scala / nanotest-strawman

Scala Verify is a minimal testing framework for Scala. Trust, but verify.

Version Matrix


Verify is a minimalist unit testing framework, tracing its origins to Minitest + Expecty + SourceCode.

It is a small testing framework cross-compiled for Scala 2.11, 2.12, 2.13, Scala 3.x, Scala.js 0.6 and 1.0, and Scala Native 0.3.x and 0.4.0.

Usage in sbt

For build.sbt (use the %%% operator for Scala.js or Scala Native):

// use the %%% operator for Scala.js or Scala Native
libraryDependencies += "com.eed3si9n.verify" %% "verify" % "1.0.0" % Test

testFrameworks += new TestFramework("verify.runner.Framework")



Test suites MUST BE objects, not classes. To create a test suite without setup and teardown, extend BasicTestSuite trait:

Here's a simple test:

import verify._

object SomethingTest extends BasicTestSuite {
  test("addition") {
    assert(2 == 1 + 1)

  test("failing test") {
    case class Person(name: String = "Fred", age: Int = 42) {
      def say(words: String*) = words.mkString(" ")
    assert(Person().say("ping", "poing") == "pong pong")

  test("should throw") {
    class DummyException extends RuntimeException("DUMMY")
    def test(): String = throw new DummyException

    intercept[DummyException] {

In the context of BasicTestSuite, assert(...) function is wired up to power assertion, as known in Groovy. In the above, the failing test would result to the following:

- failing test *** FAILED ***
  assertion failed

  assert(Person().say("ping", "poing") == "pong pong")
         |        |                    |
         |        ping poing           false


For the most part, assert(...) should do the job.

To compare large strings, scala-verify also provides assertEquals(expected: String, found: String, message: => String). In case of an error, it will print the diff in color for easier detection of the differences.

setup and tearDown

In case you want to setup an environment for each test example and need setup and tearDown semantics, per test example, extend TestSuite. Then on each test definition, you'll receive a fresh value:

import verify.TestSuite

object SomethingTest extends TestSuite[Int] {
  def setup(): Int = {
    Random.nextInt(100) + 1

  def tearDown(env: Int): Unit = {
    assert(env > 0, "should still be positive")

  test("should be positive") { env =>
    assert(env > 0, "positive test")

  test("should be lower or equal to 100") { env =>
    assert(env <= 100, s"$env > 100")

Some tests require setup and tear down logic to happen only once per test suite being executed and TestSuite supports that as well, but note you should abstain from doing this unless you really need it, since the per test semantics are much saner:

object SomethingTest extends TestSuite[Int] {
  private var system: ActorSystem = _

  override def setupSuite(): Unit = {
    system = ActorSystem.create()

  override def tearDownSuite(): Unit = {
    system = null

asynchronous testing

scala-verify supports asynchronous results in tests, use testAsync and return a Future[Unit]:


object SomethingTest extends BasicTestSuite {
  testAsync("asynchronous execution") {
    val future = Future(100).map(_+1)

    for (result <- future) yield {
      assert(result == 101)

That's all you need to know.

Historical background

Verify started out as an attempt to create a cross-platform, zero-dependency, minimal, testing framework for bootstrapping the toolchain and a small handful of foundational third-party libraries. See


All code in this repository is licensed under the Apache License, Version 2.0. See NOTICE.