01-example.md

Example Assignment

The goal of this assignment is to familiarize yourself with the infrastructure and tools used in this class. Even though the grade in this assignment won't influence your grade for the course, it is important that you work through this assignment carefully.

Part 1: Obtaining the Project Files

First, make sure you've followed the Tools Setup page.

At this point, we strongly encourage you to take the time to read at least the first three chapters of the Git Book. If you just copy-paste the commands we give you without understanding them, it's likely that you'll make a mistake somewhere and waste time. Git can be a huge productivity enhancer when used correctly, so it's definitely worth the investment!

We'll starting by cloning the repository containing all our assignment (make sure to replace GASPAR with your EPFL username (the one with letters, not the one with number) in the following command).

git clone -b example git@gitlab.epfl.ch:lamp/student-repositories-f19/cs210-GASPAR.git cs210-example

cd cs210-example

Now that we've obtained the project, let's take a look at its structure:

.
├── build.sbt
├── project
│   ├── ...
└── src
    ├── main
    │   └── scala
    │       └── example
    │           └── Lists.scala
    └── test
        └── scala
            └── example
                └── ListsSuite.scala

• All the files ending with .sbt or in the project/ directory are build tool configuration files: you don't need to modify them or look at them for any of the assignments
• The project sources are in src/main/scala/
• The sources of the unit tests are in src/test/scala/. You will need to make all the tests pass to complete the assignments, and you should write additional tests to check for cases that our tests do not cover.

Part 2: Using sbt

Start sbt by running:

sbt

Once it's finished starting (this may take a while), you'll be able to enter sbt commands. You can compile your project using compile and run the tests with test (this automatically compiles your code if needed to). Note that if compilation fails, no tests will be run. The first time you'll run test in an assignment you should see many errors: that's normal, your job is to make the tests pass! To do this, it's useful to understand in details what the test output means, here's an example:

This tells us several things:

• There's a test named max of a few numbers (10pts) in the class ListsSuite in the package example
• The test failed with an exception: scala.NotImplementedError: an implementation is missing. This is followed by a stack trace showing where the exception happened.
• This exception was thrown from the method scala.Predef$.??? in the file Predef.scala at line 284.
• This method was called from example.Lists$.max in the file Lists.scala at line 40.
• ... which was itself called from the method example.ListsSuite.max of a few numbers in the file ListsSuite.scala at line 83.

It's now time to look at some code: the next section will show you how to start and navigate using the IDE.

Part 3: Using the IDE