Debugging ScalaTest tests in NetBeans with the Maven ScalaTest Plugin

In the spirit of creating blog posts whenever there is something important that I've figured out and I should not lose or forget, here I go.

A month or two ago, we moved all of our Java tests at Apprenda to run using the Maven Scalatest plugin . We have been using ScalaTest from day one; however, for a while there we were using SureFire + @RunWith + JUnitRunner annotations to kick off the tests. However, since IntelliJ was quite happy to run ScalaTest tests without anything else (e.g. like the @RunWith and JUnitRunner annotations), we would sometimes end up in a situation where we have some tests that are created during development in the IDE; however, when the build is run using just plain Maven, it would skip over these tests.

So, the as described in the ScalaTest documentation on working w/ the plugin , you first disable the surefire plugin, and then add the ScalaTest Maven plugin to run the tests. That all worked great, and now all of our tests run, regardless of whether we remembered to add the @RunWith annotation.

That presented a problem for me : when we were running the tests with SureFire, NetBeans was more than happy to run and debug the tests. However, when we switched to the Maven ScalaTest plugin - no such luck .. what do to ? I'm totally fine with not seeing the graphical test runner results that NetBeans shows w/ JUnit Tests ; however, where it becomes a problem is when I can't run or debug the individual tests from the IDE. The tests run just fine when you "Test" the whole project (e.g. right click on the project and choose "Test" from the context menu), but if you try to run an individual test (e.g. right click on a test case and choose Test from the context menu), or when you're inside the test case go to the Run -> Test File menu you're out of luck, nothing shows up.

So, getting the single test to run from NetBeans turns out to be pretty simple :
1. In the Project Properties -> Actions panel, choose the "Test File" action, change the properties from "test=${packageClassName}" to "suites=${packageClassName}" . As indicated in the ScalaTest documentation, the way to tell ScalaTest what test to run is using the suites system property, e.g. :

So, that's great, but how do you debug the test ? Looking at the ScalaTest documentation I was a bit confused on how to do this, as there were a few options related to debugging, but which ones to set in order to get this from NetBeans, it wasn't entirely clear.

It turns out the fix was fairly simple :
1. Since by default NetBeans runs surefire:test to run individual tests, the goal that is run needed to be switched to just "test" - this allows the Maven Scalatest plugin to run (as it binds to the test phase and does nothing for surefire:test)
2. I had to add  a couple of additional system properties that ScalaTest needs in order to run the right test, turn on debugging, and connect the NetBeans debugger and the ScalaTest test that is running.

#This teslls scalatest to run the test with this class
suites=${packageClassName}

#These tell ScalaTest to start the new process with debugging enabled
logForkedProcessCommand=true
debugForkedProcess=true
debugArgLine=-Xdebug -Xrunjdwp:transport=dt_socket,server=n,address=${jpda.address}

# This tells netbeans to fire up the debugger and wait for a connection
jpda.listen=true

Here's an example of what it looks like :

Tada - enjoy being able to run and debug individual ScalaTest tests right from NetBeans !

Intro to Programming : Drawing a House

What is this 

To help everyone along in getting started with drawing the Minecraft Creeper, I asked my son to put together a program that draws a house. It uses a lot of similar elements to the Creeper that the students need to draw, and might show a few new things that we didn't cover in class yet.

The Code

   
  clear()
  println("setAnimationDelay() sets how fast the turtle speed is, invisible makes the turtle invisible but the line is still there")
  println("penUp() make the line disapear but the turtle doesn't, setFillColor(Color(0, 0 ,0)) and setPencolor(Color(0, 0, 0,))  changes the color")
  println("repeat(){ } makes the program repeat as many time as you want")
  setAnimationDelay(100)
  invisible()
  penUp()
  left()
  forward(150)
  setFillColor(Color(255, 0, 51))
  setPenColor(Color(255, 0, 51))
  penDown()
  right()
  //makes the square for the house, note the usage of 'repeat'
  repeat(4){
    forward(150)
    right()
  }
  forward(150)
  //this makes the roof
  setFillColor(Color(51, 51, 0))
  setPenColor(Color(51, 51, 0))
  right(60)
  forward(90)
  right(60)
  forward(90)
  penUp()
  //this makes the windows
  setFillColor(Color(51, 153, 255))
  setPenColor(Color(51, 153, 255))
  right(60)
  forward(40)
  right()
  forward(20)
  penDown()
  forward(30)
  right()
  forward(30)
  right()
  forward(30)
  right()
  right()
  penUp()
  forward(80)
  penDown()
  forward(30)
  left()
  forward(30)
  left()
  forward(30)
  left()
  forward(30)
  left()
  penUp()
  left()
  forward(80)
  penDown()
  //this makes the door
  setPenColor(Color(153, 68, 0))
  setFillColor(Color(153, 68, 0))
  forward(60)
  left()
  forward(35)
  left()
  forward(60)
  left()

The Outcome

The finished product looks something like this 

Intro to Programming : The First Class

.. And so it begins... 

This spring, I am teaching an "Intro to Programming" class at the After School Enrichment program at Craig Elementary, so this blog will get some new content with the progress of the class.

The First Class

In the first class, we covered quite a lot of ground : we learned quite a bit about each other, what the students in the class were interested in. As expected, most kids do enjoy video games, like learning how things work, and just plain enjoy working with computers. We briefly chatted about why people program in the first place : to express themselves, to tackle new challenges, and to be able to harness the power of computers for their own inventions.

We covered some of the basic concepts of what a program is : a sequence of instructions that follow some specific grammar rules (just like they do in English). We had a quick introduction to Kojo (our programming environment, more on that later) and the various elements of Kojo's user interface - the command / script area, the drawing area, the menus, the output / error message area. Most importantly, we focused on how to continue learning from the environment - using code completion / prompts to see the syntax of commands that we hadn't used before, reading the command documentation. We also spent some time learning to recover from failure, when something unexpected happens - resetting the zoom level on the drawing area (if one accidentally zoomed out too far), and just bringing up the right windows if one of them suddenly disappeared.

Our first programming exercise really didn't involve a computer : I asked my students to "program me" and command me from one side of the room to the other, while avoiding the obstacles along the way - chairs, large metal poles, backpacks. I did attempt to behave like a computer - I just followed the instructions that were given to me and failed a few times along the way - ran into an office chair, gonked my head against the metal pole. In order to tie up with what came next (which was drawing a square in our programming environment), I then asked the kids to use the same commands that they used to guide me through the room, but this time, to make me walk in a square along the tiled floor using the same limited set of commands - e.g. left, right, forward, back.


So, with the basic commands under our belt, the kids got to programming. We learned how to draw a square. First everyone came up with a short program for a square, and then we experimented with variations on the topic - some of the kids really enjoyed drawing BIG squares and seeing the turtle in action while it was drawing the squares. Then, for the more ambitious students, we tried drawing a triangle (and yes, this is where the geometry skills came shining through - what were the angles in an equilateral triangle, you ask :-) ). The example looks something like this :

The takeaway : for the kids who want a little challenge at home, I asked them to practice drawing a Minecraft Creeper, which very roughly, looks like this - it will give the kids a chance to practice some of the skills that they've already picked up (e.g. drawing squares), but also give a chance to learn a few new things as well (using background and fill colors)

Setting up Kojo

Kojo is a very kid-friendly piece of software which was created specifically to help children learn about programming and have fun along the way. It should run on all modern OS-s (Windows, Linux, MacOS), so as long as you have a desktop computer to install this on (but it will not work on a tablet), your child should be able to continue exploring it on their own. It contains a rich library of examples written in Kojo (which we will lean on in the class) - it even has a game or two that the kids can play with.

Setting up Kojo is pretty straighforward:
1. Dowload Kojo from http://www.kogics.net/kojo-download
2. Run the downloaded .jar file (e.g. by right clicking and choosing "Run" on windows), it will launch the installer - just follow through the installer and you should have an icon on your desktop that you can use to launch the software.