import static java.lang.Long.MAX_VALUE;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class OverflowLongSumTest
{
	@Test public void testIt() throws SQLException
	{
		insert(42);
		assertSum(42); // ok

		insert(MAX_VALUE - 42);
		assertSum(MAX_VALUE); // ok

		insert(1);
		assertSum(MAX_VALUE); // wrong, should raise an exception

		insert(5);
		assertSum(MAX_VALUE); // wrong, should raise an exception
	}

	private void insert(final long value) throws SQLException
	{
		try(Statement st = connection.createStatement())
		{
			st.execute("INSERT INTO tab VALUES (" + value + ")");
		}
	}

	private void assertSum(final long expected) throws SQLException
	{
		try(
			Statement st = connection.createStatement();
			ResultSet rs = st.executeQuery("SELECT SUM(col) FROM tab"))
		{
			assertTrue(rs.next());
			assertEquals(expected, rs.getLong(1));
		}
	}


	private Connection connection;

	@Before public void before() throws SQLException
	{
		connection = DriverManager.getConnection("jdbc:mysql://localhost/xxx", "xxx", "xxx");
		try(Statement st = connection.createStatement())
		{
			st.execute("DROP TABLE IF EXISTS tab");
		}
		try(Statement st = connection.createStatement())
		{
			st.execute("CREATE TABLE tab ( col bigint )");
		}
	}

	@After public void after() throws SQLException
	{
		try(Statement st = connection.createStatement())
		{
			st.execute("DROP TABLE IF EXISTS tab");
		}
		connection.close();
	}
}