dtonhofer

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.

Where Next?

Popular Pragmatic Bookshelf topics Top

belgoros
Following the steps described in Chapter 6 of the book, I’m stuck with running the migration as described on page 84: bundle exec sequel...
New
jamis
The following is cross-posted from the original Ray Tracer Challenge forum, from a post by garfieldnate. I’m cross-posting it so that the...
New
brunogirin
When trying to run tox in parallel as explained on page 151, I got the following error: tox: error: argument -p/–parallel: expected one...
New
oaklandgit
Hi, I completed chapter 6 but am getting the following error when running: thread 'main' panicked at 'Failed to load texture: IoError(O...
New
hazardco
On page 78 the following code appears: <%= link_to ‘Destroy’, product, class: ‘hover:underline’, method: :delete, data: { confirm...
New
akraut
The markup used to display the uploaded image results in a Phoenix.LiveView.HTMLTokenizer.ParseError error. lib/pento_web/live/product_l...
New
taguniversalmachine
Hi, I am getting an error I cannot figure out on my test. I have what I think is the exact code from the book, other than I changed “us...
New
jonmac
The allprojects block listed on page 245 produces the following error when syncing gradle: “org.gradle.api.GradleScriptException: A prob...
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
dachristenson
@mfazio23 Android Studio will not accept anything I do when trying to use the Transformations class, as described on pp. 140-141. Googl...
New

Other popular topics Top

PragmaticBookshelf
Brace yourself for a fun challenge: build a photorealistic 3D renderer from scratch! In just a couple of weeks, build a ray tracer that r...
New
PragmaticBookshelf
Learn from the award-winning programming series that inspired the Elixir language, and go on a step-by-step journey through the most impo...
New
PragmaticBookshelf
Write Elixir tests that you can be proud of. Dive into Elixir’s test philosophy and gain mastery over the terminology and concepts that u...
New
PragmaticBookshelf
Learn different ways of writing concurrent code in Elixir and increase your application's performance, without sacrificing scalability or...
New
DevotionGeo
The V Programming Language Simple language for building maintainable programs V is already mentioned couple of times in the forum, but I...
New
AstonJ
We’ve talked about his book briefly here but it is quickly becoming obsolete - so he’s decided to create a series of 7 podcasts, the firs...
New
New
PragmaticBookshelf
Author Spotlight: VM Brasseur @vmbrasseur We have a treat for you today! We turn the spotlight onto Open Source as we sit down with V...
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: