Added option to register custom backends for testing

Duplicati/Library/DynamicLoader/BackendLoader.cs

@@ -183,5 +183,14 @@ namespace Duplicati.Library.DynamicLoader
             return _backendLoader.GetBackend(url, options);
         }
         #endregion
+
+        /// <summary>
+        /// Adds a backend to the loader
+        /// </summary>
+        /// <param name="backend">The backend to add</param>
+        public static void AddBackend(IBackend backend)
+        {
+            _backendLoader.AddModule(backend);
+        }
     }
 }

Duplicati/Library/DynamicLoader/DynamicLoader.cs

@@ -233,5 +233,16 @@ namespace Duplicati.Library.DynamicLoader
                 return m_supportedCommands[type] = item.SupportedCommands.ToList().AsReadOnly();
             }
         }
+
+        /// <summary>
+        /// Helper method to register a module
+        /// </summary>
+        /// <param name="module">The module to register</param>
+        public void AddModule(T module)
+        {
+            LoadInterfaces();
+            lock (m_lock)
+                m_interfaces[GetInterfaceKey(module)] = module;
+        }
     }
 }

Duplicati/UnitTest/GeneralBlackBoxTesting.cs

@@ -147,6 +147,7 @@ namespace Duplicati.UnitTest
             var u = new Library.Utility.Uri(TestUtils.GetDefaultTarget());
             RandomErrorBackend.WrappedBackend = u.Scheme;
             var target = u.SetScheme(new RandomErrorBackend().ProtocolKey).ToString();
+            Library.DynamicLoader.BackendLoader.AddBackend(new RandomErrorBackend());
 
             SVNCheckoutTest.RunTest(TestFolders.Take(5).ToArray(), TestOptions, target);
         }
@@ -158,6 +159,7 @@ namespace Duplicati.UnitTest
             var u = new Library.Utility.Uri(TestUtils.GetDefaultTarget());
             SizeOmittingBackend.WrappedBackend = u.Scheme;
             var target = u.SetScheme(new SizeOmittingBackend().ProtocolKey).ToString();
+            Library.DynamicLoader.BackendLoader.AddBackend(new SizeOmittingBackend());
 
             SVNCheckoutTest.RunTest(TestFolders.Take(5).ToArray(), TestOptions, target);
         }