Exploration de Java 8 java.time

Java8JavaTimeUnitTest.java

package com.scratch.test;

import org.junit.Test;

import java.text.SimpleDateFormat;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.util.Date;
import java.util.TimeZone;

import static org.fest.assertions.Assertions.assertThat;

public class Java8JavaTimeUnitTest
{
    @Test
    public void aJava_Util_DateIsAlmostLikeAJava_Time_InstantInUTC()
    {
        final Date date = new Date( 0L );
        assertThat( date.getTime() ).isEqualTo( 0L );

        final Instant instant = date.toInstant();
        assertThat( instant.getEpochSecond() ).isEqualTo( 0 );
    }

    @Test
    public void java_Util_DateToStringIsInconsistentWithJava_Time_InstantToString()
    {
        final Date date = new Date( 0L );
        final Instant instant = date.toInstant();

        assertThat( TimeZone.getDefault().getID() ).isEqualTo( "Europe/Paris" );

        assertThat( instant.toString() ).isEqualTo( "1970-01-01T00:00:00Z" );
        assertThat( date.toString() ).isEqualTo( "Thu Jan 01 01:00:00 CET 1970" );
    }

    @Test
    public void java_Util_DateIsConvertedToStringUsingTheDefaultTimeZone()
    {
        final Date date = new Date( 0L );

        assertThat( TimeZone.getDefault().getID() ).isEqualTo( "Europe/Paris" );
        assertThat( date.toString() ).isEqualTo( "Thu Jan 01 01:00:00 CET 1970" );
    }

    @Test
    public void java_Util_DateIsFormatedUsingTheDefaultTimeZone()
    {
        final Date date = new Date( 0L );
        final SimpleDateFormat simpleDateFormat = new SimpleDateFormat( "yyyy-MM-dd'T'HH:mm:ss" );

        assertThat( simpleDateFormat.getTimeZone().getID() ).isEqualTo( "Europe/Paris" );
        assertThat( simpleDateFormat.format( date ) ).isEqualTo( "1970-01-01T01:00:00" );
    }

    @Test
    public void aJava_Time_InstantIsConvertedToAStringRegardlessOfTheDefaultTimeZone()
    {
        final Date date = new Date( 0L );
        final Instant instant = date.toInstant();

        assertThat( TimeZone.getDefault().getID() ).isEqualTo( "Europe/Paris" );
        assertThat( instant.toString() ).isEqualTo( "1970-01-01T00:00:00Z" );
    }

    @Test
    public void useUTCTimeZoneToConvertJava_Util_DateUsedAsTimeZoneLessDateTimeToJava_Time_LocalDateTime()
    {
        final Date date = new Date( 0L );
        final Instant instant = date.toInstant();
        final LocalDateTime localDateTime = LocalDateTime.ofInstant( instant, ZoneId.of( "UTC" ) );

        assertThat( localDateTime.getHour() ).isZero();
        assertThat( localDateTime.getMinute() ).isZero();
        assertThat( localDateTime.getSecond() ).isZero();

        assertThat( localDateTime.toString() ).isEqualTo( "1970-01-01T00:00" );
    }
}