CODEWITHSUNDEEP
unit-testingcoding-stylemstest
Bruce Li
Bruce Li

Reputation: 515

What's the best way to avoid try...catch...finally... in my unit tests?

I'm writing many unit tests in VS 2010 with Microsoft Test. In each test class I have many test methods similar to below:

[TestMethod]
public void This_is_a_Test()
{
  try
  {
    // do some test here
    // assert
  }
  catch (Exception ex)
  {
    // test failed, log error message in my log file and make the test fail
  }
  finally
  {
    // do some cleanup with different parameters
  }
}

When each test method looks like this I fell it's kind of ugly. But so far I haven't found a good solution to make my test code more clean, especially the cleanup code in the finally block. Could someone here give me some advices on this?

Thanks in advance.

Upvotes: 6

Views: 4018

Answers (3)

sll
sll

Reputation: 62484

If you really want to handle and log exceptions whilst test execution you can wrap up this standard template in a helper method and use like shown below [*].

But if exceptions is a part of test case this is wrong approach and you should use facilities provided by a test framework, for instance NUnit provides such helpers to test exceptions:

Assert.Throws<ExceptionType>(() => { ... code block... });
Assert.DoesNotThrow(() => { ... code block... });

And to do cleanup special method attributes like [TestCleanup] and [TestInitialize] to do test initialization and cleanup automatically by a test framework.

[*] The idea is to wrap test body in a delegate and pass into the helper which actually perform test execution wrapped in the try/catch block:

// helper
public void ExecuteTest(Action test)
{
  try
  {
     test.Invoke();
  }
  catch (Exception ex)
  {
    // test failed, log error message in my log file and make the test fail
  }
  finally
  {
    // do some cleanup with different parameters
  }
}

[TestMethod]
public void This_is_a_Test_1()
{
   Action test = () =>
   {
       // test case logic
       // asserts
   };

   this.ExecuteTest(test);
}

Upvotes: 6

user1046334
user1046334

Reputation:

Clear all try-catch-finally (especially catch is not only unnecessary, but even harmful, you should not catch exception when testing) and do the cleanup in tearDown method (however is it done in MS Test, I would presume there will be something like [TearDownMethod] or [FixtureTearDown] or something like that).

Upvotes: 1

Valamas
Valamas

Reputation: 24719

Have you considered using the ExpectedException attribute on the test method? http://msdn.microsoft.com/en-us/library/microsoft.visualstudio.testtools.unittesting.expectedexceptionattribute.aspx

Upvotes: 0

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