dtonhofer

dtonhofer

Functional Programming in Java, Second Edition: Functional Programming in Java, Second Edition: JUnit code improvements for Chapter 11, pages 184 ff “Refactoring More Complex loops”

The same remarks apply as for “Refactoring the Traditional for Loop”

  • No init()
  • Classes under test implement a common interface that is called in tests.
  • Negative tests which apply for input less than 1900, resulting in exceptions.
package chapter11;

import org.junit.jupiter.api.Test;

import java.time.Year;
import java.util.stream.IntStream;

import static org.junit.jupiter.api.Assertions.*;

// Everything is inside the MoreComplexLoopTest class for convenience.
// Documentation for java.time.Year.isLeap()
// https://docs.oracle.com/javase/8/docs/api/java/time/Year.html#isLeap--

public class MoreComplexLoopTest {

    interface LeapYears {

        int countFrom1900(int upTo);

    }

    static class LeapYearCountBefore implements LeapYears {

        public int countFrom1900(int upTo) {
            if (upTo < 1900) {
                throw new IllegalArgumentException("The passed value is < 1900: " + upTo);
            }
            int count = 0;
            for (int year = 1900; year <= upTo; year += 4) {
                if (Year.isLeap(year)) {
                    count++;
                }
            }
            return count;
        }

    }

    static class LeapYearCountAfter implements LeapYears {

        public int countFrom1900(int upTo) {
            if (upTo < 1900) {
                throw new IllegalArgumentException("The passed value is < 1900: " + upTo);
            }
            return (int) IntStream.iterate(1900, year -> year <= upTo, year -> year + 4)
                    .filter(Year::isLeap)
                    .count();
        }

    }

    private static void commonLeapYearsTests(final LeapYears leapYears) {
        assertAll(
                () -> assertEquals(0, leapYears.countFrom1900(1900)),
                () -> assertEquals(25, leapYears.countFrom1900(2000)),
                () -> assertEquals(27, leapYears.countFrom1900(2010)),
                () -> assertEquals(31, leapYears.countFrom1900(2025)),
                () -> assertEquals(49, leapYears.countFrom1900(2100)),
                () -> assertEquals(267, leapYears.countFrom1900(3000)),
                () -> assertThrows(IllegalArgumentException.class, () -> leapYears.countFrom1900(1800))
        );
    }

    @Test
    void leapYearCountBefore() {
        commonLeapYearsTests(new LeapYearCountBefore());
    }

    @Test
    void leapYearCountAfter() {
        commonLeapYearsTests(new LeapYearCountAfter());
    }

}

Where Next?

Popular Pragmatic Bookshelf topics Top

jimschubert
In Chapter 3, the source for index introduces Config on page 31, followed by more code including tests; Config isn’t introduced until pag...
New
mikecargal
Title: Hands-On Rust (Chapter 11: prefab) Just played a couple of amulet-less games. With a bit of debugging, I believe that your can_p...
New
New
Chrichton
Dear Sophie. I tried to do the “Authorization” exercise and have two questions: When trying to plug in an email-service, I found the ...
New
adamwoolhether
Is there any place where we can discuss the solutions to some of the exercises? I can figure most of them out, but am having trouble with...
New
tkhobbes
After some hassle, I was able to finally run bin/setup, now I have started the rails server but I get this error message right when I vis...
New
Keton
When running the program in chapter 8, “Implementing Combat”, the printout Health before attack was never printed so I assumed something ...
New
dtonhofer
@parrt In the context of Chapter 4.3, the grammar Java.g4, meant to parse Java 6 compilation units, no longer passes ANTLR (currently 4....
New
bjnord
Hello @herbert ! Trying to get the very first “Hello, Bracket Terminal!" example to run (p. 53). I develop on an Amazon EC2 instance runn...
New
davetron5000
Hello faithful readers! If you have tried to follow along in the book, you are asked to start up the dev environment via dx/build and ar...
New

Other popular topics Top

PragmaticBookshelf
Take your Go skills to the next level by learning how to design, develop, and deploy a distributed service. Start from the bare essential...
New
PragmaticBookshelf
Free and open source software is the default choice for the technologies that run our world, and it’s built and maintained by people like...
New
ohm
Which, if any, games do you play? On what platform? I just bought (and completed) Minecraft Dungeons for my Nintendo Switch. Other than ...
New
AstonJ
Curious to know which languages and frameworks you’re all thinking about learning next :upside_down_face: Perhaps if there’s enough peop...
New
AstonJ
I ended up cancelling my Moonlander order as I think it’s just going to be a bit too bulky for me. I think the Planck and the Preonic (o...
New
AstonJ
If you get Can't find emacs in your PATH when trying to install Doom Emacs on your Mac you… just… need to install Emacs first! :lol: bre...
New
Help
I am trying to crate a game for the Nintendo switch, I wanted to use Java as I am comfortable with that programming language. Can you use...
New
PragmaticBookshelf
Author Spotlight: Peter Ullrich @PJUllrich Data is at the core of every business, but it is useless if nobody can access and analyze ...
New
New
AstonJ
This is a very quick guide, you just need to: Download LM Studio: https://lmstudio.ai/ Click on search Type DeepSeek, then select the o...
New

Latest in Functional Programming in Java, Second Edition

Functional Programming in Java, Second Edition Portal

Sub Categories: