XElementAssertionSpecs.cs

using System;
using System.Xml.Linq;
using FluentAssertions.Execution;
using Xunit;
using Xunit.Sdk;

namespace FluentAssertions.Specs.Xml
{
    public class XElementAssertionSpecs
    {
        #region Be / NotBe

        [Fact]
        public void When_asserting_an_xml_element_is_equal_to_the_same_xml_element_it_should_succeed()
        {
            // Arrange
            var theElement = new XElement("element");
            var sameElement = new XElement("element");

            // Act
            Action act = () =>
                theElement.Should().Be(sameElement);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_an_xml_element_is_equal_to_a_different_xml_element_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = new XElement("element");
            var otherElement = new XElement("other");

            // Act
            Action act = () =>
                theElement.Should().Be(otherElement, "because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement to be*other*because we want to test the failure message, but found *element*");
        }

        [Fact]
        public void When_asserting_an_xml_element_is_equal_to_an_xml_element_with_a_deep_difference_it_should_fail()
        {
            // Arrange
            var theElement =
                new XElement("parent",
                    new XElement("child",
                        new XElement("grandChild2")));
            var expected =
                new XElement("parent",
                    new XElement("child",
                        new XElement("grandChild")));

            // Act
            Action act = () => theElement.Should().Be(expected);

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement to be <parent>…</parent>, but found <parent>…</parent>.");
        }

        [Fact]
        public void When_the_expected_element_is_null_it_fails()
        {
            // Arrange
            XElement theElement = null;

            // Act
            Action act = () =>
                theElement.Should().Be(new XElement("other"), "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>()
                .WithMessage("Expected theElement to be <other /> *failure message*, but found <null>.");
        }

        [Fact]
        public void When_element_is_expected_to_equal_null_it_fails()
        {
            // Arrange
            XElement theElement = new XElement("element");

            // Act
            Action act = () => theElement.Should().Be(null, "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>()
                .WithMessage("Expected theElement to be <null> *failure message*, but found <element />.");
        }

        [Fact]
        public void When_both_subject_and_expected_are_null_it_succeeds()
        {
            // Arrange
            XElement theElement = null;

            // Act
            Action act = () => theElement.Should().Be(null);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_an_xml_element_is_not_equal_to_a_different_xml_element_it_should_succeed()
        {
            // Arrange
            var element = new XElement("element");
            var otherElement = new XElement("other");

            // Act
            Action act = () =>
                element.Should().NotBe(otherElement);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_a_deep_xml_element_is_not_equal_to_a_different_xml_element_it_should_succeed()
        {
            // Arrange
            var differentElement =
                new XElement("parent",
                    new XElement("child",
                        new XElement("grandChild")));
            var element =
                new XElement("parent",
                    new XElement("child",
                        new XElement("grandChild2")));

            // Act
            Action act = () => element.Should().NotBe(differentElement);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_an_xml_element_is_not_equal_to_the_same_xml_element_it_should_fail()
        {
            // Arrange
            var theElement = new XElement("element");
            var sameElement = theElement;

            // Act
            Action act = () =>
                theElement.Should().NotBe(sameElement, "because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>()
                .WithMessage("Did not expect theElement to be <element /> because we want to test the failure message.");
        }

        [Fact]
        public void When_an_element_is_not_supposed_to_be_null_it_succeeds()
        {
            // Arrange
            XElement theElement = new XElement("element");

            // Act
            Action act = () => theElement.Should().NotBe(null);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_a_null_element_is_not_supposed_to_be_an_element_it_succeeds()
        {
            // Arrange
            XElement theElement = null;

            // Act
            Action act = () => theElement.Should().NotBe(new XElement("other"));

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_a_null_element_is_not_supposed_to_be_null_it_fails()
        {
            // Arrange
            XElement theElement = null;

            // Act
            Action act = () => theElement.Should().NotBe(null, "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>()
                .WithMessage("Did not expect theElement to be <null> *failure message*.");
        }

        #endregion

        #region BeNull / NotBeNull

        [Fact]
        public void When_asserting_an_xml_element_is_null_and_it_is_it_should_succeed()
        {
            // Arrange
            XElement element = null;

            // Act
            Action act = () =>
                element.Should().BeNull();

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_an_xml_element_is_null_but_it_is_not_it_should_fail()
        {
            // Arrange
            var theElement = new XElement("element");

            // Act
            Action act = () =>
                theElement.Should().BeNull();

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement to be <null>, but found <element />.");
        }

        [Fact]
        public void When_asserting_an_xml_element_is_null_but_it_is_not_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = new XElement("element");

            // Act
            Action act = () =>
                theElement.Should().BeNull("because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement to be <null> because we want to test the failure message, but found <element />.");
        }

        [Fact]
        public void When_asserting_a_non_null_xml_element_is_not_null_it_should_succeed()
        {
            // Arrange
            var element = new XElement("element");

            // Act
            Action act = () =>
                element.Should().NotBeNull();

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_a_null_xml_element_is_not_null_it_should_fail()
        {
            // Arrange
            XElement theElement = null;

            // Act
            Action act = () =>
                theElement.Should().NotBeNull();

            // Assert
            act.Should().Throw<XunitException>().WithMessage("Expected theElement not to be <null>.");
        }

        [Fact]
        public void When_asserting_a_null_xml_element_is_not_null_it_should_fail_with_descriptive_message()
        {
            // Arrange
            XElement theElement = null;

            // Act
            Action act = () =>
                theElement.Should().NotBeNull("because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement not to be <null> because we want to test the failure message.");
        }

        #endregion

        #region BeEquivalentTo / NotBeEquivalentTo

        [Fact]
        public void When_asserting_a_xml_element_is_equivalent_to_the_same_xml_element_it_should_succeed()
        {
            // Arrange
            var element = new XElement("element");
            var sameXElement = element;

            // Act
            Action act = () =>
                element.Should().BeEquivalentTo(sameXElement);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_a_xml_element_is_equivalent_to_a_different_xml_element_with_same_structure_it_should_succeed()
        {
            // Arrange
            var element = XElement.Parse("<parent><child /></parent>");
            var otherXElement = XElement.Parse("<parent><child /></parent>");

            // Act
            Action act = () =>
                element.Should().BeEquivalentTo(otherXElement);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_an_empty_xml_element_is_equivalent_to_a_different_selfclosing_xml_element_it_should_succeed()
        {
            // Arrange
            var element = XElement.Parse("<parent><child></child></parent>");
            var otherElement = XElement.Parse("<parent><child /></parent>");

            // Act
            Action act = () =>
                element.Should().BeEquivalentTo(otherElement);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_a_selfclosing_xml_element_is_equivalent_to_a_different_empty_xml_element_it_should_succeed()
        {
            // Arrange
            var element = XElement.Parse("<parent><child /></parent>");
            var otherElement = XElement.Parse("<parent><child></child></parent>");

            // Act
            Action act = () =>
                element.Should().BeEquivalentTo(otherElement);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_a_xml_element_is_equivalent_to_a_xml_element_with_elements_missing_it_should_fail()
        {
            // Arrange
            var theElement = XElement.Parse("<parent><child /><child2 /></parent>");
            var otherXElement = XElement.Parse("<parent><child /></parent>");

            // Act
            Action act = () =>
                theElement.Should().BeEquivalentTo(otherXElement);

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected EndElement \"parent\" in theElement at \"/parent\", but found Element \"child2\".");
        }

        [Fact]
        public void When_asserting_a_xml_element_is_equivalent_to_a_different_xml_element_with_extra_elements_it_should_fail()
        {
            // Arrange
            var theElement = XElement.Parse("<parent><child /></parent>");
            var otherXElement = XElement.Parse("<parent><child /><child2 /></parent>");

            // Act
            Action act = () =>
                theElement.Should().BeEquivalentTo(otherXElement);

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected Element \"child2\" in theElement at \"/parent\", but found EndElement \"parent\".");
        }

        [Fact]
        public void When_asserting_a_xml_element_is_equivalent_to_a_different_xml_element_elements_missing_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse("<parent><child /><child2 /></parent>");
            var otherXElement = XElement.Parse("<parent><child /></parent>");

            // Act
            Action act = () =>
                theElement.Should().BeEquivalentTo(otherXElement, "because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected EndElement \"parent\" in theElement at \"/parent\" because we want to test the failure message, but found Element \"child2\".");
        }

        [Fact]
        public void When_asserting_a_xml_element_is_equivalent_to_a_different_xml_element_with_extra_elements_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse("<parent><child /></parent>");
            var otherXElement = XElement.Parse("<parent><child /><child2 /></parent>");

            // Act
            Action act = () =>
                theElement.Should().BeEquivalentTo(otherXElement, "because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected Element \"child2\" in theElement at \"/parent\" because we want to test the failure message, but found EndElement \"parent\".");
        }

        [Fact]
        public void When_asserting_an_empty_xml_element_is_equivalent_to_a_different_xml_element_with_text_content_it_should_fail()
        {
            // Arrange
            var theElement = XElement.Parse("<parent><child /></parent>");
            var otherXElement = XElement.Parse("<parent><child>text</child></parent>");

            // Act
            Action act = () =>
                theElement.Should().BeEquivalentTo(otherXElement, "because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected content \"text\" in theElement at \"/parent/child\" because we want to test the failure message, but found EndElement \"parent\".");
        }

        [Fact]
        public void When_an_element_is_null_then_be_equivalent_to_null_succeeds()
        {
            XElement theElement = null;

            // Act
            Action act = () => theElement.Should().BeEquivalentTo(null);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_an_element_is_null_then_be_equivalent_to_an_element_fails()
        {
            XElement theElement = null;

            // Act
            Action act = () =>
                theElement.Should().BeEquivalentTo(new XElement("element"), "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>()
                .WithMessage("Expected theElement to be equivalent to <null> *failure message*, but found \"<element />\".");
        }

        [Fact]
        public void When_an_element_is_equivalent_to_null_it_fails()
        {
            XElement theElement = new XElement("element");

            // Act
            Action act = () =>
                theElement.Should().BeEquivalentTo(null, "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>()
                .WithMessage("Expected theElement to be equivalent to \"<element />\" *failure message*, but found <null>.");
        }

        [Fact]
        public void When_asserting_a_xml_element_is_not_equivalent_to_a_different_xml_element_with_elements_missing_it_should_succeed()
        {
            // Arrange
            var element = XElement.Parse("<parent><child /><child2 /></parent>");
            var otherXElement = XElement.Parse("<parent><child /></parent>");

            // Act
            Action act = () =>
                element.Should().NotBeEquivalentTo(otherXElement);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_a_xml_element_is_not_equivalent_to_a_different_xml_element_with_extra_elements_it_should_succeed()
        {
            // Arrange
            var element = XElement.Parse("<parent><child /></parent>");
            var otherXElement = XElement.Parse("<parent><child /><child2 /></parent>");

            // Act
            Action act = () =>
                element.Should().NotBeEquivalentTo(otherXElement);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_a_xml_element_is_not_equivalent_to_a_different_xml_element_with_same_structure_it_should_fail()
        {
            // Arrange
            var theElement = XElement.Parse("<parent><child /></parent>");
            var otherXElement = XElement.Parse("<parent><child /></parent>");

            // Act
            Action act = () =>
                theElement.Should().NotBeEquivalentTo(otherXElement);

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Did not expect theElement to be equivalent, but it is.");
        }

        [Fact]
        public void When_asserting_a_xml_element_is_not_equivalent_to_a_different_xml_element_with_same_contents_but_different_ns_prefixes_it_should_fail()
        {
            // Arrange
            var theElement = XElement.Parse(@"<parent xmlns:ns1=""a""><ns1:child /></parent>");
            var otherXElement = XElement.Parse(@"<parent xmlns:ns2=""a""><ns2:child /></parent>");

            // Act
            Action act = () =>
                theElement.Should().NotBeEquivalentTo(otherXElement);

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Did not expect theElement to be equivalent, but it is.");
        }

        [Fact]
        public void When_asserting_a_xml_element_is_not_equivalent_to_a_different_xml_element_with_same_contents_but_extra_unused_xmlns_declaration_it_should_fail()
        {
            // Arrange
            var theElement = XElement.Parse(@"<xml xmlns:ns1=""a"" />");
            var otherXElement = XElement.Parse("<xml />");

            // Act
            Action act = () =>
                theElement.Should().NotBeEquivalentTo(otherXElement);

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Did not expect theElement to be equivalent, but it is.");
        }

        [Fact]
        public void When_asserting_a_xml_element_is_not_equivalent_to_the_same_xml_element_it_should_fail()
        {
            // Arrange
            var theElement = new XElement("element");
            var sameXElement = theElement;

            // Act
            Action act = () =>
                theElement.Should().NotBeEquivalentTo(sameXElement);

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Did not expect theElement to be equivalent, but it is.");
        }

        [Fact]
        public void When_asserting_a_xml_element_is_not_equivalent_to_a_different_xml_element_with_same_structure_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse("<parent><child /></parent>");
            var otherXElement = XElement.Parse("<parent><child /></parent>");

            // Act
            Action act = () =>
                theElement.Should().NotBeEquivalentTo(otherXElement, "because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Did not expect theElement to be equivalent because we want to test the failure message, but it is.");
        }

        [Fact]
        public void When_asserting_a_xml_element_is_not_equivalent_to_the_same_xml_element_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse("<parent><child /></parent>");
            var sameXElement = theElement;

            // Act
            Action act = () =>
                theElement.Should().NotBeEquivalentTo(sameXElement, "because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Did not expect theElement to be equivalent because we want to test the failure message, but it is.");
        }

        [Fact]
        public void
            When_asserting_an_xml_element_is_equivalent_to_a_different_xml_element_with_different_namespace_prefix_it_should_succeed()
        {
            // Arrange
            var subject = XElement.Parse("<xml xmlns=\"urn:a\"/>");
            var expected = XElement.Parse("<a:xml xmlns:a=\"urn:a\"/>");

            // Act
            Action act = () =>
                subject.Should().BeEquivalentTo(expected);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_an_xml_element_is_equivalent_to_a_different_xml_element_which_differs_only_on_unused_namespace_declaration_it_should_succeed()
        {
            // Arrange
            var subject = XElement.Parse("<xml xmlns:a=\"urn:a\"/>");
            var expected = XElement.Parse("<xml/>");

            // Act
            Action act = () =>
                subject.Should().BeEquivalentTo(expected);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_an_xml_element_is_equivalent_to_different_xml_element_which_lacks_attributes_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse("<xml><element b=\"1\"/></xml>");
            var expected = XElement.Parse("<xml><element a=\"b\" b=\"1\"/></xml>");

            // Act
            Action act = () =>
                theElement.Should().BeEquivalentTo(expected, "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected attribute \"a\" in theElement at \"/xml/element\" because we want to test the failure message, but found none.");
        }

        [Fact]
        public void When_asserting_an_xml_element_is_equivalent_to_different_xml_element_which_has_extra_attributes_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse("<xml><element a=\"b\"/></xml>");
            var expected = XElement.Parse("<xml><element/></xml>");

            // Act
            Action act = () =>
                theElement.Should().BeEquivalentTo(expected, "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Did not expect to find attribute \"a\" in theElement at \"/xml/element\" because we want to test the failure message.");
        }

        [Fact]
        public void
            When_asserting_an_xml_element_is_equivalent_to_different_xml_element_which_has_different_attribute_values_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse("<xml><element a=\"b\"/></xml>");
            var expected = XElement.Parse("<xml><element a=\"c\"/></xml>");

            // Act
            Action act = () =>
                theElement.Should().BeEquivalentTo(expected, "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected attribute \"a\" in theElement at \"/xml/element\" to have value \"c\" because we want to test the failure message, but found \"b\".");
        }

        [Fact]
        public void When_asserting_an_xml_element_is_equivalent_to_different_xml_element_which_has_attribute_with_different_namespace_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse("<xml><element xmlns:ns=\"urn:a\" ns:a=\"b\"/></xml>");
            var expected = XElement.Parse("<xml><element a=\"b\"/></xml>");

            // Act
            Action act = () =>
                theElement.Should().BeEquivalentTo(expected, "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Did not expect to find attribute \"ns:a\" in theElement at \"/xml/element\" because we want to test the failure message.");
        }

        [Fact]
        public void When_asserting_an_xml_element_is_equivalent_to_different_xml_element_which_has_different_text_contents_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse("<xml>a</xml>");
            var expected = XElement.Parse("<xml>b</xml>");

            // Act
            Action act = () =>
                theElement.Should().BeEquivalentTo(expected, "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected content to be \"b\" in theElement at \"/xml\" because we want to test the failure message, but found \"a\".");
        }

        [Fact]
        public void When_asserting_an_xml_element_is_equivalent_to_different_xml_element_with_different_comments_it_should_succeed()
        {
            // Arrange
            var subject = XElement.Parse("<xml><!--Comment--><a/></xml>");
            var expected = XElement.Parse("<xml><a/><!--Comment--></xml>");

            // Act
            Action act = () => subject.Should().BeEquivalentTo(expected);

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_a_null_element_is_unexpected_equivalent_to_null_it_fails()
        {
            XElement theElement = null;

            // Act
            Action act = () => theElement.Should().NotBeEquivalentTo(null, "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>()
                .WithMessage("Did not expect theElement to be equivalent *failure message*, but it is.");
        }

        [Fact]
        public void When_a_null_element_is_not_equivalent_to_an_element_it_succeeds()
        {
            XElement theElement = null;

            // Act
            Action act = () => theElement.Should().NotBeEquivalentTo(new XElement("element"));

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_an_element_is_not_equivalent_to_null_it_succeeds()
        {
            XElement theElement = new XElement("element");

            // Act
            Action act = () => theElement.Should().NotBeEquivalentTo(null);

            // Assert
            act.Should().NotThrow();
        }

        #endregion

        #region HaveValue

        [Fact]
        public void When_asserting_element_has_a_specific_value_and_it_does_it_should_succeed()
        {
            // Arrange
            var element = XElement.Parse("<user>grega</user>");

            // Act
            Action act = () =>
                element.Should().HaveValue("grega");

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_element_has_a_specific_value_but_it_has_a_different_value_it_should_throw()
        {
            // Arrange
            var theElement = XElement.Parse("<user>grega</user>");

            // Act
            Action act = () =>
                theElement.Should().HaveValue("stamac");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement 'user' to have value \"stamac\", but found \"grega\".");
        }

        [Fact]
        public void When_asserting_element_has_a_specific_value_but_it_has_a_different_value_it_should_throw_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse("<user>grega</user>");

            // Act
            Action act = () =>
                theElement.Should().HaveValue("stamac", "because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement 'user' to have value \"stamac\" because we want to test the failure message, but found \"grega\".");
        }

        [Fact]
        public void When_xml_element_is_null_then_have_value_should_fail()
        {
            XElement theElement = null;

            // Act
            Action act = () =>
                theElement.Should().HaveValue("value", "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>()
                .WithMessage("Expected the element to have value \"value\" *failure message*, but theElement is <null>.");
        }

        #endregion

        #region HaveAttribute

        [Fact]
        public void When_asserting_element_has_attribute_with_specific_value_and_it_does_it_should_succeed()
        {
            // Arrange
            var element = XElement.Parse(@"<user name=""martin"" />");

            // Act
            Action act = () =>
                element.Should().HaveAttribute("name", "martin");

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_element_has_attribute_with_ns_and_specific_value_and_it_does_it_should_succeed()
        {
            // Arrange
            var element = XElement.Parse(@"<user xmlns:a=""http://www.example.com/2012/test"" a:name=""martin"" />");

            // Act
            Action act = () =>
                element.Should().HaveAttribute(XName.Get("name", "http://www.example.com/2012/test"), "martin");

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_element_has_attribute_with_specific_value_but_attribute_does_not_exist_it_should_fail()
        {
            // Arrange
            var theElement = XElement.Parse(@"<user name=""martin"" />");

            // Act
            Action act = () =>
                theElement.Should().HaveAttribute("age", "36");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement to have attribute \"age\" with value \"36\", but found no such attribute in <user name=\"martin\" />");
        }

        [Fact]
        public void When_asserting_element_has_attribute_with_ns_and_specific_value_but_attribute_does_not_exist_it_should_fail()
        {
            // Arrange
            var theElement = XElement.Parse(@"<user xmlns:a=""http://www.example.com/2012/test"" a:name=""martin"" />");

            // Act
            Action act = () =>
                theElement.Should().HaveAttribute(XName.Get("age", "http://www.example.com/2012/test"), "36");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement to have attribute \"{http://www.example.com/2012/test}age\" with value \"36\","
                + " but found no such attribute in <user xmlns:a=\"http://www.example.com/2012/test\" a:name=\"martin\" />");
        }

        [Fact]
        public void When_asserting_element_has_attribute_with_specific_value_but_attribute_does_not_exist_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse(@"<user name=""martin"" />");

            // Act
            Action act = () =>
                theElement.Should().HaveAttribute("age", "36", "because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement to have attribute \"age\" with value \"36\" because we want to test the failure message,"
                + " but found no such attribute in <user name=\"martin\" />");
        }

        [Fact]
        public void When_asserting_element_has_attribute_with_ns_and_specific_value_but_attribute_does_not_exist_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse(@"<user xmlns:a=""http://www.example.com/2012/test"" a:name=""martin"" />");

            // Act
            Action act = () =>
                theElement.Should().HaveAttribute(XName.Get("age", "http://www.example.com/2012/test"), "36",
                    "because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement to have attribute \"{http://www.example.com/2012/test}age\" with value \"36\""
                + " because we want to test the failure message,"
                + " but found no such attribute in <user xmlns:a=\"http://www.example.com/2012/test\" a:name=\"martin\" />");
        }

        [Fact]
        public void When_asserting_element_has_attribute_with_specific_value_but_attribute_has_different_value_it_should_fail()
        {
            // Arrange
            var theElement = XElement.Parse(@"<user name=""martin"" />");

            // Act
            Action act = () =>
                theElement.Should().HaveAttribute("name", "dennis");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected attribute \"name\" in theElement to have value \"dennis\", but found \"martin\".");
        }

        [Fact]
        public void When_asserting_element_has_attribute_with_ns_and_specific_value_but_attribute_has_different_value_it_should_fail()
        {
            // Arrange
            var theElement = XElement.Parse(@"<user xmlns:a=""http://www.example.com/2012/test"" a:name=""martin"" />");

            // Act
            Action act = () =>
                theElement.Should().HaveAttribute(XName.Get("name", "http://www.example.com/2012/test"), "dennis");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected attribute \"{http://www.example.com/2012/test}name\" in theElement to have value \"dennis\", but found \"martin\".");
        }

        [Fact]
        public void When_asserting_element_has_attribute_with_specific_value_but_attribute_has_different_value_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse(@"<user name=""martin"" />");

            // Act
            Action act = () =>
                theElement.Should().HaveAttribute("name", "dennis", "because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected attribute \"name\" in theElement to have value \"dennis\""
                + " because we want to test the failure message, but found \"martin\".");
        }

        [Fact]
        public void When_asserting_element_has_attribute_with_ns_and_specific_value_but_attribute_has_different_value_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse(@"<user xmlns:a=""http://www.example.com/2012/test"" a:name=""martin"" />");

            // Act
            Action act = () =>
                 theElement.Should().HaveAttribute(XName.Get("name", "http://www.example.com/2012/test"), "dennis",
                    "because we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected attribute \"{http://www.example.com/2012/test}name\" in theElement to have value \"dennis\""
                + " because we want to test the failure message, but found \"martin\".");
        }

        [Fact]
        public void When_xml_element_is_null_then_have_attribute_should_fail()
        {
            XElement theElement = null;

            // Act
            Action act = () =>
                theElement.Should().HaveAttribute("name", "value", "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>()
                .WithMessage(
                    "Expected attribute \"name\" in element to have value \"value\" *failure message*" +
                    ", but theElement is <null>.");
        }

        [Fact]
        public void When_xml_element_is_null_then_have_attribute_with_XName_should_fail()
        {
            XElement theElement = null;

            // Act
            Action act = () =>
                theElement.Should().HaveAttribute((XName)"name", "value", "we want to test the failure {0}", "message");

            // Assert
            act.Should().Throw<XunitException>()
                .WithMessage(
                    "Expected attribute \"name\" in element to have value \"value\" *failure message*" +
                    ", but theElement is <null>.");
        }

        [Fact]
        public void When_asserting_element_has_an_attribute_with_a_null_name_it_should_throw()
        {
            XElement theElement = new XElement("element");

            // Act
            Action act = () =>
                theElement.Should().HaveAttribute(null, "value");

            // Assert
            act.Should().ThrowExactly<ArgumentNullException>()
                .WithParameterName("expectedName");
        }

        [Fact]
        public void When_asserting_element_has_an_attribute_with_a_null_XName_it_should_throw()
        {
            XElement theElement = new XElement("element");

            // Act
            Action act = () =>
                theElement.Should().HaveAttribute((XName)null, "value");

            // Assert
            act.Should().ThrowExactly<ArgumentNullException>()
                .WithParameterName("expectedName");
        }

        [Fact]
        public void When_asserting_element_has_an_attribute_with_an_empty_name_it_should_throw()
        {
            XElement theElement = new XElement("element");

            // Act
            Action act = () =>
                theElement.Should().HaveAttribute(string.Empty, "value");

            // Assert
            act.Should().ThrowExactly<ArgumentNullException>()
                .WithParameterName("expectedName");
        }

        #endregion

        #region HaveElement

        [Fact]
        public void When_asserting_element_has_child_element_and_it_does_it_should_succeed()
        {
            // Arrange
            var element = XElement.Parse(
                @"<parent>
                    <child />
                  </parent>");

            // Act
            Action act = () =>
                element.Should().HaveElement("child");

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_element_has_child_element_with_ns_and_it_does_it_should_succeed()
        {
            // Arrange
            var element = XElement.Parse(
                @"<parent xmlns:c='http://www.example.com/2012/test'>
                    <c:child />
                  </parent>");

            // Act
            Action act = () =>
                element.Should().HaveElement(XName.Get("child", "http://www.example.com/2012/test"));

            // Assert
            act.Should().NotThrow();
        }

        [Fact]
        public void When_asserting_element_has_child_element_but_it_does_not_it_should_fail()
        {
            // Arrange
            var theElement = XElement.Parse(
                @"<parent>
                    <child />
                  </parent>");

            // Act
            Action act = () =>
                theElement.Should().HaveElement("unknown");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement to have child element \"unknown\", but no such child element was found.");
        }

        [Fact]
        public void When_asserting_element_has_child_element_with_ns_but_it_does_not_it_should_fail()
        {
            // Arrange
            var theElement = XElement.Parse(
                @"<parent>
                    <child />
                  </parent>");

            // Act
            Action act = () =>
                theElement.Should().HaveElement(XName.Get("unknown", "http://www.example.com/2012/test"));

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement to have child element \"{{http://www.example.com/2012/test}}unknown\", but no such child element was found.");
        }

        [Fact]
        public void When_asserting_element_has_child_element_but_it_does_not_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse(
                @"<parent>
                    <child />
                  </parent>");

            // Act
            Action act = () =>
                theElement.Should().HaveElement("unknown", "because we want to test the failure message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement to have child element \"unknown\" because we want to test the failure message,"
                + " but no such child element was found.");
        }

        [Fact]
        public void When_asserting_element_has_child_element_with_ns_but_it_does_not_it_should_fail_with_descriptive_message()
        {
            // Arrange
            var theElement = XElement.Parse(
                @"<parent>
                    <child />
                  </parent>");

            // Act
            Action act = () =>
                theElement.Should().HaveElement(XName.Get("unknown", "http://www.example.com/2012/test"),
                    "because we want to test the failure message");

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected theElement to have child element \"{{http://www.example.com/2012/test}}unknown\""
                + " because we want to test the failure message, but no such child element was found.");
        }

        [Fact]
        public void When_asserting_element_has_child_element_it_should_return_the_matched_element_in_the_which_property()
        {
            // Arrange
            var element = XElement.Parse(
                @"<parent>
                    <child attr='1' />
                  </parent>");

            // Act
            var matchedElement = element.Should().HaveElement("child").Subject;

            // Assert
            matchedElement.Should().BeOfType<XElement>()
                .And.HaveAttribute("attr", "1");
            matchedElement.Name.Should().Be(XName.Get("child"));
        }

        [Fact]
        public void When_asserting_element_has_a_child_element_with_a_null_name_it_should_throw()
        {
            XElement theElement = new XElement("element");

            // Act
            Action act = () =>
                theElement.Should().HaveElement(null);

            // Assert
            act.Should().ThrowExactly<ArgumentNullException>()
                .WithParameterName("expected");
        }

        [Fact]
        public void When_asserting_element_has_a_child_element_with_a_null_XName_it_should_throw()
        {
            XElement theElement = new XElement("element");

            // Act
            Action act = () =>
                theElement.Should().HaveElement((XName)null);

            // Assert
            act.Should().ThrowExactly<ArgumentNullException>()
                .WithParameterName("expected");
        }

        [Fact]
        public void When_asserting_element_has_a_child_element_with_an_empty_name_it_should_throw()
        {
            XElement theElement = new XElement("element");

            // Act
            Action act = () =>
                theElement.Should().HaveElement(string.Empty);

            // Assert
            act.Should().ThrowExactly<ArgumentNullException>()
                .WithParameterName("expected");
        }

        #endregion

        #region HaveElement (with occurrence)

        [Fact]
        public void Element_has_two_child_elements_and_it_expected_does_it_succeeds()
        {
            // Arrange
            var element = XElement.Parse(
                @"<parent>
                    <child />
                    <child />
                  </parent>");

            // Act / Assert
            element.Should().HaveElement("child", Exactly.Twice());
        }

        [Fact]
        public void Asserting_element_inside_an_assertion_scope_it_checks_the_whole_assertion_scope_before_failing()
        {
            // Arrange
            XElement element = null;

            // Act
            Action act = () =>
            {
                using (new AssertionScope())
                {
                    element.Should().HaveElement("child", Exactly.Twice());
                    element.Should().HaveElement("child", Exactly.Twice());
                }
            };

            // Assert
            act.Should().NotThrow<NullReferenceException>();
        }

        [Fact]
        public void Element_has_two_child_elements_and_three_expected_it_fails()
        {
            // Arrange
            var element = XElement.Parse(
                @"<parent>
                    <child />
                    <child />
                    <child />
                  </parent>");

            // Act
            Action act = () => element.Should().HaveElement("child", Exactly.Twice());

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected element to have *exactly*2 child element(s) \"child\", but found 3.");
        }

        [Fact]
        public void Element_is_valid_and_expected_null_with_string_overload_it_fails()
        {
            // Arrange
            var element = XElement.Parse(
                @"<parent>
                    <child />
                    <child />
                    <child />
                  </parent>");

            // Act
            Action act = () => element.Should().HaveElement((string)null, Exactly.Twice());

            // Assert
            act.Should().Throw<ArgumentNullException>().WithMessage(
                "Cannot assert the element has an element if the expected name is <null>.*");
        }

        [Fact]
        public void Element_is_valid_and_expected_null_with_x_name_overload_it_fails()
        {
            // Arrange
            var element = XElement.Parse(
                @"<parent>
                    <child />
                    <child />
                    <child />
                  </parent>");

            // Act
            Action act = () => element.Should().HaveElement((XName)null, Exactly.Twice());

            // Assert
            act.Should().Throw<ArgumentNullException>().WithMessage(
                "Cannot assert the element has an element count if the element name is <null>.*");
        }

        [Fact]
        public void Chaining_which_after_asserting_and_the_element_has_more_than_two_child_elements_it_passes()
        {
            // Arrange
            var element = XElement.Parse(
                @"<parent>
                    <child />
                    <child />
                    <child />
                  </parent>");

            // Act / Assert
            element.Should().HaveElement("child", AtLeast.Twice())
                .Which.Should().NotBeNull();
        }

        [Fact]
        public void Null_element_is_expected_to_have_an_element_count_it_should_fail()
        {
            // Arrange
            XElement xElement = null;

            // Act
            Action act = () => xElement.Should().HaveElement("child", AtLeast.Once());

            // Assert
            act.Should().Throw<XunitException>().WithMessage(
                "Expected* to have an element with count of *, but the element itself is <null>.");
        }

        #endregion
    }
}