A Strong Cup of Java

Hey everyone!

If you’re interested in the goings-on of the Java language, be sure to check out my new Web Series on IBM Developer called A Strong Cup of Java.

The show will focus on interesting topics in the world of Java.

Episode One is about Jakarta EE, where I talk about what Jakarta EE is, and how it got its name (whatever happened to J2EE?).

Episode Two covers the launch of Jakarta EE 8 (the first release of enterprise Java since Java EE 8 in 2017) that happened on September 10, 2019 in an all-day live stream called JakartaOne.

In the coming weeks, there will be eight more episodes published (I have a 10 episode committment from IBM for the series). With your support there may be more, so please watch!

Click here for the show notes page at IBM Developer.

If you have ideas for topics, please let me know. Thanks for reading!

–jsp

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JUnit Jupiter Annotations, Chapter 2

Overview

In part 1 I introduced you to JUnit 5 annotations:

  • @DisplayName
  • @Test

In this chapter, I’ll show you two more annotations:

  • @Disabled
  • @Nested

With code examples for both, and a video where I write code using these annotations.

You can download the complete sample application from GitHub if you like.

Let’s get started!

The Class Under Test

Before diving into the meat of this, let me show you the class under test. It’s called Echo, and it’s very simple (so as not to get in the way of the lesson):

public class Echo {
  public String echo(String stringToEcho) {
    return stringToEcho;
  }

  public Integer echo(Integer intToEcho) {
    return intToEcho;
  }

}

The class is pretty simple: its contract stipulates that it echoes whatever is passed, unchanged.

In true Test-Driven Development (TDD) style, you’ll write the implementation after you write the unit tests.

@Disabled

@Test
@Disabled
@DisplayName("A disabled test")
void testNotRun() {
  // This method will not run
}

Use this annotation to tell the JUnit platform not to run this test method. Notice that the method is annotated with the @Test annotation. Normally, JUnit would execute this method at the appropriate point in the test lifecycle, but annotating the method with @Disabled tells JUnit not to run it.

Why not just remove the @Test annotation? It might be good for documentation purposes to leave it annotated with @Test so you know it was a test method, or maybe you just want to temporarily disable the method.

@Nested

This is a super cool new feature of JUnit 5 that allows you to create nested (inner) classes that keep groups of tests together in the same main test class, but separate from the other test methods in that class.

In the case of the Echo class, both methods are called echo, so you need some way of distinguishing which echo overload you’re testing. You could do something like this:

@Test
public void testEcho_String() {
.
.
}

@Test
public void testEcho_Integer() {
.
.
}

And that would work just fine. But JUnit 5 and the Jupiter API give you the @Nested annotation. So let’s use it!

 
  @Nested
  public class StringEchoTest {

    @Test
    public void testEcho() {

      classUnderTest = new Echo();

      String expectedString = "This is a test";

      assertAll("String version of echo() method",
          // equals() should match, 
          /// but that is not good enough
          () -> assertEquals(expectedString, 
                 classUnderTest.echo(expectedString)),
          // hash codes should match, 
          /// but still not quite good enough
          () -> assertEquals(expectedString.hashCode(), 
                 classUnderTest.echo(expectedString).hashCode()),
          // This should do the trick
          () -> assertEquals(
              System.identityHashCode(expectedString),
               System.identityHashCode(
                classUnderTest.echo(expectedString))));
    }

  }

  @Nested
  public class IntegerEchoTest {

    @Test
    public void testEcho() {

      classUnderTest = new Echo();

      Integer expectedInteger = Integer.valueOf(238);

      assertAll("String version of echo() method",
          () -> assertEquals(expectedInteger, 
                 classUnderTest.echo(expectedInteger)),
          () -> assertEquals(expectedInteger.hashCode(), 
                 classUnderTest.echo(expectedInteger).hashCode()),
          () -> assertEquals(
              System.identityHashCode(expectedInteger),
                System.identityHashCode(
                 classUnderTest.echo(expectedInteger))));
    }
  }

Video

In the video below, I’ll go over these annotations in detail, and you can watch me explain the code as I write it.

Conclusion

In this article, I showed you some of the annotations from the JUnit Jupiter API you’re most likely to use. But there is a LOT more to JUnit than the Annotations.

Be sure to follow along with this series here on my blog, and the accompanying videos on my YouTube channel.

To learn more about the annotations provided by the JUnit Jupiter API visit the JUnit 5 User’s Guide.

Check out my IBM developerWorks JUnit 5 Tutorial Series:

Check out the first post in this series here.

 

Container Orchestration with Kubernetes, Part 5

Managing Kubernetes

Hey everybody! In this post, I’d like to talk about Container-centric infrastructure with Kubernetes. This is Part 5 of a series of posts on using installing and using Kubernetes.

If you missed Part 4 where I give you Install Kubernetes on your Computer (Minikube), make sure to check that out.

In this post I’ll show you two ways to manage your Kubernetes applications:

  • kubectl
  • Kubernetes Web UI Dashboard

The kubectl command

When Kubernetes starts a pod it’s isolated in its own network. So how do we interact with the application?

One way is through a proxy, which you can start in a separate terminal window. Start a new Terminal window and execute the kubectl proxy command.

kubectl proxy

By default the proxy uses port 8001, but you can specify a different port using the --port option.

kubectl proxy --port=8080

This starts the proxy using port 8080. Now you can connect to the cluster through port 8080 on your computer.

I’ve written a script to get the pod name and use it to access the application through the cluster’s REST interface. The script is called test-k8sdemo.sh and takes the port as an argument.

./test-k8sdemo.sh 8080

And there you see the output.

Now that we have an app up and running, let’s talk about how to manage it. You can use the kubectl command to get information about pods, deployments, and so on.

For example, you can show a listing of the deployments:

kubectl get deployments

Or of the pods:

kubectl get pods

You can even get detailed information about the pods:

kubectl describe pods

This produces a lot of output, but it’s valuable (if somewhat verbose) information.

Kubernetes Web UI Dashboard

Now I love the command line as much as anybody, but did you know that Kubernetes has a Web-based UI dashboard?

By default the Dashboard is not deployed. From the documentation, you can copy the command to create the deployment through the kubectl command:

kubectl create -f https://raw.githubusercontent.com/kubernetes/dashboard/master/src/deploy/recommended/kubernetes-dashboard.yaml

Paste the above command into the console to deploy it.

Make sure the proxy is running (I showed you how to do this in Part 4). Start the proxy in a separate Terminal window:

kubectl proxy --port=8001

Once the Dashboard is deployed you can access it from http://localhost:8001/ui.

You can see the same basic information as from the various kubectl commands, but in a UI. Here’s an example of what I see using Chrome:

Conclusion

Well, that’s it for this series. I hope you enjoyed it, and make sure to check out the video below that walks you through everything I covered in this blog series (it’s true what they say: a video is worth a thousand pictures!).

Want to know more?

If you want to learn more about Kubernetes, check out this post at IBM developerWorks: What is Kubernetes?

Be sure to check out the other posts in this series:

Check out this video at IBM developerWorks TV, where I show you everything I covered in Parts 1-5 of this series:

Introduction to Kubernetes:

Thanks for reading!

–jsp

Container Orchestration with Kubernetes, Part 4

Working with Kubernetes on your Computer (Minikube)

Hey everybody! In this post, I’d like to talk about Container-centric infrastructure with Kubernetes. This is Part 4 of a series of posts on using installing and using Kubernetes.

If you missed Part 3 where I give you Install Kubernetes on your Computer (Minikube), make sure to check that out.

The Application

So now you’re finally ready to start using Kubernetes. The first step in deploying a containerized application is, well, the application. I’ve put together some demo JavaScript code that you’ll run as a Node.js application.

Open a Terminal window or command prompt, navigate to a location on your computer where you want the code to land and clone the code from GitHub.

git clone https://github.com/makotogo/developerWorks

Navigate to the kubernetes directory and take a look at the JavaScript code. This toy application doesn’t do anything serious, just outputs a message to the console. But it’s enough for our purposes here.

Now run the application in Node.

node k8sdemo.js

Open a browser and point it to http://localhost:8080 to see the message.

And there it is. Now that you have an application, it’s time to containerize it.

Containerize the application

Here’s how you use Docker to do that. Take a look at the Dockerfile:

FROM node:6.11.4
EXPOSE 8080
COPY k8sdemo.js .
CMD node k8sdemo.js

Use this Docker definition to containerize the application. But before we can do that we need to start minikube, and I’ll show you why in a minute.

Execute the minikube start command:

minikube start

The first time Minikube runs, it has to download the ISO image to run inside of VirtualBox, and may take a minute or two depending on the speed of your internet connection. Once the image has been downloaded, minikube will start.

Minikube runs inside VirtualBox in its own VM. We need to make sure that Docker uses the internal Docker registry on Minikube’s VM by executing this command:

eval $(minikube docker-env)

Otherwise Docker will use the local registry on your machine, which is not accessible from the VM where minikube is running.

Now, from the Terminal window, execute the docker build command:

docker build -t k8sdemo:v1 .

This will create the image with a name of k8sdemo and a tag of v1, and store it in the Docker registry on the minikube host VM. When deploying the image to Minikube, you’ll reference that tag explicitly.

From the Terminal window execute the kubectl run command:

kubectl run k8sdemo --image=k8sdemo:v1 --port=8080

And now the application is up and running in its own Pod.

Conclusion

In this post I showed you how to work with Kubernetes on your computer. You containerized a simple application, then deployed it to your local Kubernetes cluster.

In Part 5, I’ll show you how to manage an application running in a Kubernetes cluster using kubectl and the Kubernetes Web UI Dashboard.

Want to know more?

If you want to learn more about Kubernetes, check out this post at IBM developerWorks: What is Kubernetes?

Be sure to check out the other posts in this series:

Check out this video at IBM developerWorks TV, where I show you everything I covered in Parts 1-5 of this series:

Introduction to Kubernetes:

Thanks for reading!

–jsp

Container Orchestration with Kubernetes, Part 3

Install Kubernetes on your Computer (Minikube)

Hey everybody! In this post, I’d like to talk about Container-centric infrastructure with Kubernetes. This is Part 3 of a series of posts on using installing and using Kubernetes.

If you missed Part 2 where I give you Kubernetes Overview, make sure to check that out.

In this post, I want to walk you through installing the software you need to run Kubernetes on your computer.

Install the software

You’ll need a few pieces of software to run Kubernetes on your computer:

  • Docker
  • VirtualBox (or some other virtualization software)
  • Node.js
  • Minikube

Install Docker

First, you need Docker. You can find instructions for your platform by clicking this link. If you already have Docker installed, skip to the next section.

Scroll down until you see your platform, which is MacOS in my case, so I’ll click on Docker for MacOS. I want the distribution from the Stable channel, so I click on the link that says Get Docker for Mac (Stable). Always verify the 256 bit SHA checksum of the downloaded file matches what is published.

Now double-click the DMG file to begin the installation, and follow the instructions.

Install VirtualBox

Minikube requires a virtualization environment in order to run. If you want to use software other than VirtualBox, check out the Getting Started with Minikube page at kubernetes.io. If you already have VirtualBox installed, skip to the next section.

To install VirtualBox, go to the VirtualBox installation page, and click on the link that matches your platform. ALWAYS verify the SHA256 checksum matches the downloaded file.

Now double-click the DMG file to begin the installation, and follow the instructions.

Install Node.js

In order to test the demo application, you’ll need Node.js installed. I already have Node.js installed on my Mac, so I’ll skip that for the video. Make sure to check out the Node.js installation page. If you already have Node.js installed, skip to the next section.

Click on the download link that matches your platform, and follow the instructions.

Install Minikube

Go to the Minikube page at GitHub, and look for Installation.

I like to use Homebrew to install software on my Mac. If you’re using Linux or Windows, the Minikube installation page has instructions for those platforms as well.

Drop out to a Terminal window and execute the brew cask install for Minikube:

brew cask install minikube

Homebrew installs Minikube and now it’s ready to go. Yes, it really is that easy (on MacOS anyway).

Conclusion

Now you have all the software you need to work with Kubernetes on your computer. Stay tuned for Part 4, where I’ll show you how to work with Minikube and define an application, deploy it to your local k8s cluster.

Want to know more?

If you want to learn more about Kubernetes, check out this post at IBM developerWorks: What is Kubernetes?

Be sure to check out other posts in this series:

Check out this video at IBM developerWorks TV, where I show you everything I covered in Parts 1-5 of this series:

Introduction to Kubernetes:

Thanks for reading!

–jsp

JUnit Jupiter Annotations: Chapter 1

Overview

In order to run JUnit tests, you need to tell the JUnit Platform about your test classes: which methods are test methods, which methods are part of the test method lifecycle, whether to use extensions, and so on.

You do this through annotations, which are metadata about how to run your tests.

You can download the code from GitHub if you like:

https://github.com/makotogo/HelloJUnit5

In this post, I’ll cover the two annotations you’re likely to use with JUnit, along with examples of each.

@Test

@Test
@DisplayName("When numbers are > 0")
public void testAdd() {
  // Unit test code here
}

Use this annotation to tell the JUnit platform that the method is a test method. This means it will be invoked at the appropriate point in the lifecycle, complete with all the bells and whistles.

Every method you want to run as a test method needs to be annotated with the @Test annotation.

@DisplayName

@DisplayName("Testing using JUnit 5")
public class JUnit5AppTest {
.
.
  @Test   
  @DisplayName("When numbers are > 0")   
  public void testAdd() {     
    // Unit test code here 
  }
.
.
}

By default, the name displayed for a test class or method is the name of the class or method, respectively. The @DisplayName annotation tells JUnit to use the specified name instead.

Check it out: compare the following examples, first without the annotation, then with it. (Both are from the JUnit View in Eclipse)

Without the @DisplayName annotation:

 WithoutDisplayName

And with the @DisplayName annotation:

WithDisplayName

In this simple example, you can see already that the report is cleaner. But when there are several test methods, the value of @DisplayName gets even clearer:

DisplayNameLargerTest

Video

In the video below, I’ll go over the annotations in detail, and you can watch me explain the code as I write it.

Conclusion

In this article, I showed you two of the annotations from the JUnit Jupiter API you’ll definitely want to use. Stay tuned for more in this series, where I’ll show you more annotations from the JUnit Jupiter API.

Be sure to follow along with this series here on my blog, and the accompanying videos on my YouTube channel.

To learn more about the annotations provided by the JUnit Jupiter API visit the JUnit 5 User’s Guide.

Check out my IBM developerWorks JUnit 5 Tutorial Series:

JUnit Jupiter Assertions: Setup

Hey everybody!

The Assertions class of the JUnit Jupiter API is the GO-TO for testing your code. After all, how do you check a condition without an Assertion?

I’m doing a multi-part series on the Assertions API on my YouTube channel (Makoto TV), so make sure and check it out.

In Part 0, I show you how to get the code that accompanies all of the videos, and get your Eclipse workspace setup.

 

Make sure and check it out.

And thanks for reading!

–jsp