Has unit/integration test without asserts right to exist?

Question

Recently I had to chance to see a bunch of tests without any assert. Those tests had to be accuracy tests.

I think the only thing that can be tested with such tests is to check if none exceptions are raised during execution flow. But anyway I really don't understand how we can verify the accuracy of the code with no asserting tests - even the methods that do nothing can pass such tests.

So I'm wondering what can be purpose of such tests and what else can be tested with that?

Answer 1

I'd let them have the right to exist if they are testing some "legacy code" - code that no one really has a good grip on. No, if they are in there to put on a show of "high code coverage".

It's a first step to getting some confidence in the code. The invisible check is :"no exceptions are thrown". However once you've wrapped up the app in some smoke tests like these, the next step would be to turn the implicit check into an explicit check - put on your thinking cap and come up with observable changes that you can assert from your tests.
You can use tools like TestLint to catch tests like these.

Answer 2

Here is an example (C#, NUnit):

[Test]
public void StartUpShutDownDoesntThrow() {
   var aService = new Service();
   aService.StartUp();
   aService.ShutDown();
}

If this test passes it ensures the following:

• The constructor doesn't throw an exception
• Startup() doesn't throw an exception
• ShutDown() doesn't throw an exception

All three items are valuable, maybe even epic. You woud be surprised how many commercial application don't even have something as basic as this as part of their QA process.

So, yes, tests without asserts can have their value, too.