https://codeiq.jp/magazine/2013/11/1475/ のテストを考えてみる

DateFactory.java

import java.util.Calendar;
import java.util.Date;

public interface DateFactory {
    Calendar getCalendar();
}

Greeter.java

import java.util.Calendar;

public class Greeter {

    private Calendar calendar;

    public Greeter(Calendar calendar) {
        this.calendar = calendar;
    }

    public String greeting() {
        int hourOfDay = calendar.get(Calendar.HOUR_OF_DAY);
        if (hourOfDay >= 5 && hourOfDay < 12) {
            return "おはようございます";
        }
        if (hourOfDay >= 12 && hourOfDay < 18) {
            return "こんにちは";
        }
        return "こんばんは";
    }
}

GreeterTest.java

import org.junit.Test;

import java.util.Calendar;
import java.util.Date;
import java.util.SimpleTimeZone;
import java.util.TimeZone;

import static org.hamcrest.CoreMatchers.*;
import static org.junit.Assert.*;

public class GreeterTest {

    @Test
    public void test_朝AM5時から12時の間() throws Exception{
        Calendar date = getDate(5, 0, 1);
        Greeter greeter = new Greeter(date);
        String message = greeter.greeting();
        assertThat(message, is("おはようございます"));
    }

    @Test
    public void test_朝5時ちょうど() throws Exception {
        Calendar date = getDate(5, 0, 0);
        Greeter greeter = new Greeter(date);
        String message = greeter.greeting();
        assertThat(message, is("おはようございます"));
    }

    @Test
    public void test_11時59分59秒() throws Exception {
        Calendar date = getDate(11, 59, 59);
        Greeter greeter = new Greeter(date);
        String message = greeter.greeting();
        assertThat(message, is("おはようございます"));
    }

    @Test
    public void test_12時から18間() throws Exception{
        Calendar date = getDate(15, 30, 0);
        Greeter greeter = new Greeter(date);
        String message = greeter.greeting();
        assertThat(message, is("こんにちは"));
    }

    @Test
    public void test_12時ちょうど() throws Exception{
        Calendar date = getDate(12, 0, 0);
        Greeter greeter = new Greeter(date);
        String message = greeter.greeting();
        assertThat(message, is("こんにちは"));
    }

    @Test
    public void test_17時59分59秒() throws Exception{
        Calendar date = getDate(17, 59, 59);
        Greeter greeter = new Greeter(date);
        String message = greeter.greeting();
        assertThat(message, is("こんにちは"));
    }

    @Test
    public void test_18時から5時のあいだ() throws  Exception{
        Calendar date = getDate(19, 59, 59);
        Greeter greeter = new Greeter(date);
        String message = greeter.greeting();
        assertThat(message, is("こんばんは"));
    }

    @Test
    public void test_18時ちょうど() throws  Exception{
        Calendar date = getDate(18, 0, 0);
        Greeter greeter = new Greeter(date);
        String message = greeter.greeting();
        assertThat(message, is("こんばんは"));
    }

    @Test
    public void test_4時59分59秒() throws  Exception{
        Calendar date = getDate(4, 59, 59);
        Greeter greeter = new Greeter(date);
        String message = greeter.greeting();
        assertThat(message, is("こんばんは"));
    }

    private Calendar getDate(final int hour, final int min, final int second){
        final int year = 2013;
        final int month = Calendar.JANUARY;
        final int day = 2;
        DateFactory factory = new DateFactory() {
            @Override
            public Calendar getCalendar() {
                Calendar cal  = Calendar.getInstance(TimeZone.getTimeZone("Asia/Tokyo"));
                cal.clear();
                cal.set(year, month, day, hour, min, second);
                return cal;
            }
        };
        return factory.getCalendar();
    }
}