ShouldBeAdditionAssertExtensions.cs

using System;
using System.Linq;
using AngleSharp.Diffing.Core;
using AngleSharp.Dom;
using Bunit.Diffing;
using Bunit.Rendering;

namespace Bunit
{
	/// <summary>
	/// A set of addition diff assert extensions 
	/// </summary>
	public static class ShouldBeAdditionAssertExtensions
	{
		/// <summary>
		/// Verifies that the <paramref name="actualChange"/> <see cref="IDiff"/> is an addition,
		/// i.e. that one or more nodes have been added, and verifies that the additions are equal
		/// to the markup specified in the <paramref name="expectedChange"/> input.
		/// </summary>
		/// <param name="actualChange">The change to verify</param>
		/// <param name="expectedChange">The expected additions to verify against</param>
		/// <param name="userMessage">A custom user message to display in case the verification fails.</param>
		public static void ShouldBeAddition(this IDiff actualChange, string expectedChange, string? userMessage = null)
		{
			if (actualChange is null)
				throw new ArgumentNullException(nameof(actualChange));
			if (expectedChange is null)
				throw new ArgumentNullException(nameof(expectedChange));

			var actual = actualChange as UnexpectedNodeDiff ?? throw new DiffChangeAssertException(actualChange.Result, DiffResult.Unexpected, "The change was not an addition.");

			INodeList expected;
			if (actual.Test.Node.GetHtmlParser() is BunitHtmlParser parser)
			{
				expected = parser.Parse(expectedChange);
			}
			else
			{
				using var newParser = new BunitHtmlParser();
				expected = newParser.Parse(expectedChange);
			}

			ShouldBeAddition(actualChange, expected, userMessage);
		}

		/// <summary>
		/// Verifies that the <paramref name="actualChange"/> <see cref="IDiff"/> is an addition,
		/// i.e. that one or more nodes have been added, and verifies that the additions are equal
		/// to the rendered markup from the <paramref name="expectedChange"/> <see cref="IRenderedFragmentBase"/>.
		/// </summary>
		/// <param name="actualChange">The change to verify</param>
		/// <param name="expectedChange">The expected additions to verify against</param>
		/// <param name="userMessage">A custom user message to display in case the verification fails.</param>
		public static void ShouldBeAddition(this IDiff actualChange, IRenderedFragment expectedChange, string? userMessage = null)
		{
			if (expectedChange is null)
				throw new ArgumentNullException(nameof(expectedChange));
			ShouldBeAddition(actualChange, expectedChange.Nodes, userMessage);
		}

		/// <summary>
		/// Verifies that the <paramref name="actualChange"/> <see cref="IDiff"/> is an addition,
		/// i.e. that one or more nodes have been added, and verifies that the additions are equal
		/// to the <paramref name="expectedChange"/> nodes.
		/// </summary>
		/// <param name="actualChange">The change to verify</param>
		/// <param name="expectedChange">The expected additions to verify against</param>
		/// <param name="userMessage">A custom user message to display in case the verification fails.</param>
		public static void ShouldBeAddition(this IDiff actualChange, INodeList expectedChange, string? userMessage = null)
		{
			if (actualChange is null)
				throw new ArgumentNullException(nameof(actualChange));
			if (expectedChange is null)
				throw new ArgumentNullException(nameof(expectedChange));

			var actual = actualChange as UnexpectedNodeDiff ?? throw new DiffChangeAssertException(actualChange.Result, DiffResult.Unexpected, "The change was not an addition.");
			var comparer = actual.Test.Node.GetHtmlComparer() ?? new HtmlComparer();

			var diffs = comparer.Compare(expectedChange, actual.Test.Node.AsEnumerable()).ToList();

			if (diffs.Count != 0)
			{
				throw new HtmlEqualException(diffs, expectedChange, actual.Test.Node, userMessage);
			}
		}
	}
}