This attribute is used to test whether an expected exception is thrown. The test method will pass if the expected exception is thrown. The test will fail if the thrown exception inherits from the expected exception.

If a test has both an ExpectedException attribute and an Assert statement, either one can cause the test to fail. To determine whether the attribute or the statement caused the test to fail, double-click the test result to open the Results Details page for the test. For more information about test results, see Test Results Reported.

This attribute can be specified on a method. There can be only one instance of this attribute on a method.

For more information about how to use attributes, see Extending Metadata Using Attributes.

The following class contains the method to test:

Public Class DivisionClass
   Public Function Divide(ByVal numerator As Integer, ByVal denominator As Integer) As Integer
      Return numerator \ denominator
   End Function
End Class

The following test method tests the Divide method of the DivisionClass object. It tests for the existence of a DivideByZeroException.

Imports Microsoft.VisualStudio.TestTools.UnitTesting
Imports MyVBProject

<TestClass()> _
Public Class DivisionClassTest
    <TestMethod()> _
    <<b>ExpectedException</b>(GetType(System.DivideByZeroException), "MyMessage")> _
    Public Sub DivideTest()
        Dim target As DivisionClass = New DivisionClass
        Dim numerator As Integer = 4
        Dim denominator As Integer = 0
        Dim actual As Integer
        actual = target.Divide(numerator, denominator)
    End Sub
End Class