XDocumentAssertions.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Xml;
using System.Xml.Linq;

using FluentAssertions.Common;
using FluentAssertions.Execution;
using FluentAssertions.Primitives;
using FluentAssertions.Xml.Equivalency;

namespace FluentAssertions.Xml
{
    /// <summary>
    /// Contains a number of methods to assert that an <see cref="XDocument"/> is in the expected state.
    /// </summary>
    [DebuggerNonUserCode]
    public class XDocumentAssertions : ReferenceTypeAssertions<XDocument, XDocumentAssertions>
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="XDocumentAssertions" /> class.
        /// </summary>
        public XDocumentAssertions(XDocument document)
            : base(document)
        {
        }

        /// <summary>
        /// Asserts that the current <see cref="XDocument"/> equals the <paramref name="expected"/> document,
        /// using its <see cref="object.Equals(object)" /> implementation.
        /// </summary>
        /// <param name="expected">The expected document</param>
        /// <param name="because">
        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
        /// </param>
        /// <param name="becauseArgs">
        /// Zero or more objects to format using the placeholders in <paramref name="because" />.
        /// </param>
        public AndConstraint<XDocumentAssertions> Be(XDocument expected, string because = "", params object[] becauseArgs)
        {
            Execute.Assertion
                .ForCondition(Equals(Subject, expected))
                .BecauseOf(because, becauseArgs)
                .FailWith("Expected {context:subject} to be {0}{reason}, but found {1}.", expected, Subject);

            return new AndConstraint<XDocumentAssertions>(this);
        }

        /// <summary>
        /// Asserts that the current <see cref="XDocument"/> does not equal the <paramref name="unexpected"/> document,
        /// using its <see cref="object.Equals(object)" /> implementation.
        /// </summary>
        /// <param name="unexpected">The unexpected document</param>
        /// <param name="because">
        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
        /// </param>
        /// <param name="becauseArgs">
        /// Zero or more objects to format using the placeholders in <paramref name="because" />.
        /// </param>
        public AndConstraint<XDocumentAssertions> NotBe(XDocument unexpected, string because = "", params object[] becauseArgs)
        {
            Execute.Assertion
                .BecauseOf(because, becauseArgs)
                .ForCondition(!Equals(Subject, unexpected))
                .FailWith("Did not expect {context:subject} to be {0}{reason}.", unexpected);

            return new AndConstraint<XDocumentAssertions>(this);
        }

        /// <summary>
        /// Asserts that the current <see cref="XDocument"/> is equivalent to the <paramref name="expected"/> document,
        /// using its <see cref="XNode.DeepEquals(XNode, XNode)" /> implementation.
        /// </summary>
        /// <param name="expected">The expected document</param>
        /// <param name="because">
        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
        /// </param>
        /// <param name="becauseArgs">
        /// Zero or more objects to format using the placeholders in <paramref name="because" />.
        /// </param>
        public AndConstraint<XDocumentAssertions> BeEquivalentTo(XDocument expected, string because = "", params object[] becauseArgs)
        {
            using (XmlReader subjectReader = Subject?.CreateReader())
            using (XmlReader otherReader = expected?.CreateReader())
            {
                var xmlReaderValidator = new XmlReaderValidator(subjectReader, otherReader, because, becauseArgs);
                xmlReaderValidator.Validate(shouldBeEquivalent: true);
            }

            return new AndConstraint<XDocumentAssertions>(this);
        }

        /// <summary>
        /// Asserts that the current <see cref="XDocument"/> is not equivalent to the <paramref name="unexpected"/> document,
        /// using its <see cref="XNode.DeepEquals(XNode, XNode)" /> implementation.
        /// </summary>
        /// <param name="unexpected">The unexpected document</param>
        /// <param name="because">
        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
        /// </param>
        /// <param name="becauseArgs">
        /// Zero or more objects to format using the placeholders in <paramref name="because" />.
        /// </param>
        public AndConstraint<XDocumentAssertions> NotBeEquivalentTo(XDocument unexpected, string because = "", params object[] becauseArgs)
        {
            using (XmlReader subjectReader = Subject?.CreateReader())
            using (XmlReader otherReader = unexpected?.CreateReader())
            {
                var xmlReaderValidator = new XmlReaderValidator(subjectReader, otherReader, because, becauseArgs);
                xmlReaderValidator.Validate(shouldBeEquivalent: false);
            }

            return new AndConstraint<XDocumentAssertions>(this);
        }

        /// <summary>
        /// Asserts that the current <see cref="XDocument"/> has a root element with the specified
        /// <paramref name="expected"/> name.
        /// </summary>
        /// <param name="expected">The name of the expected root element of the current document.</param>
        /// <param name="because">
        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
        /// </param>
        /// <param name="becauseArgs">
        /// Zero or more objects to format using the placeholders in <paramref name="because" />.
        /// </param>
        public AndWhichConstraint<XDocumentAssertions, XElement> HaveRoot(string expected, string because = "",
            params object[] becauseArgs)
        {
            Guard.ThrowIfArgumentIsNull(expected, nameof(expected),
                "Cannot assert the document has a root element if the expected name is <null>.");

            return HaveRoot(XNamespace.None + expected, because, becauseArgs);
        }

        /// <summary>
        /// Asserts that the current <see cref="XDocument"/> has a root element with the specified
        /// <paramref name="expected"/> name.
        /// </summary>
        /// <param name="expected">The full name <see cref="XName"/> of the expected root element of the current document.</param>
        /// <param name="because">
        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
        /// </param>
        /// <param name="becauseArgs">
        /// Zero or more objects to format using the placeholders in <paramref name="because" />.
        /// </param>
        public AndWhichConstraint<XDocumentAssertions, XElement> HaveRoot(XName expected, string because = "", params object[] becauseArgs)
        {
            if (Subject is null)
            {
                throw new InvalidOperationException("Cannot assert the document has a root element if the document itself is <null>.");
            }

            Guard.ThrowIfArgumentIsNull(expected, nameof(expected),
                "Cannot assert the document has a root element if the expected name is <null>.");

            XElement root = Subject.Root;

            Execute.Assertion
                .ForCondition((root is not null) && (root.Name == expected))
                .BecauseOf(because, becauseArgs)
                .FailWith(
                    "Expected {context:subject} to have root element {0}{reason}, but found {1}.",
                    expected.ToString(), Subject);

            return new AndWhichConstraint<XDocumentAssertions, XElement>(this, root);
        }

        /// <summary>
        /// Asserts that the <see cref="XDocument.Root"/> element of the current <see cref="XDocument"/> has a direct
        /// child element with the specified <paramref name="expected"/> name.
        /// </summary>
        /// <param name="expected">
        /// The name of the expected child element of the current document's <see cref="XDocument.Root"/> element.
        /// </param>
        /// <param name="because">
        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
        /// </param>
        /// <param name="becauseArgs">
        /// Zero or more objects to format using the placeholders in <paramref name="because" />.
        /// </param>
        public AndWhichConstraint<XDocumentAssertions, XElement> HaveElement(string expected, string because = "",
            params object[] becauseArgs)
        {
            Guard.ThrowIfArgumentIsNull(expected, nameof(expected),
                "Cannot assert the document has an element if the expected name is <null>.");

            return HaveElement(XNamespace.None + expected, because, becauseArgs);
        }

        /// <summary>
        /// Asserts that the <see cref="XDocument.Root"/> element of the current <see cref="XDocument"/> has a direct
        /// child element with the specified <paramref name="expected"/> name.
        /// </summary>
        /// <param name="expected">
        /// The name of the expected child element of the current document's <see cref="XDocument.Root"/> element.
        /// </param>
        /// <param name="occurrenceConstraint">
        /// A constraint specifying the number of times the specified elements should appear.
        /// </param>
        /// <param name="because">
        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
        /// </param>
        /// <param name="becauseArgs">
        /// Zero or more objects to format using the placeholders in <paramref name="because" />.
        /// </param>
        public AndWhichConstraint<XDocumentAssertions, XElement> HaveElement(string expected,
            OccurrenceConstraint occurrenceConstraint, string because = "", params object[] becauseArgs)
        {
            Guard.ThrowIfArgumentIsNull(expected, nameof(expected),
                "Cannot assert the document has an element if the expected name is <null>.");

            return HaveElement(XNamespace.None + expected, occurrenceConstraint, because, becauseArgs);
        }

        /// <summary>
        /// Asserts that the <see cref="XDocument.Root"/> element of the current <see cref="XDocument"/> has a direct
        /// child element with the specified <paramref name="expected"/> name.
        /// </summary>
        /// <param name="expected">
        /// The full name <see cref="XName"/> of the expected child element of the current document's <see cref="XDocument.Root"/> element.
        /// </param>
        /// <param name="because">
        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
        /// </param>
        /// <param name="becauseArgs">
        /// Zero or more objects to format using the placeholders in <paramref name="because" />.
        /// </param>
        public AndWhichConstraint<XDocumentAssertions, XElement> HaveElement(XName expected, string because = "",
            params object[] becauseArgs)
        {
            if (Subject is null)
            {
                throw new InvalidOperationException("Cannot assert the document has an element if the document itself is <null>.");
            }

            Guard.ThrowIfArgumentIsNull(expected, nameof(expected),
                    "Cannot assert the document has an element if the expected name is <null>.");

            Execute.Assertion
                .ForCondition(Subject.Root is not null)
                .BecauseOf(because, becauseArgs)
                .FailWith(
                    "Expected {context:subject} to have root element with child {0}{reason}, but it has no root element.",
                    expected.ToString());

            XElement xElement = Subject.Root.Element(expected);
            Execute.Assertion
                .ForCondition(xElement is not null)
                .BecauseOf(because, becauseArgs)
                .FailWith(
                    "Expected {context:subject} to have root element with child {0}{reason}, but no such child element was found.",
                    expected.ToString());

            return new AndWhichConstraint<XDocumentAssertions, XElement>(this, xElement);
        }

        /// <summary>
        /// Asserts that the <see cref="XDocument.Root"/> element of the current <see cref="XDocument"/> has the specified occurrence of
        /// child elements with the specified <paramref name="expected"/> name.
        /// </summary>
        /// <param name="expected">
        /// The full name <see cref="XName"/> of the expected child element of the current document's <see cref="XDocument.Root"/> element.
        /// </param>
        /// <param name="occurrenceConstraint">
        /// A constraint specifying the number of times the specified elements should appear.
        /// </param>
        /// <param name="because">
        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
        /// </param>
        /// <param name="becauseArgs">
        /// Zero or more objects to format using the placeholders in <paramref name="because" />.
        /// </param>
        public AndWhichConstraint<XDocumentAssertions, XElement> HaveElement(XName expected,
            OccurrenceConstraint occurrenceConstraint, string because = "",
            params object[] becauseArgs)
        {
            Execute.Assertion
                .ForCondition(Subject is not null)
                .BecauseOf(because, becauseArgs)
                .FailWith("Cannot assert the count if the document itself is <null>.");

            Guard.ThrowIfArgumentIsNull(expected, nameof(expected),
                "Cannot assert the document has an element count if the element name is <null>.");

            bool success = Execute.Assertion
                .ForCondition(Subject.Root is not null)
                .BecauseOf(because, becauseArgs)
                .FailWith(
                    "Expected {context:subject} to have root element with child {0}{reason}, but it has no root element.",
                    expected.ToString());

            IEnumerable<XElement> xElements = Enumerable.Empty<XElement>();

            if (success)
            {
                xElements = Subject.Root.Elements(expected);
                int actualCount = xElements.Count();

                Execute.Assertion
                    .ForConstraint(occurrenceConstraint, actualCount)
                    .BecauseOf(because, becauseArgs)
                    .FailWith(
                        "Expected {context:subject} to have {0} child element(s) {1}{reason}, but found {2}.",
                        occurrenceConstraint.ExpectedCount, expected.ToString(), actualCount);
            }

            return new AndWhichConstraint<XDocumentAssertions, XElement>(this, xElements);
        }

        /// <summary>
        /// Returns the type of the subject the assertion applies on.
        /// </summary>
        protected override string Identifier => "XML document";
    }
}