FluentAssertions Throw() not listed to use

user_9468024 0
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I'm using FluentAssertions with NUnit and I realize that the method Throw() and other related methods is not listed for me to use. Do I have to install any other package to have access to this method?

I'm using the last release, 5.4.2, installed by NuGet.

fluent-assertions nunit c#
1 Answers

The documentation doesn't make it very clear, but Should().Throw() has to be applied to an Action (or, as pointed out by @ArturKrajewski in a comment below, a Func and also async calls):

Action test = () => throw new InvalidOperationException();
test.Should().Throw<InvalidOperationException>();

So the tests could look like this:

public class AssertThrows_ExampleTests {
    [Test]
    public void Should_Throw_Action() {
        var classToTest = new TestClass();

        // Action for sync call
        Action action = () => classToTest.MethodToTest();
        action.Should().Throw<InvalidOperationException>();
    }

    [Test]
    public void Should_Throw_Action_Async() {
        var classToTest = new TestClass();

        // Func<Task> required here for async call
        Func<Task> func = async () => await classToTest.MethodToTestAsync();
        func.Should().Throw<InvalidOperationException>();
    }

    private class TestClass {
        public void MethodToTest() {
            throw new InvalidOperationException();
        }

        public async Task MethodToTestAsync() {
            throw new InvalidOperationException();
        }
    }
}
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