This build will always fail because it has 2 examples of failing tests: one because of a defect in the SUT (system under test), and one because of an error in the test itself.

Learning objectives

• Simple hello world example
• Experience with Git source code management
• Building with SBT
• Automated unit testing with JUnit
• Continuous integration with GitHub Actions

System requirements

• Java 17 SDK or later (Java 17 LTS release recommended)
• SBT

Running the application

Without command-line arguments:

$ sbt run

With specific command-line arguments:

$ sbt "run arg1 arg2 arg3"

Running the tests

$ sbt test

Generating the test coverage reports

$ sbt jacoco

If the tests pass, you will then see the coverage report on the console. In addition, you can view a formatted HTML version of report in a web browser.

If the tests don't pass, however, you should force the generation of the test coverage report:

$ sbt jacocoReport

In Gitpod, navigate to and open

target/scala-2.12/jacoco/report/html/index.html

then press the "show preview" button in the top right corner.

On macOS:

$ open target/scala-2.12/jacoco/report/html/index.html

On Linux:

$ xdg-open target/scala-2.12/jacoco/report/html/index.html

On Windows: please let me know if you know how to do this from the WSL command line. Otherwise you can open the index file in your web browser.

Note that the report will show 0% coverage as long as there are failing tests.

Running the application outside SBT

This allows passing command-line arguments directly:

On Linux or macOS:

$ sbt stage
$ ./target/universal/stage/bin/hello-java arg1 arg2 arg3

On Windows:

> sbt stage
> .\target\universal\stage\bin\hello-java arg1 arg2 arg3