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

New
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
herminiotorres
Hi @Margaret , On page VII the book tells us the example and snippets will be all using Elixir version 1.11 But on page 3 almost the en...
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
HarryDeveloper
Hi @venkats, It has been mentioned in the description of ‘Supervisory Job’ title that 2 things as mentioned below result in the same eff...
New
AndyDavis3416
@noelrappin Running the webpack dev server, I receive the following warning: ERROR in tsconfig.json TS18003: No inputs were found in c...
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
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
rainforest
Hi, I’ve got a question about the implementation of PubSub when using a Phoenix.Socket.Transport behaviour rather than channels. Before ...
New
redconfetti
Docker-Machine became part of the Docker Toolbox, which was deprecated in 2020, long after Docker Desktop supported Docker Engine nativel...
New

Other popular topics Top

Devtalk
Hello Devtalk World! Please let us know a little about who you are and where you’re from :nerd_face:
New
Rainer
My first contact with Erlang was about 2 years ago when I used RabbitMQ, which is written in Erlang, for my job. This made me curious and...
New
AstonJ
This looks like a stunning keycap set :orange_heart: A LEGENDARY KEYBOARD LIVES ON When you bought an Apple Macintosh computer in the e...
New
New
Margaret
Hello everyone! This thread is to tell you about what authors from The Pragmatic Bookshelf are writing on Medium.
1147 29841 760
New
AstonJ
Biggest jackpot ever apparently! :upside_down_face: I don’t (usually) gamble/play the lottery, but working on a program to predict the...
New
PragmaticBookshelf
Build efficient applications that exploit the unique benefits of a pure functional language, learning from an engineer who uses Haskell t...
New
New
New
First poster: AstonJ
Jan | Rethink the Computer. Jan turns your computer into an AI machine by running LLMs locally on your computer. It’s a privacy-focus, l...
New

Latest in Functional Programming in Java, Second Edition

Functional Programming in Java, Second Edition Portal

Sub Categories: