Unit test behavior after exception selected?

Question

I am just starting with unit testing and have a script. I am not sure how to evaluate, and my decision does not seem to be correct.

I have some code that does something if it fails, that is, it throws an exception, the exception gets caught and is logged as shown below.

 public T CreateTypedObjectInstance<T>()
 {
     T o = default(T);
     try
     {
         o = Activator.CreateInstance<T>();
     }
     catch (Exception ex)
     {
         LogError(ex);
         throw ex;
     }
     return o;
 }

 private void LogError(Exception ex)
 {
     if (logger != null)
     {
        logger.LogError(ex);
     }
 }

I want to check that on error, the LogError () method is called, which in turn calls another object.

I approached this using the mock for the logger and catching the first exception, and then I approved the LogError method. However, this does not seem right to catch an exception? I remember reading something bad to try and catch in tests? Is there any other way to run this test or should I reorganize the logic? Any ideas would be great!

      [Test]
    public void CreateTypedObjectInstance_GivenTypeWithoutPrivateContructor_LogErrorToLogger()
    {
        //Setup Method used
        MockRepository mockery = new MockRepository();
        ILogger mockedLogger = mockery.StrictMock<ILogger>();
        genericObjectFactoryInstance.Logger = mockedLogger;
        Expect.Call( delegate { mockedLogger.LogError(null); } ).IgnoreArguments();
        mockery.ReplayAll();
        // this will throw an error as String does not have a parameterless constructor
        try
        {
            genericObjectFactoryInstance.CreateTypedObjectInstance<String>();
        }
        catch { /*ignore this error to test behaviour after*/ }
        mockery.VerifyAll();
    }

EDIT

Mark Rushakoff , .

        [Test]
    public void CreateTypedObjectInstance_GivenTypeWithoutPrivateContructor_LogErrorToLogger()
    {
        //Setup Method used
        MockRepository mockery = new MockRepository();
        ILogger mockedLogger = mockery.StrictMock<ILogger>();
        genericObjectFactoryInstance.Logger = mockedLogger;
        Expect.Call( delegate { mockedLogger.LogError(null); } ).IgnoreArguments();
        mockery.ReplayAll();
        Assert.Throws<MissingMethodException>(() => genericObjectFactoryInstance.CreateTypedObjectInstance<String>());
        mockery.VerifyAll();
    }

Answer 1

, NUnit , Assert.Throws.

Assert.Throws<YourCustomException>(() => GenericObjectFactoryInstance.CreateTypedObjectInstance<String>());

@Bruno answer , .

Answer 2

unit test , . :

:

public int getCalc(int a, int b) throws SampleException {
   if (a > b) {
      throw new SampleException();
   }
   // (..)
}

:

public void testGetCalcException() {

   try {
     getCalc(2,1); // 2 > 1  exception is expected
     fail("SampleException was expected but was not thrown");       

   } catch(SampleException e) {
      // great - test passed!
   } 

}

Answer 3

NUnit ut, ExpectedException, , . , .

. ExpectedException