I need some way to execute code before/after each test. This code should be the same for all tests and test cases globally. I was hoping I could use RunListener, but it seems that I need to alter all the tests (or their parent class) to specify custom test runner or use JUnitCore for it to work.
Is there any way I can register this listener without affecting the code base? (there are many many tests and I would need to alter a lot of them for the listener to work)
I believe you could use a JUnit Rule feature for it. I assume that all your tests extend some basic test class. So you could add the Rule there.
I think you'll need to implement a custom rule. Quick googling reveals a pretty good tutorial.
Related
Is there any way to use a rule to add additional tests? For example, I would like to convert the Theories runner to a rule, but I haven't been able to find a way to make Rules add additional tests.
I'm in the middle of setting up PMD as a tool in our team to support us writing better code. Basically I'm building Ant scripts and try to set up some rules for everyone to use.
But right now I hit this problem:
When I write JUnit tests I don't want to use the same rules I apply on our main source code. I don't care that much about String rules (like string dupliates or weird instantiations) in the junit tests.
My questions is:
Is that a fault on my side and should I start writing better JUnit tests?
Should I provide a 2nd set of rules that disables some of the string/design/finalizers rules?
The second option - I don't run PMD against my tests at all. I could and PMD provides some JUnit specific rules. I would definitely use a separate ruleset against the test code though. I expect more String literals and some thing specified instead of using conditionals/loops. After all, I don't want to duplicate the code I am trying to test.
Two things. Why are you trying to set up rules why not using the existing rules? (Special requirements?). And second yes of course Unit tests should have a good quality as well. Your Unit test test you production code so shouldn't they have at least the same quality as your production code?
I want to test validation logic in a legacy class. The class uses a method to load effective dates from a config file.
I have written a subclass of the class in question and overridden the config method so I can run my unit test against the subclass with any combination of effective dates.
Is this an appropriate strategy? It strikes me as a clean technique for testing code that you don't want to mess with.
I like it, its the most simple and straight forward way to get this done. And since it is a legacy class, it will not change anymore, so you don't run danger of bumping into the fragile base class problem neither.
It seems to be an appropriate strategy to me. Ofcourse with this override you won't
be able to test the code (in the original class) that loads the config data, but if you have other tests to cover this sceario then I think the approach you outlined is fine.
I'm trying to migrate to JUnit 4 and I'm not clear about the correct way to set up test suites.
I know how to set up a test suite with fixed tests using the #SuitesClasses annotation.
However, I want to have a top-level suite class, where I can programatically decide which test classes or suites I want to load. I know that there are addTest and addTestSuite operations in the TestSuite class.
However, if I define a TestSuite subclass with a constructor that attempts to add these tests and try to run it, I get an error "Must have SuiteClasses annotation".
Any idea how to do this?
I would recommend creating a subclass of the BlockJUnit4ClassRunner and pull in the classes you want to test manually. The protected methods of the class do all the hard work for you, although you might want to tweak the Descriptions a bit to make sure the results are all unique in the output files.
I often find myself changing my code to make it more testable, I always wonder whether this is a good idea or not. Some of the things I find myself doing are:
Adding setters just so I can set an internal object to a mock.
Adding getters for internal maps/lists so I can check the internal state of the object has changed after performing some external action.
Wrapping concrete system classes and creating a new interface so I can mock them. For example, File classes can be hard to mock - so I'll create a new interface FileInterface and WrappedFile which extends it and then use the FileInterface instead of File.
Changing your code to make it more testable can be a good thing, but only if it makes your code itself better. Refactoring for testability can make your code better independent of the test suite's needs. Those are good changes.
Of your three examples only #3 is a really good one; often those new interfaces will make your code more flexible for regular use later. #1 is usually addressed for testing via dependency injection, which in my mind makes code needlessly more complicated but does at least make it easier to test. #2 sounds like a bad idea in general.
It is perfectly fine and even recommended to change your code to make it more testable. Here is a list of 10 things that make code hard to test.
I think your third is really ok, but I'm not too fond of the first and the second. If you just open your class internals with getters and setters, then you're giving up encapsulation completely. Depending on your language, there are ways to open visibility of some parameters to test. But what I actually do (which opens encapsulation a little less) is to make the fields I want to check protected (when dependency injection doesn't solve the problem).
Then, on the test project, I inherit the class, and create a "more powerful one", where I can check the internals, but I change nothing on the implementation, and use this class in the tests.
Finally, changing your code to have dependency injection and inversion of control is also highly recommended, as it makes your code easier to test AND more readable and maintainable.
Though changing is ok, the best things to do is to TDD. It produces testable code naturally, once the tests are written first.
It's a trade-off..
You want a slim, streamlined API or a bloated more complicated, but easilier tested one.
Not the answer you wanted to hear, I know :)
Seems reasonable. Some things don't need checking though; I'd suggest checking to see if adding to a list worked is a little useless. But do whatever you feel comfortable with.
Ideally, every class you design should test itself, so you don't need to change the public interface. But you are talking about legacy code, so I think that changing code is reasonable only when the public impact isn't much noticeable. I would prefer to add a static inner class to test instead of bloat the interface of the tested class.