fix: avoid connection failure when DateStyle is set to ISO (#1081)

Default PostgreSQL configuration is DateStyle='iso, dmy', however pgjdbc should not raise errors
if DateStyle is just ISO

Note: PostgreSQL prints DateStyle value in upper case, and toUpperCase
was added just in case.

fixes #1080

CHANGELOG.md

@@ -5,6 +5,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).

## [Unreleased]

### Fixed
- Avoid connection failure when `DateStyle` is set to `ISO` [Issue 1080](https://github.com/pgjdbc/pgjdbc/issues/1080)

## [42.2.0] (2018-01-17)
### Added
- Support SCRAM-SHA-256 for PostgreSQL 10 in the JDBC 4.2 version (Java 8+) using the Ongres SCRAM library. [PR 842](https://github.com/pgjdbc/pgjdbc/pull/842)

pgjdbc/src/main/java/org/postgresql/core/v3/QueryExecutorImpl.java

@@ -2593,7 +2593,8 @@ public void receiveParameterStatus() throws IOException, SQLException {
          value), PSQLState.CONNECTION_FAILURE);
    }

    if (name.equals("DateStyle") && !value.startsWith("ISO,")) {
    if (name.equals("DateStyle") && !value.startsWith("ISO")
        && !value.toUpperCase().startsWith("ISO")) {
      close(); // we're screwed now; we can't trust any subsequent date.
      throw new PSQLException(GT.tr(
          "The server''s DateStyle parameter was changed to {0}. The JDBC driver requires DateStyle to begin with ISO for correct operation.",

pgjdbc/src/test/java/org/postgresql/test/jdbc2/DateStyleTest.java

@@ -0,0 +1,62 @@
/*
 * Copyright (c) 2018, PostgreSQL Global Development Group
 * See the LICENSE file in the project root for more information.
 */

package org.postgresql.test.jdbc2;

import org.postgresql.test.TestUtil;
import org.postgresql.util.PSQLState;

import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;

import java.sql.SQLException;
import java.sql.Statement;
import java.util.Arrays;

@RunWith(Parameterized.class)
public class DateStyleTest extends BaseTest4 {

  @Parameterized.Parameter(0)
  public String dateStyle;

  @Parameterized.Parameter(1)
  public boolean shouldPass;


  @Parameterized.Parameters(name = "dateStyle={0}, shouldPass={1}")
  public static Iterable<Object[]> data() {
    return Arrays.asList(new Object[][]{
        {"iso, mdy", true},
        {"ISO", true},
        {"ISO,ymd", true},
        {"PostgreSQL", false}
    });
  }

  @Test
  public void conenct() throws SQLException {
    Statement st = con.createStatement();
    try {
      st.execute("set DateStyle='" + dateStyle + "'");
      if (!shouldPass) {
        Assert.fail("Set DateStyle=" + dateStyle + " should not be allowed");
      }
    } catch (SQLException e) {
      if (shouldPass) {
        throw new IllegalStateException("Set DateStyle=" + dateStyle
            + " should be fine, however received " + e.getMessage(), e);
      }
      if (PSQLState.CONNECTION_FAILURE.getState().equals(e.getSQLState())) {
        return;
      }
      throw new IllegalStateException("Set DateStyle=" + dateStyle
          + " should result in CONNECTION_FAILURE error, however received " + e.getMessage(), e);
    } finally {
      TestUtil.closeQuietly(st);
    }
  }
}

pgjdbc/src/test/java/org/postgresql/test/jdbc2/Jdbc2TestSuite.java

@@ -31,6 +31,7 @@

        DriverTest.class,
        ConnectionTest.class,
        DateStyleTest.class,
        DatabaseMetaDataTest.class,
        DatabaseMetaDataPropertiesTest.class,
        SearchPathLookupTest.class,