Fix spurious error generated when importing cmdlets from an in-memory assembly (#4117)

src/System.Management.Automation/engine/InitialSessionState.cs

@@ -4494,10 +4494,14 @@ namespace System.Management.Automation.Runspaces
             string throwAwayHelpFile = null;
             PSSnapInHelpers.AnalyzePSSnapInAssembly(assembly, assemblyPath, null, module, true, out cmdlets, out aliases, out providers, out throwAwayHelpFile);
 
-            SessionStateAssemblyEntry assemblyEntry =
-                new SessionStateAssemblyEntry(assembly.FullName, assemblyPath);
-
-            this.Assemblies.Add(assemblyEntry);
+            // If this is an in-memory assembly, don't added it to the list of AssemblyEntries
+            // since it can't be loaded by path or name
+            if (! string.IsNullOrEmpty(assembly.Location))
+            {
+                SessionStateAssemblyEntry assemblyEntry =
+                    new SessionStateAssemblyEntry(assembly.FullName, assemblyPath);
+                this.Assemblies.Add(assemblyEntry);
+            }
 
             if (cmdlets != null)
             {

src/System.Management.Automation/engine/Modules/ModuleCmdletBase.cs

@@ -6843,6 +6843,15 @@ namespace Microsoft.PowerShell.Commands
 
                 assemblyVersion = GetAssemblyVersionNumber(assemblyToLoad);
                 assembly = assemblyToLoad;
+                // If this is an in-memory only assembly, add it directly to the assembly cache if
+                // it isn't already there.
+                if (string.IsNullOrEmpty(assembly.Location))
+                {
+                    if (! Context.AssemblyCache.ContainsKey(assembly.FullName))
+                    {
+                        Context.AssemblyCache.Add(assembly.FullName, assembly);
+                    }
+                }
             }
             else
             {
@@ -7196,7 +7205,6 @@ namespace Microsoft.PowerShell.Commands
             {
                 AddModuleToModuleTables(this.Context, this.TargetSessionState.Internal, module);
             }
-
             return module;
         }
 

test/powershell/Language/Parser/ParameterBinding.Tests.ps1

@@ -47,7 +47,7 @@ Describe 'Argument transformation attribute on optional argument with explicit $
 '@
     $mod = Add-Type -PassThru -TypeDefinition $tdefinition
 
-    Import-Module $mod[0].Assembly
+    Import-Module $mod[0].Assembly -ErrorVariable ErrorImportingModule
 
     function Invoke-ScriptFunctionTakesObject
     {
@@ -68,6 +68,10 @@ Describe 'Argument transformation attribute on optional argument with explicit $
     }
 
 
+    It "There was no error importing the in-memory module" {
+        $ErrorImportingModule | Should Be $null
+    }
+
     It "Script function takes object" {
         Invoke-ScriptFunctionTakesObject | Should Be 42
     }