For start a test with xunit we create a class with the name of MathTests for testing our Math class in our production code. Assert. This is the first part of my posts about using Testing .Net Core Code with XUnit and its features for testing code, these posts series cover all parts of xunit in detail. if the result is the same as our expected value the test will pass otherwise it will fail. The accepted parameter for this method is the same as previous ones. xUnit.net is a free, open source, community-focused unit testing tool for the .NET Framework. The first assertion is Assert.Raises, it verifies that a event with the exact event args is raised. Finally it accepts another delegate that execute the action. We can see how much more readable this way of assertion is. Know more about xUnit Here . Object. 1. the test project has a reference to our production project for testing classes in our production project and also we install XUnit library on our TestProject with Nuget, and now we can write XUnit based test class in our test project. also, we verify our actual object is exactly the same type of PersonModel or one of its derivatives with this code Assert.IsAssignableFrom(okObjectResultAssert?.Value) because of ObjectResult.Value is of type object and object is one of the PersonModel derivatives. The Assert.Throws ensures that the code throws that exact exception while Assert.DoesNotThrow ensures the code does not throw any exceptions. xUnit aka xUnit.net is a unit testing framework for the .NET. Hi, I'm Hamid Mosalla, I'm a software developer, indie cinema fan and a classical music aficionado. Success! The xUnit.net Assert Class Normally, the very last line in a unit test method is an assertion that something is true or false. There are some assertion methods that can be used to check to see if a property changed on an object. xUnit.net is a free, open source, community-focused unit testing tool for the .NET Framework. for example, we have a method let’s call it GetOddNumbers and takes a limit value input as a parameter and returns odd numbers from zero up to this limit value. we have also a compliment method for assert null value, Assert.NotNull(object actualObject) method verifies that our object is not null reference. for Assert.Same it checks objects have the same reference and Assert.NotSame method checks our objects don’t have the same reference. Let’s consider this class as an example. It is most commonly used in two circumstances: As an Unfinished Test Assertion (page X) when a test is first identified and implemented as an nearly empty Test Method. A pattern I've encountered quite a few times when unit testing recently is to assure an event is raised as the direct cause of some action. If we want to compare two string with ignoring case options we can use Assert.Equal(string expectedString, string actualString,bool ignoreCase) , for example, in the above example we can write this code Assert.Equal(“morning”, result, true) method for check our result is equal to expected value without case sensitivity and our test will pass because case sensitivity is not important. It is open-source and completely free to use. I will be using xunit test framework to write unit tests, it uses Fact for a single test and Theory with (InlineData) to test multiple conditions in a single test. In my previous post, we saw how value and type based assertions works in xUnit. Here I write about my experiences mostly related to web development and .Net. xunit is xunit core package and  xunit.runner.visualstudio the package allows to visual studio test explorer to be able to discover tests and execute our tests. This principle applies for all kinds of tests, be it writing Integration Tests or Unit Tests. We also saw how to check for situations when an exception is thrown. The most commonly used Single Outcome Assertion is fail which causes a test to be treated as a failure. in bellow sample, we want to test our person domain class so we create a test for IsActive property that we named it, in our test we prepare our test with initializing our SUT (person domain class), now for verifying our domain class raise IsActiveChanged event correctly before acting we should subscribe to the event, so when IsActive property raises the event we will be notified. Testing event handlers in XUnit can be done through the Assert.Raises method. Then in the test method you can use its expect() and expectMessage() to assert the type of expected exception and the exception message. Great! What happens when a method doesn’t return a value, or update some property? Those that check a type and its reference. Originally authored by Dennis Doomen, but … suppose we have some C# production code which is in our production project and we have some test classes in our TestProject for testing our production code. An essential part of every UI test framework is the usage of a unit testing framework. I'm Mehdi, a full-stack developer with +8 years of experience in different Microsoft Tech stacks with an interest in Microservices and Cloud Architecture, DDD, Event Sourcing, Clean Architecture. In my next post we’re going through the third type of assertions. The Assert.RaisesAny verifies that an event with the exact or a derived event args is raised. Like xUnit's way of testing exceptions with Assert.Throws, it's simple to test exceptions, but we must be mindful of the flow of the try/catch logic within our test methods. Published with Ghost. unittest - Automated testing framework. This is a generic method that takes a type parameter the type of exception we want to check for. xunit has a method to do this Assert.Raises(Action> codeToattach, Action> codeTodettach, Action testCode) which in this method T is our expected event args when event raises and we need to provide some arguments, the first argument is an action which attaches to the event, here in our sample we use a lambda expression … Our test project also needs to access our XunitSamples project and its classes so we can right-click on our test project and add a reference to our sample project. we can also use the .Net CLI to add our test project to our solution so for doing this we first go to root project that our solution file exist there and use dotnet sln add XUnitSamples.Tests\XUnitSamples.Tests.csproj command to add our test project to the solution. The same pattern is repeated in many other languages, including C, Perl, Java, and Smalltalk. Assert.That(t, Is.InstanceOf()) if t : S and T : S as the type of Assert.That(T,IMatcher) wont allow the mismatches. If we see our project references, we can see it automatically added Nuget packages for XUnit to our projects that these packages: xunit , xunit.runner.visualstudio as you can see in the below csproj file. a more specific way of testing a collection is to test the number of items in this collection so we can use this Assert.Equal(3 , result.Count()) method, it is a little more specific. we also can use .Net CLI to create a XUnit Test project for this purpose in our root folder our application we can use dotnet new xunit -n XUnitSamples.Tests -o XUnitSamples.Tests command to create XUnit Test project, you can see help for xunit with this command dotnet new xunit -h. now we need our test project has a reference to our sample project so we use dotnet add reference ../XUnitSamples/XUnitSamples.csproj  command to add a reference to the sample project. If during a test execution thrown an error our test will fail, but for more confidence in our code, we can check that our code throws the exceptions at correct times for this purpose xunit provides an assertion method Assert.Throws(Action testCode) or Assert.Throws(Func testCode) that will catch the exception and assert the type of our exception. Here are the examples of the csharp api class Xunit.Assert.IsType(System.Type, object) taken from open source projects. Use StackOverflow for general questions, go on Slack to contact the team directly, or visit Github for issues & feature requests. Written by the original inventor of NUnit v2, xUnit.net is the latest technology for unit testing C#, F#, VB.NET, and other .NET languages. Get the latest posts delivered right to your inbox. Thismakes it easier to manage both the class library and the unit test project.Inside the solution directory, create a MathServicedirectory. This was the first part of using XUnit in .Net Core Series, in the next post we’ll talk about other features of xunit. In this section we’re going to see some assertions based on their type. Dot Net University © 2020 I write some tests for this method here. 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. One of the most popular ones in the .NET world is MSTest.However, you cannot find a single place where you can get started with its syntax. there is a way for a cleaner and easier assertion of collection for checking for existing some specific values in the collection or our total collection is as expected with this Assert.Equal(IEnumerable expectedCollection, IEnumerable actualCollection) and an example of this in our code is Assert.Equal(new[] { 1, 3, 5 }, result). Finally Assert.Ra… We can also check two object references are equal that means two objects point to the same reference in the memory, xunit has two methods for this purpose, Assert.NotSame(object expectedObject, actualObject) and Assert.Same(object expectedObject, actualObject). One of most general way to write assertion for collection is checking our collection is not empty with this Assert.NotEmpty(IEnumerable actualCollection) method that verifies a collection is not empty, it is very general and we don’t care about specific values in our collection but we just wanna make sure there is something in our collection so for this case we can use this method. We can also use Record.Exception by passing the action in to see if it throws specific exception. In this example, we call GetTimeOfDay method on our SUT and we passed 7 as TimeSpan value to our method then compare the result with our Expected value that in this case is “Morning”, If the result will be the same test will pass otherwise it will fail.in xunit we have also some other assert methods for evaluating results with expected value such as Assert.StartsWith(string expectedStartWith,string actualString) and Assert.EndsWith(string expectEdendWith,string actualString). Finally the ones that inspect an action and the things that happened around this action.   •   Instead, the Assert.Throws construct is used. If we have Inheritance hierarchies in our application some times we need to check some hierarchy level for a specific type and some times we want to check the exact object type, for these purposes xunit provides two assertion methods, Assert.IsType(object actualObject) method that evaluates our object under the test is exactly the same as a given type specified in the generic type of IsType method, not a derived type we also have a compliment of this method Assert.IsNotType(object actualObject). Here I will use approach described in Richard Banks' post Stop Using Assert.Throws in Your BDD Unit Tests… The test passes if the expected exception … By voting up you can indicate which examples are most useful and appropriate. we named this method to Add_WhenCalled_ReturnSumOfInputs that “Add” is the name of the method we calling on SUT (method on the test) so method on the test is “Add” and “WhenCalled” is what scenario we test here, in this code, we use this term for our purpose our scenario and last section “ReturnSumOfInputs” says add method when called, it should “ReturnSumOfInputs” actually it is our expected behavior. The first method uses Assert.Throws, it verifies that the exact exception is thrown (and not a derived exception type). the generic type of T in this method is the exact not derived expected  exceptions type to be thrown, In the case where you want to also allow derived exceptions, the Assert.ThrowsAny(Action testCode) method can be used and the method parameter takes an Action or Func delegate that should cause this exception to be thrown below code is a sample of an exception asserting: In this sample, if we pass zero as an input parameter for the second argument we expect our system under test method throw an DividByZeroException , so in this situation, our test should pass and if an DividByZeroException is not thrown when our system under test method is called the test will fail. In other word we pass a series of actions  into the assert to check to see if elements of the collection are as expected. 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