()
+		if err == nil {
+			err = rows.Close()
+		}
+		return err
+	}
+	simulateBadConn("stmt.Query prepare", &hookPrepareBadConn, stmtQuery)
+	simulateBadConn("stmt.Query exec", &hookQueryBadConn, stmtQuery)
+}
+
+// golang.org/issue/11264
+func TestTxEndBadConn(t *testing.T) {
+	db := newTestDB(t, "foo")
+	defer closeDB(t, db)
+	db.SetMaxIdleConns(0)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	db.SetMaxIdleConns(1)
+
+	simulateBadConn := func(name string, hook *func() bool, op func() error) {
+		broken := false
+		numOpen := db.numOpen
+
+		*hook = func() bool {
+			if !broken {
+				broken = true
+			}
+			return broken
+		}
+
+		if err := op(); !errors.Is(err, driver.ErrBadConn) {
+			t.Errorf(name+": %v", err)
+			return
+		}
+
+		if !broken {
+			t.Error(name + ": Failed to simulate broken connection")
+		}
+		*hook = nil
+
+		if numOpen != db.numOpen {
+			t.Errorf(name+": leaked %d connection(s)!", db.numOpen-numOpen)
+		}
+	}
+
+	// db.Exec
+	dbExec := func(endTx func(tx *Tx) error) func() error {
+		return func() error {
+			tx, err := db.Begin()
+			if err != nil {
+				return err
+			}
+			_, err = tx.Exec("INSERT|t1|name=?,age=?,dead=?", "Gordon", 3, true)
+			if err != nil {
+				return err
+			}
+			return endTx(tx)
+		}
+	}
+	simulateBadConn("db.Tx.Exec commit", &hookCommitBadConn, dbExec((*Tx).Commit))
+	simulateBadConn("db.Tx.Exec rollback", &hookRollbackBadConn, dbExec((*Tx).Rollback))
+
+	// db.Query
+	dbQuery := func(endTx func(tx *Tx) error) func() error {
+		return func() error {
+			tx, err := db.Begin()
+			if err != nil {
+				return err
+			}
+			rows, err := tx.Query("SELECT|t1|age,name|")
+			if err == nil {
+				err = rows.Close()
+			} else {
+				return err
+			}
+			return endTx(tx)
+		}
+	}
+	simulateBadConn("db.Tx.Query commit", &hookCommitBadConn, dbQuery((*Tx).Commit))
+	simulateBadConn("db.Tx.Query rollback", &hookRollbackBadConn, dbQuery((*Tx).Rollback))
+}
+
+type concurrentTest interface {
+	init(t testing.TB, db *DB)
+	finish(t testing.TB)
+	test(t testing.TB) error
+}
+
+type concurrentDBQueryTest struct {
+	db *DB
+}
+
+func (c *concurrentDBQueryTest) init(t testing.TB, db *DB) {
+	c.db = db
+}
+
+func (c *concurrentDBQueryTest) finish(t testing.TB) {
+	c.db = nil
+}
+
+func (c *concurrentDBQueryTest) test(t testing.TB) error {
+	rows, err := c.db.Query("SELECT|people|name|")
+	if err != nil {
+		t.Error(err)
+		return err
+	}
+	var name string
+	for rows.Next() {
+		rows.Scan(&name)
+	}
+	rows.Close()
+	return nil
+}
+
+type concurrentDBExecTest struct {
+	db *DB
+}
+
+func (c *concurrentDBExecTest) init(t testing.TB, db *DB) {
+	c.db = db
+}
+
+func (c *concurrentDBExecTest) finish(t testing.TB) {
+	c.db = nil
+}
+
+func (c *concurrentDBExecTest) test(t testing.TB) error {
+	_, err := c.db.Exec("NOSERT|people|name=Chris,age=?,photo=CPHOTO,bdate=?", 3, chrisBirthday)
+	if err != nil {
+		t.Error(err)
+		return err
+	}
+	return nil
+}
+
+type concurrentStmtQueryTest struct {
+	db   *DB
+	stmt *Stmt
+}
+
+func (c *concurrentStmtQueryTest) init(t testing.TB, db *DB) {
+	c.db = db
+	var err error
+	c.stmt, err = db.Prepare("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func (c *concurrentStmtQueryTest) finish(t testing.TB) {
+	if c.stmt != nil {
+		c.stmt.Close()
+		c.stmt = nil
+	}
+	c.db = nil
+}
+
+func (c *concurrentStmtQueryTest) test(t testing.TB) error {
+	rows, err := c.stmt.Query()
+	if err != nil {
+		t.Errorf("error on query:  %v", err)
+		return err
+	}
+
+	var name string
+	for rows.Next() {
+		rows.Scan(&name)
+	}
+	rows.Close()
+	return nil
+}
+
+type concurrentStmtExecTest struct {
+	db   *DB
+	stmt *Stmt
+}
+
+func (c *concurrentStmtExecTest) init(t testing.TB, db *DB) {
+	c.db = db
+	var err error
+	c.stmt, err = db.Prepare("NOSERT|people|name=Chris,age=?,photo=CPHOTO,bdate=?")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func (c *concurrentStmtExecTest) finish(t testing.TB) {
+	if c.stmt != nil {
+		c.stmt.Close()
+		c.stmt = nil
+	}
+	c.db = nil
+}
+
+func (c *concurrentStmtExecTest) test(t testing.TB) error {
+	_, err := c.stmt.Exec(3, chrisBirthday)
+	if err != nil {
+		t.Errorf("error on exec:  %v", err)
+		return err
+	}
+	return nil
+}
+
+type concurrentTxQueryTest struct {
+	db *DB
+	tx *Tx
+}
+
+func (c *concurrentTxQueryTest) init(t testing.TB, db *DB) {
+	c.db = db
+	var err error
+	c.tx, err = c.db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func (c *concurrentTxQueryTest) finish(t testing.TB) {
+	if c.tx != nil {
+		c.tx.Rollback()
+		c.tx = nil
+	}
+	c.db = nil
+}
+
+func (c *concurrentTxQueryTest) test(t testing.TB) error {
+	rows, err := c.db.Query("SELECT|people|name|")
+	if err != nil {
+		t.Error(err)
+		return err
+	}
+	var name string
+	for rows.Next() {
+		rows.Scan(&name)
+	}
+	rows.Close()
+	return nil
+}
+
+type concurrentTxExecTest struct {
+	db *DB
+	tx *Tx
+}
+
+func (c *concurrentTxExecTest) init(t testing.TB, db *DB) {
+	c.db = db
+	var err error
+	c.tx, err = c.db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func (c *concurrentTxExecTest) finish(t testing.TB) {
+	if c.tx != nil {
+		c.tx.Rollback()
+		c.tx = nil
+	}
+	c.db = nil
+}
+
+func (c *concurrentTxExecTest) test(t testing.TB) error {
+	_, err := c.tx.Exec("NOSERT|people|name=Chris,age=?,photo=CPHOTO,bdate=?", 3, chrisBirthday)
+	if err != nil {
+		t.Error(err)
+		return err
+	}
+	return nil
+}
+
+type concurrentTxStmtQueryTest struct {
+	db   *DB
+	tx   *Tx
+	stmt *Stmt
+}
+
+func (c *concurrentTxStmtQueryTest) init(t testing.TB, db *DB) {
+	c.db = db
+	var err error
+	c.tx, err = c.db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	c.stmt, err = c.tx.Prepare("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func (c *concurrentTxStmtQueryTest) finish(t testing.TB) {
+	if c.stmt != nil {
+		c.stmt.Close()
+		c.stmt = nil
+	}
+	if c.tx != nil {
+		c.tx.Rollback()
+		c.tx = nil
+	}
+	c.db = nil
+}
+
+func (c *concurrentTxStmtQueryTest) test(t testing.TB) error {
+	rows, err := c.stmt.Query()
+	if err != nil {
+		t.Errorf("error on query:  %v", err)
+		return err
+	}
+
+	var name string
+	for rows.Next() {
+		rows.Scan(&name)
+	}
+	rows.Close()
+	return nil
+}
+
+type concurrentTxStmtExecTest struct {
+	db   *DB
+	tx   *Tx
+	stmt *Stmt
+}
+
+func (c *concurrentTxStmtExecTest) init(t testing.TB, db *DB) {
+	c.db = db
+	var err error
+	c.tx, err = c.db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	c.stmt, err = c.tx.Prepare("NOSERT|people|name=Chris,age=?,photo=CPHOTO,bdate=?")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func (c *concurrentTxStmtExecTest) finish(t testing.TB) {
+	if c.stmt != nil {
+		c.stmt.Close()
+		c.stmt = nil
+	}
+	if c.tx != nil {
+		c.tx.Rollback()
+		c.tx = nil
+	}
+	c.db = nil
+}
+
+func (c *concurrentTxStmtExecTest) test(t testing.TB) error {
+	_, err := c.stmt.Exec(3, chrisBirthday)
+	if err != nil {
+		t.Errorf("error on exec:  %v", err)
+		return err
+	}
+	return nil
+}
+
+type concurrentRandomTest struct {
+	tests []concurrentTest
+}
+
+func (c *concurrentRandomTest) init(t testing.TB, db *DB) {
+	c.tests = []concurrentTest{
+		new(concurrentDBQueryTest),
+		new(concurrentDBExecTest),
+		new(concurrentStmtQueryTest),
+		new(concurrentStmtExecTest),
+		new(concurrentTxQueryTest),
+		new(concurrentTxExecTest),
+		new(concurrentTxStmtQueryTest),
+		new(concurrentTxStmtExecTest),
+	}
+	for _, ct := range c.tests {
+		ct.init(t, db)
+	}
+}
+
+func (c *concurrentRandomTest) finish(t testing.TB) {
+	for _, ct := range c.tests {
+		ct.finish(t)
+	}
+}
+
+func (c *concurrentRandomTest) test(t testing.TB) error {
+	ct := c.tests[rand.Intn(len(c.tests))]
+	return ct.test(t)
+}
+
+func doConcurrentTest(t testing.TB, ct concurrentTest) {
+	maxProcs, numReqs := 1, 500
+	if testing.Short() {
+		maxProcs, numReqs = 4, 50
+	}
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(maxProcs))
+
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ct.init(t, db)
+	defer ct.finish(t)
+
+	var wg sync.WaitGroup
+	wg.Add(numReqs)
+
+	reqs := make(chan bool)
+	defer close(reqs)
+
+	for i := 0; i < maxProcs*2; i++ {
+		go func() {
+			for range reqs {
+				err := ct.test(t)
+				if err != nil {
+					wg.Done()
+					continue
+				}
+				wg.Done()
+			}
+		}()
+	}
+
+	for i := 0; i < numReqs; i++ {
+		reqs <- true
+	}
+
+	wg.Wait()
+}
+
+func TestIssue6081(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	drv := db.Driver().(*fakeDriver)
+	drv.mu.Lock()
+	opens0 := drv.openCount
+	closes0 := drv.closeCount
+	drv.mu.Unlock()
+
+	stmt, err := db.Prepare("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	setRowsCloseHook(func(rows *Rows, err *error) {
+		*err = driver.ErrBadConn
+	})
+	defer setRowsCloseHook(nil)
+	for i := 0; i < 10; i++ {
+		rows, err := stmt.Query()
+		if err != nil {
+			t.Fatal(err)
+		}
+		rows.Close()
+	}
+	if n := len(stmt.css); n > 1 {
+		t.Errorf("len(css slice) = %d; want <= 1", n)
+	}
+	stmt.Close()
+	if n := len(stmt.css); n != 0 {
+		t.Errorf("len(css slice) after Close = %d; want 0", n)
+	}
+
+	drv.mu.Lock()
+	opens := drv.openCount - opens0
+	closes := drv.closeCount - closes0
+	drv.mu.Unlock()
+	if opens < 9 {
+		t.Errorf("opens = %d; want >= 9", opens)
+	}
+	if closes < 9 {
+		t.Errorf("closes = %d; want >= 9", closes)
+	}
+}
+
+// TestIssue18429 attempts to stress rolling back the transaction from a
+// context cancel while simultaneously calling Tx.Rollback. Rolling back from a
+// context happens concurrently so tx.rollback and tx.Commit must guard against
+// double entry.
+//
+// In the test, a context is canceled while the query is in process so
+// the internal rollback will run concurrently with the explicitly called
+// Tx.Rollback.
+//
+// The addition of calling rows.Next also tests
+// Issue 21117.
+func TestIssue18429(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ctx := context.Background()
+	sem := make(chan bool, 20)
+	var wg sync.WaitGroup
+
+	const milliWait = 30
+
+	for i := 0; i < 100; i++ {
+		sem <- true
+		wg.Add(1)
+		go func() {
+			defer func() {
+				<-sem
+				wg.Done()
+			}()
+			qwait := (time.Duration(rand.Intn(milliWait)) * time.Millisecond).String()
+
+			ctx, cancel := context.WithTimeout(ctx, time.Duration(rand.Intn(milliWait))*time.Millisecond)
+			defer cancel()
+
+			tx, err := db.BeginTx(ctx, nil)
+			if err != nil {
+				return
+			}
+			// This is expected to give a cancel error most, but not all the time.
+			// Test failure will happen with a panic or other race condition being
+			// reported.
+			rows, _ := tx.QueryContext(ctx, "WAIT|"+qwait+"|SELECT|people|name|")
+			if rows != nil {
+				var name string
+				// Call Next to test Issue 21117 and check for races.
+				for rows.Next() {
+					// Scan the buffer so it is read and checked for races.
+					rows.Scan(&name)
+				}
+				rows.Close()
+			}
+			// This call will race with the context cancel rollback to complete
+			// if the rollback itself isn't guarded.
+			tx.Rollback()
+		}()
+	}
+	wg.Wait()
+}
+
+// TestIssue20160 attempts to test a short context life on a stmt Query.
+func TestIssue20160(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ctx := context.Background()
+	sem := make(chan bool, 20)
+	var wg sync.WaitGroup
+
+	const milliWait = 30
+
+	stmt, err := db.PrepareContext(ctx, "SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stmt.Close()
+
+	for i := 0; i < 100; i++ {
+		sem <- true
+		wg.Add(1)
+		go func() {
+			defer func() {
+				<-sem
+				wg.Done()
+			}()
+			ctx, cancel := context.WithTimeout(ctx, time.Duration(rand.Intn(milliWait))*time.Millisecond)
+			defer cancel()
+
+			// This is expected to give a cancel error most, but not all the time.
+			// Test failure will happen with a panic or other race condition being
+			// reported.
+			rows, _ := stmt.QueryContext(ctx)
+			if rows != nil {
+				rows.Close()
+			}
+		}()
+	}
+	wg.Wait()
+}
+
+// TestIssue18719 closes the context right before use. The sql.driverConn
+// will nil out the ci on close in a lock, but if another process uses it right after
+// it will panic with on the nil ref.
+//
+// See https://golang.org/cl/35550 .
+func TestIssue18719(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	tx, err := db.BeginTx(ctx, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	hookTxGrabConn = func() {
+		cancel()
+
+		// Wait for the context to cancel and tx to rollback.
+		for tx.isDone() == false {
+			time.Sleep(pollDuration)
+		}
+	}
+	defer func() { hookTxGrabConn = nil }()
+
+	// This call will grab the connection and cancel the context
+	// after it has done so. Code after must deal with the canceled state.
+	_, err = tx.QueryContext(ctx, "SELECT|people|name|")
+	if err != nil {
+		t.Fatalf("expected error %v but got %v", nil, err)
+	}
+
+	// Rows may be ignored because it will be closed when the context is canceled.
+
+	// Do not explicitly rollback. The rollback will happen from the
+	// canceled context.
+
+	cancel()
+}
+
+func TestIssue20647(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	conn, err := db.Conn(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	conn.dc.ci.(*fakeConn).skipDirtySession = true
+	defer conn.Close()
+
+	stmt, err := conn.PrepareContext(ctx, "SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stmt.Close()
+
+	rows1, err := stmt.QueryContext(ctx)
+	if err != nil {
+		t.Fatal("rows1", err)
+	}
+	defer rows1.Close()
+
+	rows2, err := stmt.QueryContext(ctx)
+	if err != nil {
+		t.Fatal("rows2", err)
+	}
+	defer rows2.Close()
+
+	if rows1.dc != rows2.dc {
+		t.Fatal("stmt prepared on Conn does not use same connection")
+	}
+}
+
+func TestConcurrency(t *testing.T) {
+	list := []struct {
+		name string
+		ct   concurrentTest
+	}{
+		{"Query", new(concurrentDBQueryTest)},
+		{"Exec", new(concurrentDBExecTest)},
+		{"StmtQuery", new(concurrentStmtQueryTest)},
+		{"StmtExec", new(concurrentStmtExecTest)},
+		{"TxQuery", new(concurrentTxQueryTest)},
+		{"TxExec", new(concurrentTxExecTest)},
+		{"TxStmtQuery", new(concurrentTxStmtQueryTest)},
+		{"TxStmtExec", new(concurrentTxStmtExecTest)},
+		{"Random", new(concurrentRandomTest)},
+	}
+	for _, item := range list {
+		t.Run(item.name, func(t *testing.T) {
+			doConcurrentTest(t, item.ct)
+		})
+	}
+}
+
+func TestConnectionLeak(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	// Start by opening defaultMaxIdleConns
+	rows := make([]*Rows, defaultMaxIdleConns)
+	// We need to SetMaxOpenConns > MaxIdleConns, so the DB can open
+	// a new connection and we can fill the idle queue with the released
+	// connections.
+	db.SetMaxOpenConns(len(rows) + 1)
+	for ii := range rows {
+		r, err := db.Query("SELECT|people|name|")
+		if err != nil {
+			t.Fatal(err)
+		}
+		r.Next()
+		if err := r.Err(); err != nil {
+			t.Fatal(err)
+		}
+		rows[ii] = r
+	}
+	// Now we have defaultMaxIdleConns busy connections. Open
+	// a new one, but wait until the busy connections are released
+	// before returning control to DB.
+	drv := db.Driver().(*fakeDriver)
+	drv.waitCh = make(chan struct{}, 1)
+	drv.waitingCh = make(chan struct{}, 1)
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		r, err := db.Query("SELECT|people|name|")
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		r.Close()
+		wg.Done()
+	}()
+	// Wait until the goroutine we've just created has started waiting.
+	<-drv.waitingCh
+	// Now close the busy connections. This provides a connection for
+	// the blocked goroutine and then fills up the idle queue.
+	for _, v := range rows {
+		v.Close()
+	}
+	// At this point we give the new connection to DB. This connection is
+	// now useless, since the idle queue is full and there are no pending
+	// requests. DB should deal with this situation without leaking the
+	// connection.
+	drv.waitCh <- struct{}{}
+	wg.Wait()
+}
+
+func TestStatsMaxIdleClosedZero(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	db.SetMaxOpenConns(1)
+	db.SetMaxIdleConns(1)
+	db.SetConnMaxLifetime(0)
+
+	preMaxIdleClosed := db.Stats().MaxIdleClosed
+
+	for i := 0; i < 10; i++ {
+		rows, err := db.Query("SELECT|people|name|")
+		if err != nil {
+			t.Fatal(err)
+		}
+		rows.Close()
+	}
+
+	st := db.Stats()
+	maxIdleClosed := st.MaxIdleClosed - preMaxIdleClosed
+	t.Logf("MaxIdleClosed: %d", maxIdleClosed)
+	if maxIdleClosed != 0 {
+		t.Fatal("expected 0 max idle closed conns, got: ", maxIdleClosed)
+	}
+}
+
+func TestStatsMaxIdleClosedTen(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	db.SetMaxOpenConns(1)
+	db.SetMaxIdleConns(0)
+	db.SetConnMaxLifetime(0)
+
+	preMaxIdleClosed := db.Stats().MaxIdleClosed
+
+	for i := 0; i < 10; i++ {
+		rows, err := db.Query("SELECT|people|name|")
+		if err != nil {
+			t.Fatal(err)
+		}
+		rows.Close()
+	}
+
+	st := db.Stats()
+	maxIdleClosed := st.MaxIdleClosed - preMaxIdleClosed
+	t.Logf("MaxIdleClosed: %d", maxIdleClosed)
+	if maxIdleClosed != 10 {
+		t.Fatal("expected 0 max idle closed conns, got: ", maxIdleClosed)
+	}
+}
+
+// testUseConns uses count concurrent connections with 1 nanosecond apart.
+// Returns the returnedAt time of the final connection.
+func testUseConns(t *testing.T, count int, tm time.Time, db *DB) time.Time {
+	conns := make([]*Conn, count)
+	ctx := context.Background()
+	for i := range conns {
+		tm = tm.Add(time.Nanosecond)
+		nowFunc = func() time.Time {
+			return tm
+		}
+		c, err := db.Conn(ctx)
+		if err != nil {
+			t.Error(err)
+		}
+		conns[i] = c
+	}
+
+	for i := len(conns) - 1; i >= 0; i-- {
+		tm = tm.Add(time.Nanosecond)
+		nowFunc = func() time.Time {
+			return tm
+		}
+		if err := conns[i].Close(); err != nil {
+			t.Error(err)
+		}
+	}
+
+	return tm
+}
+
+func TestMaxIdleTime(t *testing.T) {
+	usedConns := 5
+	reusedConns := 2
+	list := []struct {
+		wantMaxIdleTime   time.Duration
+		wantMaxLifetime   time.Duration
+		wantNextCheck     time.Duration
+		wantIdleClosed    int64
+		wantMaxIdleClosed int64
+		timeOffset        time.Duration
+		secondTimeOffset  time.Duration
+	}{
+		{
+			time.Millisecond,
+			0,
+			time.Millisecond - time.Nanosecond,
+			int64(usedConns - reusedConns),
+			int64(usedConns - reusedConns),
+			10 * time.Millisecond,
+			0,
+		},
+		{
+			// Want to close some connections via max idle time and one by max lifetime.
+			time.Millisecond,
+			// nowFunc() - MaxLifetime should be 1 * time.Nanosecond in connectionCleanerRunLocked.
+			// This guarantees that first opened connection is to be closed.
+			// Thus it is timeOffset + secondTimeOffset + 3 (+2 for Close while reusing conns and +1 for Conn).
+			10*time.Millisecond + 100*time.Nanosecond + 3*time.Nanosecond,
+			time.Nanosecond,
+			// Closed all not reused connections and extra one by max lifetime.
+			int64(usedConns - reusedConns + 1),
+			int64(usedConns - reusedConns),
+			10 * time.Millisecond,
+			// Add second offset because otherwise connections are expired via max lifetime in Close.
+			100 * time.Nanosecond,
+		},
+		{
+			time.Hour,
+			0,
+			time.Second,
+			0,
+			0,
+			10 * time.Millisecond,
+			0},
+	}
+	baseTime := time.Unix(0, 0)
+	defer func() {
+		nowFunc = time.Now
+	}()
+	for _, item := range list {
+		nowFunc = func() time.Time {
+			return baseTime
+		}
+		t.Run(fmt.Sprintf("%v", item.wantMaxIdleTime), func(t *testing.T) {
+			db := newTestDB(t, "people")
+			defer closeDB(t, db)
+
+			db.SetMaxOpenConns(usedConns)
+			db.SetMaxIdleConns(usedConns)
+			db.SetConnMaxIdleTime(item.wantMaxIdleTime)
+			db.SetConnMaxLifetime(item.wantMaxLifetime)
+
+			preMaxIdleClosed := db.Stats().MaxIdleTimeClosed
+
+			// Busy usedConns.
+			testUseConns(t, usedConns, baseTime, db)
+
+			tm := baseTime.Add(item.timeOffset)
+
+			// Reuse connections which should never be considered idle
+			// and exercises the sorting for issue 39471.
+			tm = testUseConns(t, reusedConns, tm, db)
+
+			tm = tm.Add(item.secondTimeOffset)
+			nowFunc = func() time.Time {
+				return tm
+			}
+
+			db.mu.Lock()
+			nc, closing := db.connectionCleanerRunLocked(time.Second)
+			if nc != item.wantNextCheck {
+				t.Errorf("got %v; want %v next check duration", nc, item.wantNextCheck)
+			}
+
+			// Validate freeConn order.
+			var last time.Time
+			for _, c := range db.freeConn {
+				if last.After(c.returnedAt) {
+					t.Error("freeConn is not ordered by returnedAt")
+					break
+				}
+				last = c.returnedAt
+			}
+
+			db.mu.Unlock()
+			for _, c := range closing {
+				c.Close()
+			}
+			if g, w := int64(len(closing)), item.wantIdleClosed; g != w {
+				t.Errorf("got: %d; want %d closed conns", g, w)
+			}
+
+			st := db.Stats()
+			maxIdleClosed := st.MaxIdleTimeClosed - preMaxIdleClosed
+			if g, w := maxIdleClosed, item.wantMaxIdleClosed; g != w {
+				t.Errorf("got: %d; want %d max idle closed conns", g, w)
+			}
+		})
+	}
+}
+
+type nvcDriver struct {
+	fakeDriver
+	skipNamedValueCheck bool
+}
+
+func (d *nvcDriver) Open(dsn string) (driver.Conn, error) {
+	c, err := d.fakeDriver.Open(dsn)
+	fc := c.(*fakeConn)
+	fc.db.allowAny = true
+	return &nvcConn{fc, d.skipNamedValueCheck}, err
+}
+
+type nvcConn struct {
+	*fakeConn
+	skipNamedValueCheck bool
+}
+
+type decimalInt struct {
+	value int
+}
+
+type doNotInclude struct{}
+
+var _ driver.NamedValueChecker = &nvcConn{}
+
+func (c *nvcConn) CheckNamedValue(nv *driver.NamedValue) error {
+	if c.skipNamedValueCheck {
+		return driver.ErrSkip
+	}
+	switch v := nv.Value.(type) {
+	default:
+		return driver.ErrSkip
+	case Out:
+		switch ov := v.Dest.(type) {
+		default:
+			return errors.New("unknown NameValueCheck OUTPUT type")
+		case *string:
+			*ov = "from-server"
+			nv.Value = "OUT:*string"
+		}
+		return nil
+	case decimalInt, []int64:
+		return nil
+	case doNotInclude:
+		return driver.ErrRemoveArgument
+	}
+}
+
+func TestNamedValueChecker(t *testing.T) {
+	Register("NamedValueCheck", &nvcDriver{})
+	db, err := Open("NamedValueCheck", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	_, err = db.ExecContext(ctx, "WIPE")
+	if err != nil {
+		t.Fatal("exec wipe", err)
+	}
+
+	_, err = db.ExecContext(ctx, "CREATE|keys|dec1=any,str1=string,out1=string,array1=any")
+	if err != nil {
+		t.Fatal("exec create", err)
+	}
+
+	o1 := ""
+	_, err = db.ExecContext(ctx, "INSERT|keys|dec1=?A,str1=?,out1=?O1,array1=?", Named("A", decimalInt{123}), "hello", Named("O1", Out{Dest: &o1}), []int64{42, 128, 707}, doNotInclude{})
+	if err != nil {
+		t.Fatal("exec insert", err)
+	}
+	var (
+		str1 string
+		dec1 decimalInt
+		arr1 []int64
+	)
+	err = db.QueryRowContext(ctx, "SELECT|keys|dec1,str1,array1|").Scan(&dec1, &str1, &arr1)
+	if err != nil {
+		t.Fatal("select", err)
+	}
+
+	list := []struct{ got, want any }{
+		{o1, "from-server"},
+		{dec1, decimalInt{123}},
+		{str1, "hello"},
+		{arr1, []int64{42, 128, 707}},
+	}
+
+	for index, item := range list {
+		if !reflect.DeepEqual(item.got, item.want) {
+			t.Errorf("got %#v wanted %#v for index %d", item.got, item.want, index)
+		}
+	}
+}
+
+func TestNamedValueCheckerSkip(t *testing.T) {
+	Register("NamedValueCheckSkip", &nvcDriver{skipNamedValueCheck: true})
+	db, err := Open("NamedValueCheckSkip", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	_, err = db.ExecContext(ctx, "WIPE")
+	if err != nil {
+		t.Fatal("exec wipe", err)
+	}
+
+	_, err = db.ExecContext(ctx, "CREATE|keys|dec1=any")
+	if err != nil {
+		t.Fatal("exec create", err)
+	}
+
+	_, err = db.ExecContext(ctx, "INSERT|keys|dec1=?A", Named("A", decimalInt{123}))
+	if err == nil {
+		t.Fatalf("expected error with bad argument, got %v", err)
+	}
+}
+
+func TestOpenConnector(t *testing.T) {
+	Register("testctx", &fakeDriverCtx{})
+	db, err := Open("testctx", "people")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	c, ok := db.connector.(*fakeConnector)
+	if !ok {
+		t.Fatal("not using *fakeConnector")
+	}
+
+	if err := db.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	if !c.closed {
+		t.Fatal("connector is not closed")
+	}
+}
+
+type ctxOnlyDriver struct {
+	fakeDriver
+}
+
+func (d *ctxOnlyDriver) Open(dsn string) (driver.Conn, error) {
+	conn, err := d.fakeDriver.Open(dsn)
+	if err != nil {
+		return nil, err
+	}
+	return &ctxOnlyConn{fc: conn.(*fakeConn)}, nil
+}
+
+var (
+	_ driver.Conn           = &ctxOnlyConn{}
+	_ driver.QueryerContext = &ctxOnlyConn{}
+	_ driver.ExecerContext  = &ctxOnlyConn{}
+)
+
+type ctxOnlyConn struct {
+	fc *fakeConn
+
+	queryCtxCalled bool
+	execCtxCalled  bool
+}
+
+func (c *ctxOnlyConn) Begin() (driver.Tx, error) {
+	return c.fc.Begin()
+}
+
+func (c *ctxOnlyConn) Close() error {
+	return c.fc.Close()
+}
+
+// Prepare is still part of the Conn interface, so while it isn't used
+// must be defined for compatibility.
+func (c *ctxOnlyConn) Prepare(q string) (driver.Stmt, error) {
+	panic("not used")
+}
+
+func (c *ctxOnlyConn) PrepareContext(ctx context.Context, q string) (driver.Stmt, error) {
+	return c.fc.PrepareContext(ctx, q)
+}
+
+func (c *ctxOnlyConn) QueryContext(ctx context.Context, q string, args []driver.NamedValue) (driver.Rows, error) {
+	c.queryCtxCalled = true
+	return c.fc.QueryContext(ctx, q, args)
+}
+
+func (c *ctxOnlyConn) ExecContext(ctx context.Context, q string, args []driver.NamedValue) (driver.Result, error) {
+	c.execCtxCalled = true
+	return c.fc.ExecContext(ctx, q, args)
+}
+
+// TestQueryExecContextOnly ensures drivers only need to implement QueryContext
+// and ExecContext methods.
+func TestQueryExecContextOnly(t *testing.T) {
+	// Ensure connection does not implement non-context interfaces.
+	var connType driver.Conn = &ctxOnlyConn{}
+	if _, ok := connType.(driver.Execer); ok {
+		t.Fatalf("%T must not implement driver.Execer", connType)
+	}
+	if _, ok := connType.(driver.Queryer); ok {
+		t.Fatalf("%T must not implement driver.Queryer", connType)
+	}
+
+	Register("ContextOnly", &ctxOnlyDriver{})
+	db, err := Open("ContextOnly", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	conn, err := db.Conn(ctx)
+	if err != nil {
+		t.Fatal("db.Conn", err)
+	}
+	defer conn.Close()
+	coc := conn.dc.ci.(*ctxOnlyConn)
+	coc.fc.skipDirtySession = true
+
+	_, err = conn.ExecContext(ctx, "WIPE")
+	if err != nil {
+		t.Fatal("exec wipe", err)
+	}
+
+	_, err = conn.ExecContext(ctx, "CREATE|keys|v1=string")
+	if err != nil {
+		t.Fatal("exec create", err)
+	}
+	expectedValue := "value1"
+	_, err = conn.ExecContext(ctx, "INSERT|keys|v1=?", expectedValue)
+	if err != nil {
+		t.Fatal("exec insert", err)
+	}
+	rows, err := conn.QueryContext(ctx, "SELECT|keys|v1|")
+	if err != nil {
+		t.Fatal("query select", err)
+	}
+	v1 := ""
+	for rows.Next() {
+		err = rows.Scan(&v1)
+		if err != nil {
+			t.Fatal("rows scan", err)
+		}
+	}
+	rows.Close()
+
+	if v1 != expectedValue {
+		t.Fatalf("expected %q, got %q", expectedValue, v1)
+	}
+
+	if !coc.execCtxCalled {
+		t.Error("ExecContext not called")
+	}
+	if !coc.queryCtxCalled {
+		t.Error("QueryContext not called")
+	}
+}
+
+type alwaysErrScanner struct{}
+
+var errTestScanWrap = errors.New("errTestScanWrap")
+
+func (alwaysErrScanner) Scan(any) error {
+	return errTestScanWrap
+}
+
+// Issue 38099: Ensure that Rows.Scan properly wraps underlying errors.
+func TestRowsScanProperlyWrapsErrors(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	rows, err := db.Query("SELECT|people|age|")
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+
+	var res alwaysErrScanner
+
+	for rows.Next() {
+		err = rows.Scan(&res)
+		if err == nil {
+			t.Fatal("expecting back an error")
+		}
+		if !errors.Is(err, errTestScanWrap) {
+			t.Fatalf("errors.Is mismatch\n%v\nWant: %v", err, errTestScanWrap)
+		}
+		// Ensure that error substring matching still correctly works.
+		if !strings.Contains(err.Error(), errTestScanWrap.Error()) {
+			t.Fatalf("Error %v does not contain %v", err, errTestScanWrap)
+		}
+	}
+}
+
+// badConn implements a bad driver.Conn, for TestBadDriver.
+// The Exec method panics.
+type badConn struct{}
+
+func (bc badConn) Prepare(query string) (driver.Stmt, error) {
+	return nil, errors.New("badConn Prepare")
+}
+
+func (bc badConn) Close() error {
+	return nil
+}
+
+func (bc badConn) Begin() (driver.Tx, error) {
+	return nil, errors.New("badConn Begin")
+}
+
+func (bc badConn) Exec(query string, args []driver.Value) (driver.Result, error) {
+	panic("badConn.Exec")
+}
+
+// badDriver is a driver.Driver that uses badConn.
+type badDriver struct{}
+
+func (bd badDriver) Open(name string) (driver.Conn, error) {
+	return badConn{}, nil
+}
+
+// Issue 15901.
+func TestBadDriver(t *testing.T) {
+	Register("bad", badDriver{})
+	db, err := Open("bad", "ignored")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		if r := recover(); r == nil {
+			t.Error("expected panic")
+		} else {
+			if want := "badConn.Exec"; r.(string) != want {
+				t.Errorf("panic was %v, expected %v", r, want)
+			}
+		}
+	}()
+	defer db.Close()
+	db.Exec("ignored")
+}
+
+type pingDriver struct {
+	fails bool
+}
+
+type pingConn struct {
+	badConn
+	driver *pingDriver
+}
+
+var pingError = errors.New("Ping failed")
+
+func (pc pingConn) Ping(ctx context.Context) error {
+	if pc.driver.fails {
+		return pingError
+	}
+	return nil
+}
+
+var _ driver.Pinger = pingConn{}
+
+func (pd *pingDriver) Open(name string) (driver.Conn, error) {
+	return pingConn{driver: pd}, nil
+}
+
+func TestPing(t *testing.T) {
+	driver := &pingDriver{}
+	Register("ping", driver)
+
+	db, err := Open("ping", "ignored")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := db.Ping(); err != nil {
+		t.Errorf("err was %#v, expected nil", err)
+		return
+	}
+
+	driver.fails = true
+	if err := db.Ping(); err != pingError {
+		t.Errorf("err was %#v, expected pingError", err)
+	}
+}
+
+// Issue 18101.
+func TestTypedString(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	type Str string
+	var scanned Str
+
+	err := db.QueryRow("SELECT|people|name|name=?", "Alice").Scan(&scanned)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := Str("Alice")
+	if scanned != expected {
+		t.Errorf("expected %+v, got %+v", expected, scanned)
+	}
+}
+
+func BenchmarkConcurrentDBExec(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentDBExecTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentStmtQuery(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentStmtQueryTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentStmtExec(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentStmtExecTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentTxQuery(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentTxQueryTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentTxExec(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentTxExecTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentTxStmtQuery(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentTxStmtQueryTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentTxStmtExec(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentTxStmtExecTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentRandom(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentRandomTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkManyConcurrentQueries(b *testing.B) {
+	b.ReportAllocs()
+	// To see lock contention in Go 1.4, 16~ cores and 128~ goroutines are required.
+	const parallelism = 16
+
+	db := newTestDB(b, "magicquery")
+	defer closeDB(b, db)
+	db.SetMaxIdleConns(runtime.GOMAXPROCS(0) * parallelism)
+
+	stmt, err := db.Prepare("SELECT|magicquery|op|op=?,millis=?")
+	if err != nil {
+		b.Fatal(err)
+	}
+	defer stmt.Close()
+
+	b.SetParallelism(parallelism)
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			rows, err := stmt.Query("sleep", 1)
+			if err != nil {
+				b.Error(err)
+				return
+			}
+			rows.Close()
+		}
+	})
+}