Parameterized Unit Tests in Scala (with JUnit4)

Question

Is there a way to implement a parameterized unit test with Scala? Currently I use JUnit4 in the rest of my programs and I would like to continue using only "standard" APIs.

I found an example for Junit4 with Groovy, but I have problems defining the static parts. Could be, because I am also quite new with Scala :-)

I am currently as fas as

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

import org.junit.runner.RunWith
import org.junit.runners.Parameterized
import org.junit.runners.Parameterized.Parameters

@RunWith(classOf[Parameterized])
class MyTest extends junit.framework.TestCase {

    @Parameters object data {
        ...
    }

    @Parameter ...

    @Test
    def testFunction() = {
    }

Horst Dehmer Horst Dehmer · Accepted Answer · 2011-01-08T12:22:39

That's quite a nuisance, but it works. Two important things I discovered: companion object must come after test class, the function returning the parameters must return a collection of arrays of AnyRef (or Object). arrays of Any won't work. That the reason I use java.lang.Integer instead of Scala's Int.

import java.{util => ju, lang => jl}
import org.junit.Test
import org.junit.runner.RunWith
import org.junit.runners.Parameterized
import org.junit.runners.Parameterized.Parameters

@RunWith(value = classOf[Parameterized])
class JUnit4ParameterizedTest(number: jl.Integer) {
    @Test def pushTest = println("number: " + number)
}

// NOTE: Defined AFTER companion class to prevent:
// Class com.openmip.drm.JUnit4ParameterizedTest has no public
// constructor TestCase(String name) or TestCase()
object JUnit4ParameterizedTest {

    // NOTE: Must return collection of Array[AnyRef] (NOT Array[Any]).
    @Parameters def parameters: ju.Collection[Array[jl.Integer]] = {
        val list = new ju.ArrayList[Array[jl.Integer]]()
        (1 to 10).foreach(n => list.add(Array(n)))
        list
    }
}

The output should be as expected:

Process finished with exit code 0
number: 1
number: 2
number: 3
number: 4
number: 5
number: 6
number: 7
number: 8
number: 9
number: 10

Parameterized Unit Tests in Scala (with JUnit4)

2 Answers