Added a unit test for cleaning empty targets.

Added a clean empty targets method to CleanOutputProjectRule that removes any targets without content inside of them from the csproj.

test/Microsoft.DotNet.ProjectJsonMigration.Tests/Rules/GivenThatIWantToCleanTheOutputProject.cs

@@ -0,0 +1,38 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.Linq;
+using FluentAssertions;
+using Microsoft.DotNet.Tools.Test.Utilities;
+using Xunit;
+using Microsoft.DotNet.ProjectJsonMigration;
+using System;
+using System.IO;
+using Microsoft.Build.Construction;
+using Microsoft.DotNet.ProjectJsonMigration.Rules;
+using Microsoft.DotNet.Internal.ProjectModel;
+
+namespace Microsoft.DotNet.ProjectJsonMigration.Tests
+{
+    public class GivenThatIWantToCleanTheOutputProject : TestBase
+    {
+        [Fact]
+        public void ItRemovesEmptyTargetsFromTheProject()
+        {
+            var mockProj = ProjectRootElement.Create();
+            var target = mockProj.CreateTargetElement("Test");
+            mockProj.AppendChild(target);
+            target.AddTask("Exec");
+
+            var targetToRemove = mockProj.CreateTargetElement("ToRemove");
+            mockProj.AppendChild(targetToRemove);
+
+            var migrationRuleInputs = new MigrationRuleInputs(Enumerable.Empty<ProjectContext>(), mockProj, null, null);
+            var cleanOutputProjectRule = new CleanOutputProjectRule();
+
+            cleanOutputProjectRule.Apply(null, migrationRuleInputs);
+
+            mockProj.Targets.Should().HaveCount(c => c == 1);
+        }
+    }
+}