common/UnitTests/AspNetCore/Extensions/ModelStateDictionaryExtensionsTests.cs

using System;
using System.Linq;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace UnitTests.AspNetCore.Extensions
{
	[TestClass]
	[System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
	public class ModelStateDictionaryExtensionsTests
	{
		private TestModel testModel;

		[TestInitialize]
		public void InitializeTests()
		{
			testModel = new TestModel
			{
				ValueA = "A",
				ValueB = "B",
				SubModel = new TestSubModel
				{
					SubValueA = "a",
					SubValueB = "b"
				}
			};
		}

		[TestMethod]
		public void ShouldAddNormalModelError()
		{
			// arrange
			var modelState = new ModelStateDictionary();

			// act
			modelState.AddModelError(testModel, m => m.ValueA, "ShitHappens");

			// assert
			Assert.AreEqual(1, modelState.Count);
			Assert.AreEqual("ValueA", modelState.Keys.First());
			Assert.AreEqual("ShitHappens", modelState.Values.First().Errors.First().ErrorMessage);
		}

		[TestMethod]
		public void ShouldAddExtendedModelError()
		{
			// arrange
			var modelState = new ModelStateDictionary();

			// act
			modelState.AddModelError(testModel, m => m.SubModel.SubValueB, "ShitHappens");

			// assert
			Assert.AreEqual(1, modelState.Count);
			Assert.AreEqual("SubModel.SubValueB", modelState.Keys.First());
			Assert.AreEqual("ShitHappens", modelState.Values.First().Errors.First().ErrorMessage);
		}

		[TestMethod]
		[ExpectedException(typeof(ArgumentNullException))]
		public void ShouldThrowArgumentNull()
		{
			// arrange
			ModelStateDictionary modelState = null;

			// act
			modelState.AddModelError(testModel, m => m.SubModel.SubValueB, "ShitHappens");
		}

		[TestMethod]
		[ExpectedException(typeof(InvalidOperationException))]
		public void ShouldThrowInvalidOperation()
		{
			// arrange
			var modelState = new ModelStateDictionary();

			// act
			modelState.AddModelError(testModel, m => m, "ShitHappens");
		}

		internal class TestModel
		{
			public string ValueA { get; set; }

			public string ValueB { get; set; }

			public TestSubModel SubModel { get; set; }
		}

		internal class TestSubModel
		{
			public string SubValueA { get; set; }

			public string SubValueB { get; set; }
		}
	}
}