Getting started with scala-cli

Question
1

Following a discussion in another thread, I’ve decided to give scala-cli a try, and I’m experimenting with moving an existing sbt project to scala-cli. I’ve been struggling with one thing: What’s the equivalent of sbt’s Test/runMain? I currently use it to start a customized Scalatest runner (to grade students’ work), and I’d rather not have to change my workflow too much.

EDIT

Here’s my workaround so far:

java -cp $(scala-cli compile --test . -p) Grade

It kind of works, but shows some downloading messages with every run:

Downloading https://repo1.maven.org/maven2/com/github/charpov/tiny-scala-utils-test_3/
Downloading https://charpov.github.io/TinyScalaUtils/maven/com/github/charpov/tiny-scala-utils-test_3/
Downloaded https://charpov.github.io/TinyScalaUtils/maven/com/github/charpov/tiny-scala-utils-test_3/
Downloaded https://repo1.maven.org/maven2/com/github/charpov/tiny-scala-utils-test_3/
Downloading https://charpov.github.io/TinyScalaUtils/maven/com/github/charpov/tiny-scala-utils_3/
Downloading https://repo1.maven.org/maven2/com/github/charpov/tiny-scala-utils_3/
Downloaded https://charpov.github.io/TinyScalaUtils/maven/com/github/charpov/tiny-scala-utils_3/
Downloaded https://repo1.maven.org/maven2/com/github/charpov/tiny-scala-utils_3/

I’m using two small files for a test:

Run.scala:

//> using repository "https://charpov.github.io/TinyScalaUtils/maven/"
//> using dep com.github.charpov::tiny-scala-utils:1.1.1
//> using test.dep com.github.charpov::tiny-scala-utils-test:1.1.1
//> using scala 3.3

@main def Run(): Unit = tinyscalautils.text.info()

Grade.test.scala:

@main def Grade(): Unit = println("100/100")
1 Like
2

It doesn’t look like there is a command that works, however, if you are using Metals in VS Code then a main method in a file in the test scope should still get the run | debug buttons above the method, this isn’t something you can do from the command line which is annoying I know.

Edit: I’ve now opened an issue for this There is no command to run a main method in test scope · Issue #2728 · VirtusLab/scala-cli · GitHub

3 Likes
3

I write grading tests with Scalatest (using a few extensions to assign weights and timeouts to tests) and I run them through a simple runner that adds points and produces a final grade. I obviously rely on scripts to run an entire course assignment (and we’re discussing a tool with CLI in its name :wink: ) .

Thanks for starting the issue. It feels like something that shouldn’t be too hard to implement (there’s already a way to specify a “test” scope for compile, so why not for run?)

Do you know why starting java with the full class path triggers these downloading messages?

4

Is this relevant? Migrating from the old Scala runner | Scala CLI

5

I never used the old runner. I usually don’t even bother installing it on my machines and let sbt handle everything.

6

It’s not directly related to your question, but I’ve migrated some project from sbt to scala-cli and, using vscode + metals, I’ve found that compilation, execution times are much longer.

Is your experience similar?

Thanks.

7

Not my experience, I also migrated a mid-size project (about 500 source files) from sbt to scala-cli and compilation times are equal or slightly faster. I guess it depends on the size and libraries of the project; maybe sbt has better parallel compilation or something?

8

Thanks !! I’ll test it more thoroughly.