Getting started with TestNG and ScalaTest

If you want to write TestNG tests in Scala that you run with TestNG, you can enjoy more concise code by using ScalaTest's assertions and/or matchers. To use assertions, mix org.scalatest.Assertions into your test class:

import org.scalatest.Assertions
import scala.collection.mutable.ListBuffer
import org.testng.Assert._
import org.testng.annotations.Test
import org.testng.annotations.Configuration

class ExampleSuite extends Assertions {

  var sb: StringBuilder = _
  var lb: ListBuffer[String] = _

  @Configuration { val beforeTestMethod = true }
  def initialize() {
    sb = new StringBuilder("ScalaTest is ")
    lb = new ListBuffer[String]
  }

  @Test def verifyEasy() { // Uses TestNG-style assertions
    sb.append("easy!")
    assertEquals("ScalaTest is easy!", sb.toString)
    assertTrue(lb.isEmpty)
    lb += "sweet"
    try {
      "verbose".charAt(-1)
      fail()
    }
    catch {
      case e: StringIndexOutOfBoundsException => // Expected
    }
  }

  @Test def verifyFun() { // Uses ScalaTest assertions
    sb.append("fun!")
    assert(sb.toString === "ScalaTest is fun!")
    assert(lb.isEmpty)
    lb += "sweeter"
    intercept[StringIndexOutOfBoundsException] {
      "concise".charAt(-1)
    }
  }
}

You can see the difference in conciseness between the TestNG assertions used by verifyEasy and the ScalaTest assertions used by verifyFun. If you compile this class with the Scala compiler, TestNG will happily run the resulting class file. Here's how you compile it:

scalac -cp scalatest-1.0.jar:testng-5.7-jdk15.jar ExampleSuite.scala

Here's one way to run it using TestNG:

$ scala -cp .:scalatest-1.0.jar:testng-5.7-jdk15.jar org.testng.TestNG -testclass ExampleSuite
[Parser] Running:
  Command line suite


===============================================
Command line suite
Total tests run: 2, Failures: 0, Skips: 0
===============================================

If you wish to give yourself the option of running with either TestNG or ScalaTest, mix in org.scalatest.testng.TestNGSuite. Trait TestNGSuite already mixes in Assertions:

import org.scalatest.testng.TestNGSuite
import scala.collection.mutable.ListBuffer
import org.testng.Assert._
import org.testng.annotations.Test
import org.testng.annotations.Configuration

class ExampleSuite extends TestNGSuite {

  var sb: StringBuilder = _
  var lb: ListBuffer[String] = _

  @Configuration { val beforeTestMethod = true }
  def initialize() {
    sb = new StringBuilder("ScalaTest is ")
    lb = new ListBuffer[String]
  }

  @Test def verifyEasy() { // Uses TestNG-style assertions
    sb.append("easy!")
    assertEquals("ScalaTest is easy!", sb.toString)
    assertTrue(lb.isEmpty)
    lb += "sweet"
    try {
      "verbose".charAt(-1)
      fail()
    }
    catch {
      case e: StringIndexOutOfBoundsException => // Expected
    }
  }

  @Test def verifyFun() { // Uses ScalaTest assertions
    sb.append("fun!")
    assert(sb.toString === "ScalaTest is fun!")
    assert(lb.isEmpty)
    lb += "sweeter"
    intercept[StringIndexOutOfBoundsException] {
      "concise".charAt(-1)
    }
  }
}

Because ExampleSuite is still a valid TestNG test class, it can still be run with TestNG:

$ scala -cp .:scalatest-1.0.jar:testng-5.7-jdk15.jar org.testng.TestNG -testclass ExampleSuite
[Parser] Running:
  Command line suite


===============================================
Command line suite
Total tests run: 2, Failures: 0, Skips: 0
===============================================

But because it is also a ScalaTest Suite, you can now also run it with ScalaTest:

$ scala -cp scalatest-1.0.jar:testng-5.7-jdk15.jar org.scalatest.tools.Runner -p . -o -s ExampleSuite
Run starting. Expected test count is: 2
Suite Starting - ExampleSuite
[Parser] Running:
  Command line suite

Suite Starting - ExampleSuite
Test Starting - ExampleSuite: verifyEasy
Test Succeeded - ExampleSuite: verifyEasy
Test Starting - ExampleSuite: verifyFun
Test Succeeded - ExampleSuite: verifyFun
Suite Completed - ExampleSuite

===============================================
Command line suite
Total tests run: 2, Failures: 0, Skips: 0
===============================================

Suite Completed - ExampleSuite
Run completed in 315 milliseconds.
Total number of tests run: 2
Suites: completed 2, aborted 0
Tests: succeeded 2, failed 0, ignored 0, pending 0
All tests passed.

One final variation you may wish to try is to use ScalaTest's matchers DSL. Simply mix in ShouldMatchers (or MustMatchers if you prefer "must" to "should"). Here's an example:

import org.scalatest.testng.TestNGSuite
import org.scalatest.matchers.ShouldMatchers
import scala.collection.mutable.ListBuffer
import org.testng.Assert._
import org.testng.annotations.Test
import org.testng.annotations.Configuration

class ExampleSuite extends TestNGSuite with ShouldMatchers {

  var sb: StringBuilder = _
  var lb: ListBuffer[String] = _

  @Configuration { val beforeTestMethod = true }
  def initialize() {
    sb = new StringBuilder("ScalaTest is ")
    lb = new ListBuffer[String]
  }

  @Test def verifyEasy() { // Uses ScalaTest assertions
    sb.append("easy!")
    assert(sb.toString === "ScalaTest is easy!")
    assert(lb.isEmpty)
    lb += "sweet"
    intercept[StringIndexOutOfBoundsException] {
      "concise".charAt(-1)
    }
  }

  @Test def verifyFun() { // Uses ScalaTest matchers
    sb.append("fun!")
    sb.toString should be ("ScalaTest is fun!")
    lb should be ('empty)
    lb += "sweet"
    evaluating { "concise".charAt(-1) } should produce [StringIndexOutOfBoundsException]
  }
}

As before, you can run this class with either JUnit or ScalaTest:

$ scala -cp .:scalatest-1.0.jar:testng-5.7-jdk15.jar org.testng.TestNG -testclass ExampleSuite
[Parser] Running:
  Command line suite


===============================================
Command line suite
Total tests run: 2, Failures: 0, Skips: 0
===============================================

$ scala -cp scalatest-1.0.jar:testng-5.7-jdk15.jar org.scalatest.tools.Runner -p . -o -s ExampleSuite
Run starting. Expected test count is: 2
Suite Starting - ExampleSuite
[Parser] Running:
  Command line suite

Suite Starting - ExampleSuite
Test Starting - ExampleSuite: verifyEasy
Test Succeeded - ExampleSuite: verifyEasy
Test Starting - ExampleSuite: verifyFun
Test Succeeded - ExampleSuite: verifyFun
Suite Completed - ExampleSuite

===============================================
Command line suite
Total tests run: 2, Failures: 0, Skips: 0
===============================================

Suite Completed - ExampleSuite
Run completed in 315 milliseconds.
Total number of tests run: 2
Suites: completed 2, aborted 0
Tests: succeeded 2, failed 0, ignored 0, pending 0
All tests passed.