dtonhofer

dtonhofer

Functional Programming in Java, Second Edition: p.90 CalculateNAVTest erroneous

On page 90, CalculateNAVTest.java:

public class CalculateNAVTest {

   @Test
   public void computeStockWorth() {
      final CalculateNAV calculateNAV = new CalculateNAV(ticker -> new BigDecimal("6.01"));
      BigDecimal expected = new BigDecimal("6010.00");
      assertEquals(0, calculateNAV.computeStockWorth("GOOG", 1000).compareTo(expected), 0.001);
   }

The assertEquals() makes no sense.

It runs BigDecimal.compare( new BigDecimal("6010") , new BigDecimal("6010.00") ) which is either -1, 0 or +1, and compares it with 0 with an irrelevant precision of 0.001.

What we want is:

public class CalculateNAVTest {

   @Test
    public void computeStockWorth() {
        final CalculateNAV calculateNAV = new CalculateNAV(ticker -> new BigDecimal("6.01"));
        BigDecimal expected = new BigDecimal("6010.00");
        BigDecimal actual = calculateNAV.computeStockWorth("GOOG", 1000);
        BigDecimal delta = actual.subtract(expected);
        assertEquals(delta.doubleValue(), 0, 0.001);
    }

JavaDoc for BigDecimal.compare():

Marked As Solved

venkats

venkats

Author of Programming Kotlin, Rediscovering JavaScript (and 6 other titles)

Very good catch. Fixed. Thank you.

Where Next?

Popular Pragmatic Bookshelf topics Top

johnp
Running the examples in chapter 5 c under pytest 5.4.1 causes an AttributeError: ‘module’ object has no attribute ‘config’. In particula...
New
jdufour
Hello! On page xix of the preface, it says there is a community forum "… for help if your’re stuck on one of the exercises in this book… ...
New
raul
Hi Travis! Thank you for the cool book! :slight_smile: I made a list of issues and thought I could post them chapter by chapter. I’m rev...
New
nicoatridge
Hi, I have just acquired Michael Fazio’s “Kotlin and Android Development” to learn about game programming for Android. I have a game in p...
New
dsmith42
Hey there, I’m enjoying this book and have learned a few things alredayd. However, in Chapter 4 I believe we are meant to see the “>...
New
kolossal
Hi, I need some help, I’m new to rust and was learning through your book. but I got stuck at the last stage of distribution. Whenever I t...
New
a.zampa
@mfazio23 I’m following the indications of the book and arriver ad chapter 10, but the app cannot be compiled due to an error in the Bas...
New
gorkaio
root_layout: {PentoWeb.LayoutView, :root}, This results in the following following error: no “root” html template defined for PentoWeb...
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
dachristenson
I’ve got to the end of Ch. 11, and the app runs, with all tabs displaying what they should – at first. After switching around between St...
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
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
Exadra37
I am thinking in building or buy a desktop computer for programing, both professionally and on my free time, and my choice of OS is Linux...
New
brentjanderson
Bought the Moonlander mechanical keyboard. Cherry Brown MX switches. Arms and wrists have been hurting enough that it’s time I did someth...
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
dimitarvp
Small essay with thoughts on macOS vs. Linux: I know @Exadra37 is just waiting around the corner to scream at me “I TOLD YOU SO!!!” but I...
New
PragmaticBookshelf
Tailwind CSS is an exciting new CSS framework that allows you to design your site by composing simple utility classes to create complex e...
New
PragmaticBookshelf
Rails 7 completely redefines what it means to produce fantastic user experiences and provides a way to achieve all the benefits of single...
New
New

Latest in Functional Programming in Java, Second Edition

Functional Programming in Java, Second Edition Portal

Sub Categories: