You’ll end up with an AggregateException every time. A very extensive set of extension methods that allow you to more naturally specify the expected outcome of a TDD or BDD-style unit tests. That’s the exception type returned from async methods; it wraps the actual exception. XUnit – Part 3: Action Based Assertions Assert.Raises and Assert.Throws In my previous post , we saw how value and type based assertions works in xUnit. JUnit 4. When using this method the generic type parameter indicates the type of expected exception and the method parameter takes an action that should cause this exception to be thrown, for example: I have been using xUnit for a couple of years now. Hot Network Questions Why do Hilton Garden Inns have color printers guests can use freely, … You're supposed to await the result (see xunit's acceptance tests). Assert in XUnit. The ExpectedException object is created as a rule that expects none exception is thrown so this rule doesn’t affect all existing test methods: @Rule public ExpectedException exception = ExpectedException.none(); Then in the test method you can use its expect() and expectMessage() to assert the type of expected exception and the exception message. I still miss the DoesNotThrow method from NUnit for one reason: explicity. Test for Exceptions using xUnit's Assert.Throws xUnit kindly provides a nice way of capturing exceptions within our tests with Assert.Throws. The assertion library is optional in 2.x, so if you don't like our assertions, you can remove the xunit.assert NuGet package, and use one of the plethora of third party assertion libraries. Sometimes our code contains a certain path where an exception is thrown. Reading tests has to be easy, and having a DoesNotThrow in the assertion part of the tests tells us what the result should be, or not be. Assert.Equal(2, answer);} Testing for Thrown Exception. When using JUnit 4, we can simply use the expected attribute of the @Test annotation to declare that we expect an exception to be thrown anywhere in the annotated test method. All we need to do is supply Assert.Throws with an exception type, and an Action that is supposed to throw an exception. xUnit Assert.Throws and Record.Exception does not catch exception. Forcing the tests using .Result doesn’t work so great when you want to test for a certain type of exception to be thrown. 3. Assert.Throws returns the exception that's thrown which lets you assert on the exception.. var ex = Assert.Throws(() => user.MakeUserActive()); Assert.That(ex.Message, Is.EqualTo("Actual exception message")); So if no exception is thrown, or an exception of the wrong type is thrown, the first Assert.Throws assertion will fail. [Fact] public async Task Test1() { await Assert.ThrowsAsync(() => MethodThatThrows()); } In this specific degenerate case, you could just return the Task that Assert.ThrowsAsync yields without using await, but the key thing is you need to hand the resulting Task back to the xUnit framework, i.e. In this post I’m going to focus on assertions that check whether or not something happened. The assertThrows() method enables more fine-grained control for exception assertion logic because we can use it around specific parts of the code. Example Targets .NET Framework 4.5 and 4.7, .NET Core 2.0 and 2.1, as well as .NET Standard 1.3, 1.6, 2.0 and 2.1. An assertion is a boolean expression at a specific point in a program which will be true unless there is a bug in the program. Call a utility method to evaluate whether an expected outcome has been achieved. 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