Use new EnterContextualReflection API to address .NET Core assembly l…

…oading issues

src/NUnitEngine/nunit.engine.core/Drivers/NUnitNetCore31Driver.cs

@@ -38,6 +38,7 @@ public class NUnitNetCore31Driver : IFrameworkDriver
  Assembly _frameworkAssembly;
  object _frameworkController;
  Type _frameworkControllerType;
+ CustomAssemblyLoadContext _assemblyLoadContext;
 
  /// <summary>
  /// An id prefix that will be passed to the test framework and used as part of the
@@ -56,22 +57,23 @@ public string Load(string assemblyPath, IDictionary<string, object> settings)
  var idPrefix = string.IsNullOrEmpty(ID) ? "" : ID + "-";
 
  assemblyPath = Path.GetFullPath(assemblyPath); //AssemblyLoadContext requires an absolute path
- var assemblyLoadContext = new CustomAssemblyLoadContext(assemblyPath);
+ _assemblyLoadContext = new CustomAssemblyLoadContext(assemblyPath);
+
  try
  {
- _testAssembly = assemblyLoadContext.LoadFromAssemblyPath(assemblyPath);
+ _testAssembly = _assemblyLoadContext.LoadFromAssemblyPath(assemblyPath);
  }
  catch (Exception e)
  {
  throw new NUnitEngineException(string.Format(FAILED_TO_LOAD_TEST_ASSEMBLY, assemblyPath), e);
  }
 
  var nunitRef = _testAssembly.GetReferencedAssemblies().FirstOrDefault(reference => reference.Name.Equals("nunit.framework", StringComparison.OrdinalIgnoreCase));
- 
+
  if (nunitRef == null)
  throw new NUnitEngineException(FAILED_TO_LOAD_NUNIT);
 
- _frameworkAssembly = assemblyLoadContext.LoadFromAssemblyName(nunitRef);
+ _frameworkAssembly = _assemblyLoadContext.LoadFromAssemblyName(nunitRef);
  if (_frameworkAssembly == null)
  throw new NUnitEngineException(FAILED_TO_LOAD_NUNIT);
 
@@ -112,7 +114,7 @@ public string Run(ITestEventListener listener, string filter)
  }
 
  /// <summary>
- /// Executes the tests in an assembly asyncronously.
+ /// Executes the tests in an assembly asynchronously.
  /// </summary>
  /// <param name="callback">A callback that receives XML progress notices</param>
  /// <param name="filter">A filter that controls which tests are executed</param>
@@ -179,7 +181,11 @@ object ExecuteMethod(MethodInfo method, params object[] args)
  {
  throw new NUnitEngineException(INVALID_FRAMEWORK_MESSAGE);
  }
- return method.Invoke(_frameworkController, args);
+
+ using (_assemblyLoadContext.EnterContextualReflection())
+ {
+ return method.Invoke(_frameworkController, args);
+ }
  }
  }
 }