const (
	// alwaysNewConn forces a new connection to the database.
	alwaysNewConn connReuseStrategy = iota
	// cachedOrNewConn returns a cached connection, if available, else waits
	// for one to become available (if MaxOpenConns has been reached) or
	// creates a new database connection.
	cachedOrNewConn
)

// driverConn wraps a driver.Conn with a mutex, to
// be held during all calls into the Conn. (including any calls onto

	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)
	}