Logging unit test name in Scala

Question

I want to log the unit test names in Scala automatically. The solution with org.junit.rules.TestName works fine in Java, but not in Scala.

Consider the following code snippet:

import org.junit._
import org.junit.rules.TestName

class ScalaUnitTestExample {
    @Rule val testName = new TestName

    @Before def printTestCaseNameBefore() {
        print("\nStart of test case " + testName.getMethodName)
    }

    @After def printTestCaseNameAfter() {
        print("\nEnd of test case " + testName.getMethodName)
    }

    @Test
    def checkAddition() {
        Assert.assertEquals(5, 2 + 3)
    }

    @Test
    def checkMultiplication() {
        Assert.assertEquals(6, 2 * 3)
    }
}

It compiles fine, but when running I receive the following error message:

There was 1 failure:
1) initializationError(ScalaUnitTestExample)
java.lang.Exception: The @Rule 'testName' must be public.
        at org.junit.internal.runners.rules.RuleFieldValidator.addError(RuleFieldValidator.java:90)
        (...)
        at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)

FAILURES!!!
Tests run: 1,  Failures: 1

The Java counterpart works as expected.

I've already tried the following (according to Using JUnit @Rule with ScalaTest (e.g. TemporaryFolder)):

val _testName = new TestName
@Rule def testName = _testName

but this did not really help. In this version the test cases run, but the {testName} results always {null}.

The default access rule in Scala is public, and therefore there is no public keyword. On the other hand, the JUnit framework seems to consider it non-public.

Does anyone know how to overcome this problem? Another similar solution would also be fine! Thank you!

Why don't you use the ScalaTest instead? You'll be able to see the Test name in the logs and there are alternatives for the `@Before` and `@After`. — Zyoma, Mar 22 '16 at 10:59
The issue with the first option is that `val testName` defines both a field and a getter method (in Java terms); the annotation goes to the field by default (but this can be changed: see http://www.scala-lang.org/api/2.11.8/#scala.annotation.meta.package); the field is private (Scala doesn't allow defining non-private fields at all), but JUnit requires it to be public. It's surprising to me that the second option doesn't work. — Alexey Romanov, Mar 22 '16 at 11:23

Jonas Anso · Answer 1 · 2016-03-22T13:12:15.000

1

As you know scala default access rule is public, but scala does a trick, the field is private and it generates getters and setters, and that is the reason @Rule does not work in your code.

You can make it work using

import org.junit._
import org.junit.rules.TestName


    class ScalaUnitTestExample {
      var _testName: TestName = new TestName

      @Rule
      def testName = _testName
      def testName_=(aTestName: TestName) {_testName = aTestName}

      @Before def printTestCaseNameBefore() {
        print("\nStart of test case " + testName.getMethodName)
      }

      @After def printTestCaseNameAfter() {
        print("\nEnd of test case " + testName.getMethodName)
      }

      @Test
      def checkAddition() {
        Assert.assertEquals(5, 2 + 3)
      }

      @Test
      def checkMultiplication() {
        Assert.assertEquals(6, 2 * 3)
      }
    }

Anyway using ScalaTest or Specs2 would make your life easier.

edited Mar 22 '16 at 13:12

answered Mar 22 '16 at 11:12

Jonas Anso

2,057
14
13

Thanks for the hint! Unfortunately your solution results always `null` value. I'll check the other proposals. – Csaba Faragó Mar 22 '16 at 12:27
I do not know what might be the problem. I did run it myself and worked for me. – Jonas Anso Mar 22 '16 at 13:07
Thanks for adding the screenshot! As I see you are using Linux; I have Windows 7. What artifacts versions are you using? My Scala version is 2.11.7, and the JUnit version is 4.9. – Csaba Faragó Mar 22 '16 at 13:47
Clone this repo and run "sbt test" it should work in windows. https://github.com/jonasanso/junit-test-scala – Jonas Anso Mar 22 '16 at 14:25
I did but the result is the same: Start of test case null End of test case null Start of test case null End of test case null[info] Passed: Total 2, Failed 0, Errors 0, Passed 2 [success] Total time: 22 s, completed 2016.03.22. 18:01:52 – Csaba Faragó Mar 22 '16 at 17:05
Thanks for testing, I am sorry I can not help more. Good luck and try out scala test. – Jonas Anso Mar 22 '16 at 22:03
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/107099/discussion-between-csaba-farago-and-jonasanso). – Csaba Faragó Mar 23 '16 at 07:22

score 0 · Accepted Answer · answered Mar 24 '16 at 15:15

Solution (with a light hack): put the method name logic into a base class written in Java. Java source (UnitTestBase.java):

import org.junit.*;
import org.junit.rules.TestName;

public class UnitTestBase {
    @Rule public TestName testName = new TestName();

    @Before public void printTestCaseNameBefore() {
        System.out.println("Start of test case " + testName.getMethodName());
    }

    @After public void printTestCaseNameAfter() {
        System.out.println("End of test case " + testName.getMethodName());
    }
}

Scala source (ScalaUnitTestExample.scala):

import org.junit._

class ScalaUnitTestExample extends UnitTestBase {
    @Test
    def checkAddition() {
        Assert.assertEquals(5, 2 + 3)
    }

    @Test
    def checkMultiplication() {
        Assert.assertEquals(6, 2 * 3)
    }
}

Compile:

scalac -cp .;junit-4.9.jar UnitTestBase.java ScalaUnitTestExample.scala

Run:

scala -cp .;junit-4.9.jar org.junit.runner.JUnitCore ScalaUnitTestExample

Result:

JUnit version 4.9
.Start of test case checkMultiplication
End of test case checkMultiplication
.Start of test case checkAddition
End of test case checkAddition

Time: 0,005

OK (2 tests)

score 0 · Answer 3 · answered Jan 15 '19 at 15:23

0

Use JUnit 4.12, I used @Jonas Anso's solution and it worked with that version, it did not work in 4.8 and 4.10. We have to set @Rule on a method, not on a field, seems that is ignored in 4.8 and 4.10. Also only getter is needed.

answered Jan 15 '19 at 15:23

user10439725

129
7

Logging unit test name in Scala

3 Answers3