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

telemachus
Python Testing With Pytest - Chapter 2, warnings for “unregistered custom marks” While running the smoke tests in Chapter 2, I get these...
New
yulkin
your book suggests to use Image.toByteData() to convert image to bytes, however I get the following error: "the getter ‘toByteData’ isn’t...
New
simonpeter
When I try the command to create a pair of migration files I get an error. user=> (create-migration "guestbook") Execution error (Ill...
New
leba0495
Hello! Thanks for the great book. I was attempting the Trie (chap 17) exercises and for number 4 the solution provided for the autocorre...
New
adamwoolhether
When trying to generate the protobuf .go file, I receive this error: Unknown flag: --go_opt libprotoc 3.12.3 MacOS 11.3.1 Googling ...
New
jgchristopher
“The ProductLive.Index template calls a helper function, live_component/3, that in turn calls on the modal component. ” Excerpt From: Br...
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
Henrai
Hi, I’m working on the Chapter 8 of the book. After I add add the point_offset, I’m still able to see acne: In the image above, I re...
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

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
siddhant3030
I’m thinking of buying a monitor that I can rotate to use as a vertical monitor? Also, I want to know if someone is using it for program...
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
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
Create efficient, elegant software tests in pytest, Python's most powerful testing framework. Brian Okken @brianokken Edited by Kat...
New
PragmaticBookshelf
Author Spotlight Mike Riley @mriley This month, we turn the spotlight on Mike Riley, author of Portable Python Projects. Mike’s book ...
New
New
PragmaticBookshelf
Author Spotlight: Peter Ullrich @PJUllrich Data is at the core of every business, but it is useless if nobody can access and analyze ...
New
AstonJ
If you’re getting errors like this: psql: error: connection to server on socket “/tmp/.s.PGSQL.5432” failed: No such file or directory ...
New
PragmaticBookshelf
Use advanced functional programming principles, practical Domain-Driven Design techniques, and production-ready Elixir code to build scal...
New

Latest in Functional Programming in Java, Second Edition

Functional Programming in Java, Second Edition Portal

Sub Categories: