use config for shim (#6)

remove some tests that rely on dynamo for test discovery

DSIronPython/DSIronPython.csproj

@@ -19,14 +19,19 @@
 
 		<PackageReference Include="IronPython" Version="2.7.12" />
 		<PackageReference Include="IronPython.StdLib" Version="2.7.12" />
-
+		<PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="8.0.0" />
 
 	</ItemGroup>
 	<ItemGroup>
 		<AssemblyAttribute Include="System.Runtime.CompilerServices.InternalsVisibleToAttribute">
 			<_Parameter1>IronPythonTests</_Parameter1>
 		</AssemblyAttribute>
 	</ItemGroup>
+	<ItemGroup>
+	  <None Update="appsettings.json">
+	    <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+	  </None>
+	</ItemGroup>
 
 	<Target Name="copypkgjson" AfterTargets="Build">
 		<Copy SourceFiles="pkg.json" DestinationFolder="$(OutputPath)..\" />

DSIronPython/IronPythonEvaluator.cs

@@ -12,7 +12,7 @@
 using Dynamo.Session;
 using Dynamo.Utilities;
 using IronPython.Hosting;
-
+using Microsoft.Extensions.Configuration;
 using Microsoft.Scripting.Hosting;
 using Microsoft.Scripting.Utils;
 
@@ -25,6 +25,8 @@ namespace DSIronPython
     [IsVisibleInDynamoLibrary(false)]
     public class IronPythonEvaluator : Dynamo.PythonServices.PythonEngine
     {
+        private bool CONFIG_ENABLE_NET48SHIMCOMPAT = false;
+
         private const string DynamoPrintFuncName = "__dynamoprint__";
         /// <summary> stores a copy of the previously executed code</summary>
         private static string prev_code { get; set; }
@@ -120,7 +122,18 @@ public override object Evaluate(
             if (code != prev_code)
             {
                 ScriptEngine PythonEngine = Python.CreateEngine();
-                if (!string.IsNullOrEmpty(stdLib))
+                //to maintain compatability with ironPython code written in .netframework - we load the system.dll shim
+                //which loads many types which used to be in system.dll(mscorlib) like system.diagnostics.process
+                //which were moved in .Net. These types are now importable by python code without users needing to add
+                //clr.addreference.
+                //TODO consider a preference for this.
+                //TODO test smaller shims...netstd.dll
+
+                if (CONFIG_ENABLE_NET48SHIMCOMPAT)
+                {
+                    PythonEngine.Runtime.LoadAssembly(Assembly.Load("System"));
+                }
+                    if (!string.IsNullOrEmpty(stdLib))
                 {
                     paths = PythonEngine.GetSearchPaths().ToList();
                     paths.Add(stdLib);
@@ -366,5 +379,23 @@ private void OnEvaluationEnd( bool isSuccessful,
 
         #endregion
 
+        internal IronPythonEvaluator(IConfiguration config = null)
+        {
+            //either inject a config or load from appsettings.json
+            if (config is not null)
+            {
+
+            }
+            else
+            {
+                var configPath = Path.Combine(new FileInfo(Assembly.GetExecutingAssembly().Location).DirectoryName, "appsettings.json");
+                config = new ConfigurationBuilder().AddJsonFile(configPath, optional: true).Build();
+            }
+            var enableShimLoad = config.GetSection("config").GetChildren().FirstOrDefault(x => x.Key == nameof(CONFIG_ENABLE_NET48SHIMCOMPAT))?.Value;
+            if (bool.TryParse(enableShimLoad, out var parsed))
+            {
+                CONFIG_ENABLE_NET48SHIMCOMPAT = parsed;
+            }
+        }
     }
 }

DSIronPython/appsettings.json

@@ -0,0 +1,5 @@
+{
+  "config": {
+    "CONFIG_ENABLE_NET48SHIMCOMPAT": "true"
+  }
+}

DSIronPython/pkg.json

@@ -2,7 +2,7 @@
     "license": "",
     "file_hash": null,
     "name": "DynamoIronPython2.7",
-    "version": "3.0.0",
+    "version": "3.1.0",
     "description": "*** This is the official version of the IronPython Extension which will load the IronPython2 evaluation engine for Dynamo. *** \r\n\r\nIf you see the following warning 'The configured Python engine could not be found' when you try to run a Python Script node which is set to use IronPython2, the host application for Dynamo (Such as Revit or Civil 3d) will have chosen to exclude IronPython2 as default installed content and you will need to download this extension in order to enable IronPython2 again.\r\n\r\nYou have the ability to either download this IronPython2 Extension or use the alternative out-of-the-box CPython3 engine and migrate your legacy IronPython2 code to CPython3. While there are differences in language the Python basis is the same and we have provided a Migration Assistant to help you migrate your code to Python3.",
     "group": "",
     "keywords": [ "python", "ironpython" ],

IronPythonExtension/IronPythonExtension.cs

@@ -95,7 +95,7 @@ private static void LoadPythonEngine(Assembly assembly)
         {
             if (assembly == null)
             {
-                return;
+                throw new ArgumentNullException($"Error while loading python engine - assembly {PythonEvaluatorAssembly}.dll was not loaded successfully.");
             }
 
             // Currently we are using try-catch to validate loaded assembly and Singleton Instance method exist