CSHARP

unit test c# exception thrown

// fluent syntax
subject.Invoking(y => y.Foo(null))
    .Should().Throw<ArgumentNullException>();

// arrange-act-assert syntax
Action callingFooWithNull = () => subject.Foo(null);

callingFooWithNull.Should().Throw<ArgumentNullException>()
    .WithParameterName("message");

c# unit test for throwing exception method

 [TestMethod]
        public void ShouldThrowExceptionIfDirectorNotExistWhenDeletingDir()
        {
            var folder1 = rootPath + @"unknowfolder";
            Assert.ThrowsException<Exception>(() => Util_Directory.DeleteDirectory(folder1));
        }

c# unit test exception using try catch

  [TestMethod]
        public void FromDirectoryIsnullorEmptyUsingTryCatch()
        {
            try
            {
                var fromDir = "";
                Util_Directory.Copy(fromDir, "", false, false);
            }
            catch (ArgumentException)
            {
                //test successfull here
                return;
            }

            Assert.Fail("Call to Copy method did not fail");
        }