In this section we will discuss how to test Scala.js code managed as Full cross project. All names for example subproject name such as fooJVM are taken from cross compile example.

Directory Structure

<project root>
 +- jvm
 |   +- src/main/scala
 |   +- src/test/scala
 +- js
 |   +- src/main/scala
 |   +- src/test/scala
 +- shared
     +- src/main/scala
     +- src/test/scala

Similarly to {shared|js|jvm}/src/main/scala folders that contain your code, there can be also {shared|js|jvm}/src/test/scala folders that would contain your tests. Tests that verify correctness of shared code should go to shared test folder, while tests that check Scala JVM code or Scala.js code only should go to jvm or js test folders respectively. Calling sbt> fooJVM/test will execute all tests residing in shared and jvm folders, thus testing Scala JVM code. Calling sbt> fooJS/test will execute all tests residing in shared and js folders, so Scala.js code is tested. In case of the full cross project, root project aggregates JVM and JS parts, so when calling sbt> test will effectively run both fooJVM/test and fooJS/test.

Integration testing

Configuring a regular non-Scala.js sbt project to have it:test is a well described task, see documentation for more details. In a CrossProject it won’t work out-of-the-box because of 2 reasons. First reason is that by default Scala JVM and Scala.js it configurations won’t be aware of shared/src/it/scala folder. Second is that Scala.js it configuration by default does not contain ScalaJSClassLoader definition required for running Scala.js tests. To fix that you need to add the following settings to the crossProject definition along with IntegrationTest settings:

lazy val cross = crossProject.in(file(".")).
  // adding the `it` configuration
  // adding `it` tasks
  // add `shared` folder to `jvm` source directories
  jvmSettings(unmanagedSourceDirectories in IntegrationTest ++=
    CrossType.Full.sharedSrcDir(baseDirectory.value, "it").toSeq).
  // add `shared` folder to `js` source directories
  jsSettings(unmanagedSourceDirectories in IntegrationTest ++=
    CrossType.Full.sharedSrcDir(baseDirectory.value, "it").toSeq).
  // adding ScalaJSClassLoader to `js` configuration

Now you can put tests in {shared|jvm|js}/src/it/scala and they will run when you call sbt> it:test. Similarly to test, there is also two iterations and they can be executed separately by explicitely stating jvm or js project name, for example sbt> fooJS/it:test.

Testing frameworks

A list of testing frameworks compatible with Scala.js can be found here.

Note: Don’t forget to mark a test framework SBT dependency as test,it if you have both unit and integration tests.