Throw exception if Import-Module fails

src/AppInstallerSharedLib/Public/AppInstallerErrors.h

@@ -173,6 +173,7 @@
 #define WINGET_CONFIG_ERROR_UNIT_INVOKE_TEST          ((HRESULT)0x8A15C105)
 #define WINGET_CONFIG_ERROR_UNIT_INVOKE_SET           ((HRESULT)0x8A15C106)
 #define WINGET_CONFIG_ERROR_UNIT_MODULE_CONFLICT      ((HRESULT)0x8A15C107)
+#define WINGET_CONFIG_ERROR_UNIT_IMPORT_MODULE        ((HRESULT)0x8A15C108)
 
 namespace AppInstaller
 {

src/Microsoft.Management.Configuration.Processor/Exceptions/ErrorCodes.cs

@@ -45,5 +45,10 @@ internal static class ErrorCodes
         /// Internal error calling Get-DscResource. More than one module found with the same version.
         /// </summary>
         internal const int WinGetConfigUnitModuleConflict = unchecked((int)0x8A15C107);
+
+        /// <summary>
+        /// The module where the DSC resource is implemented cannot be imported.
+        /// </summary>
+        internal const int WinGetConfigUnitImportModule = unchecked((int)0x8A15C108);
     }
 }

src/Microsoft.Management.Configuration.Processor/Exceptions/ImportModuleException.cs

@@ -0,0 +1,33 @@
+// -----------------------------------------------------------------------------
+// <copyright file="BlockedFileException.cs" company="Microsoft Corporation">
+//     Copyright (c) Microsoft Corporation. Licensed under the MIT License.
+// </copyright>
+// -----------------------------------------------------------------------------
+
+namespace Microsoft.Management.Configuration.Processor.Exceptions
+{
+    using System;
+
+    /// <summary>
+    /// Import-Module threw an exception.
+    /// </summary>
+    internal class ImportModuleException : Exception
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ImportModuleException"/> class.
+        /// </summary>
+        /// <param name="moduleName">Module name.</param>
+        /// <param name="inner">Inner exception.</param>
+        public ImportModuleException(string? moduleName, Exception inner)
+            : base($"Could not import module: {moduleName?.ToString() ?? "<no module>"}", inner)
+        {
+            this.HResult = ErrorCodes.WinGetConfigUnitImportModule;
+            this.ModuleName = moduleName;
+        }
+
+        /// <summary>
+        /// Gets the module name.
+        /// </summary>
+        public string? ModuleName { get; }
+    }
+}

src/Microsoft.Management.Configuration.Processor/ProcessorEnvironments/HostedEnvironment.cs

@@ -8,6 +8,7 @@ namespace Microsoft.Management.Configuration.Processor.Runspaces
 {
     using System;
     using System.Collections.Generic;
+    using System.IO;
     using System.Linq;
     using System.Management.Automation;
     using System.Management.Automation.Runspaces;
@@ -196,6 +197,23 @@ public void ImportModule(ModuleSpecification moduleSpecification)
             this.OnDiagnostics(DiagnosticLevel.Verbose, pwsh);
         }
 
+        /// <inheritdoc/>
+        public void ImportModule(string path)
+        {
+            if (!File.Exists(path))
+            {
+                throw new FileNotFoundException(path);
+            }
+
+            using PowerShell pwsh = PowerShell.Create(this.Runspace);
+
+            _ = pwsh.AddCommand(Commands.ImportModule)
+                    .AddParameter(Parameters.Name, path)
+                    .Invoke();
+
+            this.OnDiagnostics(DiagnosticLevel.Verbose, pwsh);
+        }
+
         /// <inheritdoc/>
         public PSObject? GetInstalledModule(ModuleSpecification moduleSpecification)
         {

src/Microsoft.Management.Configuration.Processor/ProcessorEnvironments/IProcessorEnvironment.cs

@@ -98,11 +98,17 @@ internal interface IProcessorEnvironment
         PSModuleInfo? GetAvailableModule(string path);
 
         /// <summary>
-        /// Call Import-Module with the fully qualified name.
+        /// Calls Import-Module with the fully qualified name.
         /// </summary>
         /// <param name="moduleSpecification">Module specification.</param>
         void ImportModule(ModuleSpecification moduleSpecification);
 
+        /// <summary>
+        /// Calls Import-Module with a file path.
+        /// </summary>
+        /// <param name="path">Module file path.</param>
+        void ImportModule(string path);
+
         /// <summary>
         /// Calls Get-InstalledModule.
         /// </summary>

src/Microsoft.Management.Configuration.Processor/Public/ConfigurationSetProcessorFactory.cs

@@ -115,6 +115,7 @@ internal void OnDiagnostics(DiagnosticLevel level, PowerShell pwsh)
                         {
                             builder.Append($"{p.Name} = '{p.Value}' ");
                         }
+
                         builder.Append("]");
                     }
 

src/Microsoft.Management.Configuration.Processor/Set/ConfigurationSetProcessor.cs

@@ -202,6 +202,24 @@ private DscResourceInfoInternal PrepareUnitForProcessing(ConfigurationUnitIntern
                 }
             }
 
+            // PowerShell will prompt the user when a module that is downloaded from the internet is imported.
+            // For a hosted environment, this will throw an exception because it doesn't support user interaction.
+            // In the case we don't import the module here, eventually Invoke-DscResource will fail for class
+            // resources because they will call a method on a null obj. It is easier to just fail here.
+            // The exception being thrown will have the correct details (user needs to call Unblock-File)
+            // instead of the criptic Invoke with 0 arguments.
+            if (dscResourceInfo.Path is not null)
+            {
+                try
+                {
+                    this.ProcessorEnvironment.ImportModule(dscResourceInfo.Path);
+                }
+                catch (Exception e)
+                {
+                    throw new ImportModuleException(dscResourceInfo.ModuleName, e);
+                }
+            }
+
             return dscResourceInfo;
         }