Fix AssemblyInstaller failing to UnRegister dll if missing from disk.

DNN Platform/Library/Services/Installer/Installers/AssemblyInstaller.cs

@@ -289,7 +289,13 @@ private void RemoveBindingRedirect(InstallFile file)
         /// <returns><c>true</c> if the XML Merge was applied successfully, <c>false</c> if the file was not a strong-named assembly or could not be read.</returns>
         private bool ApplyXmlMerge(InstallFile file, string xmlMergeFile)
         {
-            var assemblyName = ReadAssemblyName(Path.Combine(this.PhysicalBasePath, file.FullName));
+            var assemblyFileFullPath = Path.Combine(this.PhysicalBasePath, file.FullName);
+            if (!File.Exists(assemblyFileFullPath))
+            {
+                return false;
+            }
+
+            var assemblyName = ReadAssemblyName(assemblyFileFullPath);
             var publicKeyToken = ReadPublicKey(assemblyName);
             if (string.IsNullOrEmpty(publicKeyToken))
             {

DNN Platform/Tests/DotNetNuke.Tests.Core/DotNetNuke.Tests.Core.csproj

@@ -198,6 +198,7 @@
     <Compile Include="Services\ClientCapability\TestClientCapability.cs" />
     <Compile Include="Services\CryptographyProviders\FipsCompilanceCryptographyProviderTests.cs" />
     <Compile Include="Services\CryptographyProviders\CoreCryptographyProviderTests.cs" />
+    <Compile Include="Services\Installer\AssemblyInstallerTests.cs" />
     <Compile Include="Services\Localization\LocalizationTests.cs" />
     <Compile Include="Services\Mobile\PreviewProfileControllerTests.cs" />
     <Compile Include="Services\Mobile\RedirectionControllerTests.cs" />

DNN Platform/Tests/DotNetNuke.Tests.Core/Services/Installer/AssemblyInstallerTests.cs

@@ -0,0 +1,73 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information
+namespace DotNetNuke.Tests.Core.Services.Installer
+{
+    using System;
+    using System.IO;
+    using System.Linq;
+    using System.Xml.XPath;
+
+    using DotNetNuke.Abstractions;
+    using DotNetNuke.Abstractions.Application;
+    using DotNetNuke.Common;
+    using DotNetNuke.Services.Installer;
+    using DotNetNuke.Services.Installer.Installers;
+    using DotNetNuke.Services.Installer.Packages;
+    using DotNetNuke.Services.Localization;
+    using DotNetNuke.Tests.Utilities;
+    using DotNetNuke.Tests.Utilities.Mocks;
+    using Microsoft.Extensions.DependencyInjection;
+    using Moq;
+    using NUnit.Framework;
+
+    public class AssemblyInstallerTests : DnnUnitTest
+    {
+        [SetUp]
+        public void SetUp()
+        {
+            var serviceCollection = new ServiceCollection();
+            var appInfo = new Mock<IApplicationStatusInfo>();
+            appInfo.SetupGet(app => app.Status).Returns(UpgradeStatus.None);
+            serviceCollection.AddTransient<IApplicationStatusInfo>(container => appInfo.Object);
+            serviceCollection.AddTransient<INavigationManager>(container => Mock.Of<INavigationManager>());
+            Globals.DependencyProvider = serviceCollection.BuildServiceProvider();
+
+            var dataProvider = MockComponentProvider.CreateDataProvider();
+            dataProvider.Setup(p => p.UnRegisterAssembly(It.IsAny<int>(), It.IsAny<string>())).Returns(true);
+
+            LocalizationProvider.SetTestableInstance(new Mock<ILocalizationProvider>().Object);
+        }
+
+        [Test]
+        public void Install_UnRegisterAssembly_ShouldSucceed_WhenFileIsMissing()
+        {
+            var installer = new AssemblyInstaller
+            {
+                DeleteFiles = true,
+                Package = new PackageInfo(new InstallerInfo(Directory.GetCurrentDirectory(), InstallMode.Install)),
+            };
+            var manifestNav = GetUnRegisterAssemblyManifest();
+            installer.ReadManifest(manifestNav);
+
+            installer.Install();
+
+            Assert.IsTrue(installer.Log.Valid);
+        }
+
+        private static XPathNavigator GetUnRegisterAssemblyManifest()
+        {
+            var doc = new XPathDocument(new StringReader(@"
+<assemblies>
+    <assembly action=""UnRegister"">
+        <path>bin\Providers</path>
+        <name>FakeAssembly.dll</name>
+        <sourceFileName>FakeAssembly.dll</sourceFileName>
+        <version>01.02.03</version>
+    </assembly>
+</assemblies>
+"));
+            return doc.CreateNavigator();
+        }
+    }
+}