ExpectedException in nUnit gave me an error

40
votes

I'm new to using Testing Tools on the .NET Framework, so I downloaded it from NuGet with help from ReSharper.

I am using this Quick Start to learn how to use nUnit. I had just copied the code and an error came up on this attribute:

[ExpectedException(typeof(InsufficientFundsException))] //it is user defined Exception

The error is:

The type or namespace name 'ExpectedException' could not be found (are you missing a using directive or an assembly reference?)

Why? And if I need such functionality, what should I replace it with?

3
c#.netunit-testingtestingnunit
What error is being displayed? Is the error being shown within nUnit or your IDE? – Chawin
I think your code return an exception which is not the InsufficientFundsException – Nikson K John

3 Answers

72
votes

If you're using NUnit 3.0, then your error is because the ExpectedExceptionAttribute has been removed. You should instead use a construct like the Throws Constraint.

For example, the tutorial you linked has this test:

[Test]
[ExpectedException(typeof(InsufficientFundsException))]
public void TransferWithInsufficientFunds()
{
    Account source = new Account();
    source.Deposit(200m);

    Account destination = new Account();
    destination.Deposit(150m);

    source.TransferFunds(destination, 300m);
}

To change this to work under NUnit 3.0, change it to the following:

[Test]
public void TransferWithInsufficientFunds()
{
    Account source = new Account();
    source.Deposit(200m);

    Account destination = new Account();
    destination.Deposit(150m);

    Assert.That(() => source.TransferFunds(destination, 300m), 
                Throws.TypeOf<InsufficientFundsException>());
}
14
votes

Not sure if this changed recently but with NUnit 3.4.0 it provides Assert.Throws<T>.

[Test] 
public void TransferWithInsufficientFunds() {
    Account source = new Account();
    source.Deposit(200m);

    Account destination = new Account();
    destination.Deposit(150m);

    Assert.Throws<InsufficientFundsException>(() => source.TransferFunds(destination, 300m)); 
}
6
votes

If you still want to use Attributes, consider this:

[TestCase(null, typeof(ArgumentNullException))]
[TestCase("this is invalid", typeof(ArgumentException))]
public void SomeMethod_With_Invalid_Argument(string arg, Type expectedException)
{
    Assert.Throws(expectedException, () => SomeMethod(arg));
}