在诸如JUnit和TestNG的测试框架中，测试执行侦听器的典型用例是什么？

Question

JUnit,TestNG, and Spring testing have test execution listeners as an extension mechanism. Test execution listeners seem to be a low level feature of interest to framework developers and tool developers.

What are the main use cases in which Test execution listeners are useful? Can they be useful to application developers?

Answer 1

In Case of testng the listners are the most remarkable thing for me. The testNg listners allows me to simplyfy the test method content and manage each test with server startup , user registration, populating artifacts need for tests . And also clear up the environment for each test cycle.

At the each listener level im performing following operations so i don't have to bother about them in side my tests

IExecutionListener

   - onExecutionStart()
         Emma instrumentations
         Server start 
  - onExecutionFinish()
         Server Sutdown
         Emma report generation

• ISuiteListener Set environment properties ex- Key Store Paths

    Populate Users. 

• ITestListener

  • On Start

      Artifact Deployment 

  • On Finish

      Artifact Clean up 

• IReporter

• Generate TestNg Report, Generate sure-fire report, Export data for Dashboard

Answer 2

For JUnit, the listeners are designed to be a method of reporting, and are used like this internally. So, you can display counts of tests executed, success, failure, error, that sort of thing. This is used externally as well, such as in maven-surefire . See JUnit4RunListener.java as an example.

Another use would be to output in a different format, such as XML. I think the main use cases for the other frameworks are the same.

In JUnit, the listener class is not meant to be used in the manner that Dharshana uses his test listeners in testng, that is as a setup/teardown. The objects used in the Listeners ( Description , Failure , Result ) are immutable and don't encourage direct access to the test class itself. I'm not sure about TestNG, Cedric would be a better person to ask about that.

Are they useful for an application developers? They may well be, depending upon how your tests are set up. They would only be used in the context of tests, so if they can improve them, then go ahead, use them. One use case would be JUnit test report enrichment with JavaDoc , see my answer . To recap the answer, if the developers add a test for a specific bug, then they can add an annotation to that test linking it back to the bug. There is a custom RunListener, which collects all of the information in the annotations together and produces a report for the final customer.