dtonhofer
Functional Programming in Java, Second Edition: Code reorganization into JUnit tests rather than individual main-adorned classes
This may be too extensive to change, but I would like to see the code example not as a series of classes with main() but as JUnit test classes.
One can then have all the code for one chapter in single class, and execute the individual methods, each corresponding to an example, directly from the IDE, without messing around with calling this or that main().
I suppose everyone knowledgeable of Java knows about JUnit at this point.
For example, for a part of chapter 3:
import org.junit.jupiter.api.Test;
import java.io.File;
import java.io.IOException;
import java.nio.file.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import static java.util.stream.Collectors.toList;
public class MyTest {
private final static String theDir = "foo";
// "Listing Select Files in a Directory", p.61
@Test
public void listSelectFilesTheHardWay() {
final String[] files =
new File(theDir).list(new java.io.FilenameFilter() {
public boolean accept(final File _dir, final String name) {
return name.endsWith(".java");
}
});
String res =
(files == null) ?
("Looks like '" + theDir + "' is not a directory") :
(Arrays.stream(files).collect(Collectors.joining("\n")));
System.out.println(res);
}
// "Listing Select Files in a Directory", p.61
@Test
public void listSelectFilesTheGoodWay() {
try {
Files.newDirectoryStream(
Paths.get(theDir), path -> path.toString().endsWith(".java"))
.forEach(System.out::println);
} catch (IOException ex) {
System.out.println("Looks like '" + theDir + "' is not a directory, or something");
}
}
}
If one loads this into the IDE, one just needs to hit the green arrows next to the @Test annotations for great results.
P.S.
I just noticed that an actual main() makes an appearance on p.69, like a blast from the past. It really would look better as a test case.
Popular Pragmatic Bookshelf topics
Python Testing With Pytest - Chapter 2, warnings for “unregistered custom marks”
While running the smoke tests in Chapter 2, I get these...
New
Many tasks_proj/tests directories exist in chapters 2, 3, 5 that have tests that use the custom markers smoke and get, which are not decl...
New
I thought that there might be interest in using the book with Rails 6.1 and Ruby 2.7.2. I’ll note what I needed to do differently here.
...
New
Title: Hands-on Rust: question about get_component (page 295)
(feel free to respond. “You dug you’re own hole… good luck”)
I have somet...
New
Title: Intuitive Python: docker run… denied error (page 2)
Attempted to run the docker command in both CLI and Powershell
PS C:\Users\r...
New
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
When installing Cards as an editable package, I get the following error:
ERROR: File “setup.py” not found. Directory cannot be installe...
New
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
@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
Getting an error when installing the dependencies at the start of this chapter:
could not compile dependency :exla, "mix compile" failed...
New
Other popular topics
poll
poll
Be sure to check out @Dusty’s article posted here: An Introduction to Alternative Keyboard Layouts It’s one of the best write-...
New
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
Crystal recently reached version 1. I had been following it for awhile but never got to really learn it. Most languages I picked up out o...
New
Create efficient, elegant software tests in pytest, Python's most powerful testing framework.
Brian Okken @brianokken
Edited by Kat...
New
Hi folks,
I don’t know if I saw this here but, here’s a new programming language, called Roc
Reminds me a bit of Elm and thus Haskell. ...
New
A few weeks ago I started using Warp a terminal written in rust. Though in it’s current state of development there are a few caveats (tab...
New
Author Spotlight
Rebecca Skinner
@RebeccaSkinner
Welcome to our latest author spotlight, where we sit down with Rebecca Skinner, auth...
New
Get the comprehensive, insider information you need for Rails 8 with the new edition of this award-winning classic.
Sam Ruby @rubys
...
New
This is cool!
DEEPSEEK-V3 ON M4 MAC: BLAZING FAST INFERENCE ON APPLE SILICON
We just witnessed something incredible: the largest open-s...
New
Ok, well here are some thoughts and opinions on some of the ergonomic keyboards I have, I guess like mini review of each that I use enoug...
New
Categories:
Sub Categories:
Popular Portals
- /elixir
- /rust
- /ruby
- /wasm
- /erlang
- /phoenix
- /keyboards
- /python
- /js
- /rails
- /security
- /go
- /swift
- /vim
- /clojure
- /emacs
- /haskell
- /java
- /svelte
- /onivim
- /typescript
- /kotlin
- /c-plus-plus
- /crystal
- /tailwind
- /react
- /gleam
- /ocaml
- /elm
- /flutter
- /vscode
- /ash
- /opensuse
- /html
- /centos
- /deepseek
- /php
- /zig
- /scala
- /sublime-text
- /lisp
- /textmate
- /react-native
- /debian
- /nixos
- /agda
- /kubuntu
- /arch-linux
- /django
- /deno
- /nodejs
- /revery
- /ubuntu
- /manjaro
- /spring
- /diversity
- /lua
- /julia
- /markdown
- /c








