add: Assertion extension to use IEqualityComparer

Author: stefanedwards

Interfaces/Cosmos.DataTransfer.Common.UnitTests/AssertExtension.cs

@@ -0,0 +1,37 @@
+using System.Diagnostics.CodeAnalysis;
+using Moq;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace Cosmos.DataTransfer.Common.UnitTests;
+
+/// <summary>
+/// Method for suppling Assert.AreEqual with a custom equality comparer
+/// (IEqualityComparer).
+/// </summary>
+public static class AssertExtension {
+    public static void AreEqual<T>(this Assert that, T expected, T actual, IEqualityComparer<T> comparer) {
+        if (!comparer.Equals(expected, actual))
+            throw new AssertFailedException(
+                $"Assert.AreEqual failed. Expected:<{expected!}>. Actual:<{actual!}>.");
+    }
+}
+
+[TestClass]
+public class AssertExtensionTests {
+    [TestMethod]
+    public void AreEqual_ThrowsArgumentNullException() {
+        var bad_comparer = new Mock<IEqualityComparer<int>>();
+        bad_comparer.Setup((x) => x.Equals(It.IsAny<int>(), It.IsAny<int>()))
+            .Returns(false);
+        var e = Assert.ThrowsException<AssertFailedException>(
+            () => Assert.That.AreEqual(1, 1, bad_comparer.Object)
+        );
+        Assert.AreEqual("Assert.AreEqual failed. Expected:<1>. Actual:<1>.", e.Message);
+
+        var good_comparer = new Mock<IEqualityComparer<int>>();
+        good_comparer.Setup((x) => x.Equals(It.IsAny<int>(), It.IsAny<int>()))
+            .Returns(true);
+        Assert.That.AreEqual(1, 1, good_comparer.Object); // No Exceptions thrown
+    }
+}
+

Interfaces/Cosmos.DataTransfer.Common.UnitTests/Cosmos.DataTransfer.Common.UnitTests.csproj

@@ -16,6 +16,7 @@
     <PackageReference Include="MSTest.TestAdapter" Version="2.2.10" />
     <PackageReference Include="MSTest.TestFramework" Version="2.2.10" />
     <PackageReference Include="coverlet.collector" Version="3.1.2" />
+    <PackageReference Include="Moq" Version="4.18.4" />
     <PackageReference Include="coverlet.msbuild" Version="2.8.0">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>