scala-js/scala-js

Scala.js, the Scala to JavaScript compiler

Andrzej Sołtysik

@asoltysik

Is there a way to run tests when exporting the project as ESModule? Im getting

Could not run test MainSpec: org.scalajs.testcommon.RPCCore$RPCException: scala.scalajs.js.JavaScriptException: TypeError: Cannot read property 'MainSpec' of undefined

. I stumbled upon this thread: https://www.reddit.com/r/scala/comments/c84rae/unit_testing_in_scalajs/ but the solutions proposed there don't change anything for me

version is 0.6.28

Sébastien Doeraene

@sjrd

The post at https://www.reddit.com/r/scala/comments/c84rae/unit_testing_in_scalajs/eskcrtc?utm_source=share&utm_medium=web2x should be enough to get things running.

The settings will have to be in the .settings() (resp. .jsSettings()) of the relevant project (resp. crossProject)

Andrzej Sołtysik

@asoltysik

that's what I did, will try that again though

Øyvind Raddum Berg

@oyvindberg

@marcgrue I managed to run and debug my shared tests in the end in intellij. Somehow it works when running all tests in package, as opposed to running a single test. This was with utest.

Andrzej Sołtysik

@asoltysik

@sjrd it worked when i upgraded scalatest from 3.0.5 to 3.0.8

Adam Fraser

@adamgfraser

Hi. I'm trying to set global.process.exitcode to a non-zero value and then allow my program to exit gracefully. I am expecting to exit with a failure in that case but I am still exiting with a success. I have confirmed that I am using the node.js environment. Am I doing something wrong?

Frank P. Tominc

@franktominc

Hey guys, I'm having a weird behavior here. I'm trying to pass command-line arguments to a scalajs script and for some reason it doesn't work. What am I missing here?

@JSExportAll
@JSExportTopLevel("Main")
object Main {
  def main(args: Array[String]): Unit = {
    println("abc")
    args.foreach(println)
  }
}

node my-script-opt.js 3123 12312 12312312 3123123 12321312 1231231 12312312 123123
abc

aappddeevv

@aappddeevv

I think you need to use the process.argv value to access them.

Sébastien Doeraene

@sjrd

@franktominc The args of def main are always an empty array in Scala.js. The existence of the parameter is only there for reasonable compatibility with Scala/JVM. As @aappddeevv said, use Node.js' process.argv value to read command-line arguments.

Frank P. Tominc

@franktominc

Oh, so I need a MainJS and a MainJVM?

Sébastien Doeraene

@sjrd

Ah, yes, I'm afraid so.

Frank P. Tominc

@franktominc

Well, that is a bummer. What would be the impact of passing process.argv as args in the compiler? Is there a reason for that not being the standard behavior?

Sébastien Doeraene

@sjrd

The reason is that Scala.js is independent of Node.js. Passing process.argv would fail in other JS environments. Scala.js does not take sides.

aappddeevv

@aappddeevv

Don't forget that node has the node bin and then the script name so val args = process.argv.drop(2) to access the first arg. I typically have a separate project with 2-3 lines in it representing "main" and handling some major "context" instance specific to the environment. Same on the JVM side.

Frank P. Tominc

@franktominc

@aappddeevv can you share a minimal project with me, please?

Frank P. Tominc

@franktominc

Well, I got something working here.


@JSExportAll
@JSExportTopLevel("Main")
object Main {

  def test(s: Array[String]): Unit = {
    println("ABC")
    s.foreach(println)
  }
}

var main = require("./test.js");

main.Main.test(process.argv);

It prints the ABC but on the foreach it's giving me a TypeError: Cannot read property 'length' of undefined. I'm using .jsSettings(scalaJSLinkerConfig ~= { _.withModuleKind(ModuleKind.CommonJSModule) }) and calling it using:

node myScript.js 123 123 123

Any ideas?

Sébastien Doeraene

@sjrd

A JS array is not a valid Array[String], so you're running into undefined behavior. But it should have thrown an UndefinedBehaviorError. Unless you're testing in fullOpt mode?

aappddeevv

@aappddeevv

outdated and unfinished minimal project notes: https://aappddeevv.gitbooks.io/scalajs-nodejs-cli-applications/content/cliscala.html

Sébastien Doeraene

@sjrd

You need to export a method that takes a js.Array[String], if you want to go the exports route.

aappddeevv

@aappddeevv

If you are just trying to access the args, use a nodejs facade, or define your own.

Frank P. Tominc

@franktominc

Oh, I'm using the fullOpt mode

Sébastien Doeraene

@sjrd

You should only use the fullOpt mode when you're happy with your testing and you want to deploy/run for real.

fullOpt is not suited for iterative development: it does not check undefined behavior, and takes way longer to compile.

Frank P. Tominc

@franktominc

I made a little parser for arithmetic expressions and I want to run some tests to convince my boss that the java result and the scalaJs result are the same(I'm using BigDecimals)

I am trying to write something minimal, so I can generate a lot of test cases, call the jar file, call the JS file and compare both outputs

aappddeevv

@aappddeevv

You may just want to setup tests, say, with scalatest and demonstrate the sameness by running the tests.

Frank P. Tominc

@franktominc

Yeah, but how can I run scalatests against the JS file?

Sébastien Doeraene

@sjrd

With theProjectJS/test. Exact same thing than theProjectJVM/test for running the tests on the JVM.

Marc Grue

@marcgrue

^
@oyvindberg and @jhegedus42 - Alright, I can test/debug shared files in IntelliJ by right-clicking the jvm package and choose Run or Debug. Thanks for your help and input. This is good enough for now. I'll probably file a bug report with IntelliJ that you can't do the same by right-clicking the individual shared files directly.

aappddeevv

@aappddeevv

With tests, you can skip the "main" issue. An if you are new to scala/sbt, you could just write the JVM version, run it. Then copy the entire project to a new directory, add the scala-js plugin and %%% to the scalatest dependency. Then run the test in that new dir the same way.

Frank P. Tominc

@franktominc

Build.properties

sbt.version = 1.2.8

Plugins.sbt

addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "0.6.1")
addSbtPlugin("org.scala-js" % "sbt-scalajs" % "0.6.28")

build.sbt

import sbtcrossproject.CrossPlugin.autoImport.crossProject

val sharedSettings = Seq(
  name := "arithmetic-interpreter",
  version := "0.1.0-SNAPSHOT",
  libraryDependencies += "com.lihaoyi" %%% "fastparse" % "2.1.3"
)

lazy val arithmeticInterpreter = crossProject(JSPlatform, JVMPlatform)
    .in(file("."))
    .settings(sharedSettings)

Project Structure
https://imgur.com/dlJsydi

When I do a publishLocal and try to run it I'm running into a ClassNotFoundException, so somehow it's not getting the scalalib and packaging together with my jar, any idea why?

Exception in thread "main" java.lang.NoClassDefFoundError: scala/collection/mutable/ArrayOps$ofRef
    at Main$.main(Main.scala:6)
    at Main.main(Main.scala)
Caused by: java.lang.ClassNotFoundException: scala.collection.mutable.ArrayOps$ofRef
    at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:349)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 2 more

Tried to call using java -cp <scalalib> -jar <myjar> and java -jar <myjar>

Sébastien Doeraene

@sjrd

Why not run from sbt with arithmeticInterpreterJVM/run?

Victor Ivri

@vivri

Hi, what's the best way to declare an imported function that accepts an object as an arg? will it be js.Object, js.Dictionary[???] or something else?

^ specifically, here's the function I'd like to import: https://github.com/katzer/cordova-plugin-background-mode#override-defaults

Antoine Doeraene

@sherpal

@vivri you can define a trait NotificationOptions extends js.Object where you set the members that you can set being js.UndefOr[T] for T the type you need. For example val title: js.UndefOr[String] = js.undefined.
Then, when you write the facade for that function, you ask def setDefaults(options: NotificationOptions): Unit = js.native. And you can feed the argument by instantiated new instances of NotificationOptions (a method apply in the companion object is not a bad idea in general)

Victor Ivri

@vivri

Great, thank you @sherpal !

Victor Ivri

@vivri

I wonder if it makes sense to convert the UndefOr[T] to Option[T]? Or will it erase the distinction between undefined and null...

Antoine Doeraene

@sherpal

I think the problem is that Option[T] is not a js object

Victor Ivri

@vivri

I meant on the level of Scala.js API design

aappddeevv

@aappddeevv

I always thought that I should keep Option throughout my code but then I realized that for data coming from an API that is already marked as js.UndefOr, it was easier just to start using js.UndefOr for data that is always intended for a JS API. I defined an extensive amount of js.UndefOr, A|Null, js.Any, js.Object, Null, truthy and Option converters to switch between them as needed. Alot of js doc is subtly wrong about what they accept/don't accept.

Victor Ivri

@vivri

@aappddeevv these converters look like prime candidates for a companion lib :-D

Alot of js doc is subtly wrong about what they accept/don't accept.

agree!

aappddeevv

@aappddeevv

Yeah....I did define one as well as kept them part of the project. Here's the version embedded in one of my repos. The lib version is published elsewhere.

aappddeevv

@aappddeevv

I especially like when the docs say the value will be undefined, comes in as null though, and I have to use a value.toNonNullOption because the scalajslib .toOption does not check for the null as it follows scala semantics (so you can inadvertently get a Some(null)). You either wind up always using .filter or my hideous .toNonNullOption or .truthyOption, or, you model it as a UndefOr[A|Null], ...

Øyvind Raddum Berg

@oyvindberg

I've wanted a js.NullableOrUndefinedOr (with a shorter name) for a very long time too

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