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

abtin
page 20: … protoc command… I had to additionally run the following go get commands in order to be able to compile protobuf code using go...
New
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
jeffmcompsci
Title: Design and Build Great Web APIs - typo “https://company-atk.herokuapp.com/2258ie4t68jv” (page 19, third bullet in URL list) Typo:...
New
Mmm
Hi, build fails on: bracket-lib = “~0.8.1” when running on Mac Mini M1 Rust version 1.5.0: Compiling winit v0.22.2 error[E0308]: mi...
New
jskubick
I’m under the impression that when the reader gets to page 136 (“View Data with the Database Inspector”), the code SHOULD be able to buil...
New
adamwoolhether
I’m not quite sure what’s going on here, but I’m unable to have to containers successfully complete the Readiness/Liveness checks. I’m im...
New
hgkjshegfskef
The test is as follows: Scenario: Intersecting a scaled sphere with a ray Given r ← ray(point(0, 0, -5), vector(0, 0, 1)) And s ← sphere...
New
brunogirin
When installing Cards as an editable package, I get the following error: ERROR: File “setup.py” not found. Directory cannot be installe...
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
mcpierce
@mfazio23 I’ve applied the changes from Chapter 5 of the book and everything builds correctly and runs. But, when I try to start a game,...
New

Other popular topics Top

New
dasdom
No chair. I have a standing desk. This post was split into a dedicated thread from our thread about chairs :slight_smile:
New
DevotionGeo
I know that -t flag is used along with -i flag for getting an interactive shell. But I cannot digest what the man page for docker run com...
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 have seen the keycaps I want - they are due for a group-buy this week but won’t be delivered until October next year!!! :rofl: The Ser...
New
AstonJ
Do the test and post your score :nerd_face: :keyboard: If possible, please add info such as the keyboard you’re using, the layout (Qw...
New
AstonJ
If you are experiencing Rails console using 100% CPU on your dev machine, then updating your development and test gems might fix the issu...
New
First poster: bot
zig/http.zig at 7cf2cbb33ef34c1d211135f56d30fe23b6cacd42 · ziglang/zig. General-purpose programming language and toolchain for maintaini...
New
New
NewsBot
Node.js v22.14.0 has been released. Link: Release 2025-02-11, Version 22.14.0 'Jod' (LTS), @aduh95 · nodejs/node · GitHub
New

Latest in Functional Programming in Java, Second Edition

Functional Programming in Java, Second Edition Portal

Sub Categories: