public void TestMethod() { string myString = "hello"; Aver.IsNotNull(myString); // this will pass string nullString = null; Aver.IsNotNull(nullString); // this will fail and throw an exception }In the above example, we are testing the Aver.IsNotNull method by passing a non-null string and a null string. The first assertion passes, but the second assertion fails and throws an exception. Overall, FluentAssertions is a useful package for developers who want to write clean and maintainable unit tests in C#.