Scala Native comes with JUnit support out of the box. This means that you can write JUnit tests, in the same way you would do for a Java project.

To enable JUnit support, add the following lines to your build.sbt file:


If you want to get more detailed output from the JUnit runtime, also include the following line:

testOptions += Tests.Argument(TestFrameworks.JUnit, "-a", "-s", "-v")

Then, add your tests, for example in the src/test/scala/ directory:

import org.junit.Assert._
import org.junit.Test

class MyTest {
  @Test def superComplicatedTest(): Unit = {
    assertTrue("this assertion should pass", true)

Finally, run the tests in sbt by running test to run all tests. You may also use testOnly to run a particular test, for example:

testOnly MyTest
testOnly MyTest.superComplicatedTest

Testing with debug metadata

Debug builds with enabled debug metadata allows to produce stack traces containing source positions, however, to obtain them runtime needs to parse the produced debug metadata. This operation is performed when generating stack traces for the first time and can take more than 1 second. This behavior can influence tests expecting to finish within some fixed amount of time. To mitigate this issue set the environment variable SCALANATIVE_TEST_PREFETCH_DEBUG_INFO=1 to ensure that debug info would be loaded before starting test execution.

Debugging sygnals

In case of problems with unexpected signals crashing the test (SIGSEGV, SIGBUS) you can set the environment variable SCALANATIVE_TEST_DEBUG_SIGNALS=1 to enable debug signal handlers in the test runner. When enabled test runner would set up signal handlers printing stack trace for most of the available signals for a given platform.

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