diff --git a/platform/core-impl/src/com/intellij/openapi/components/impl/ComponentManagerImpl.java b/platform/core-impl/src/com/intellij/openapi/components/impl/ComponentManagerImpl.java
index c83c3ccdfaab..d16019714a17 100644
--- a/platform/core-impl/src/com/intellij/openapi/components/impl/ComponentManagerImpl.java
+++ b/platform/core-impl/src/com/intellij/openapi/components/impl/ComponentManagerImpl.java
@@ -212,19 +212,12 @@ public abstract class ComponentManagerImpl extends UserDataHolderBase implements
   public synchronized <T> T registerComponentInstance(@NotNull Class<T> componentKey, @NotNull T componentImplementation) {
     MutablePicoContainer picoContainer = getPicoContainer();
     ComponentAdapter adapter = picoContainer.getComponentAdapter(componentKey);
-    if (adapter instanceof ComponentConfigComponentAdapter) {
-      ComponentConfigComponentAdapter componentAdapter = (ComponentConfigComponentAdapter)adapter;
-      Object oldInstance = componentAdapter.myInitializedComponentInstance;
-      // we don't update pluginId - method is test only
-      componentAdapter.myInitializedComponentInstance = componentImplementation;
-      return (T)oldInstance;
-    }
-    else {
-      // todo it seems, it is unrealistic (illegal) case - component must have our adapter
-      picoContainer.unregisterComponent(componentKey);
-      picoContainer.registerComponentInstance(componentKey, componentImplementation);
-      return null;
-    }
+    LOG.assertTrue(adapter instanceof ComponentConfigComponentAdapter);
+    ComponentConfigComponentAdapter componentAdapter = (ComponentConfigComponentAdapter)adapter;
+    Object oldInstance = componentAdapter.myInitializedComponentInstance;
+    // we don't update pluginId - method is test only
+    componentAdapter.myInitializedComponentInstance = componentImplementation;
+    return (T)oldInstance;
   }
 
   @Override
diff --git a/platform/platform-impl/src/com/intellij/openapi/components/service.kt b/platform/platform-impl/src/com/intellij/openapi/components/service.kt
index 247b0cf2d085..f8757e54d1f8 100644
--- a/platform/platform-impl/src/com/intellij/openapi/components/service.kt
+++ b/platform/platform-impl/src/com/intellij/openapi/components/service.kt
@@ -26,4 +26,4 @@ public inline fun <reified T: Any> Project.service(): T? = ServiceManager.getSer
 public val ComponentManager.stateStore: IComponentStore
   get() = getPicoContainer().getComponentInstance(javaClass<IComponentStore>()) as IComponentStore
 
-public fun <T> ComponentManager.getComponents(baseClass: Class<T>): List<T> = (this as ComponentManagerEx).getComponentInstancesOfType(baseClass)
+public fun <T> ComponentManager.getComponents(baseClass: Class<T>): List<T> = (this as ComponentManagerEx).getComponentInstancesOfType(baseClass)
\ No newline at end of file
diff --git a/platform/testFramework/testSrc/com/intellij/testFramework/util.kt b/platform/testFramework/testSrc/com/intellij/testFramework/util.kt
new file mode 100644
index 000000000000..a68c9d3b73ef
--- /dev/null
+++ b/platform/testFramework/testSrc/com/intellij/testFramework/util.kt
@@ -0,0 +1,26 @@
+/*
+ * Copyright 2000-2015 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.testFramework
+
+import com.intellij.openapi.components.ComponentManager
+import org.picocontainer.MutablePicoContainer
+
+public fun <T> ComponentManager.registerServiceInstance(interfaceClass: Class<T>, instance: T) {
+  val picoContainer = getPicoContainer() as MutablePicoContainer
+  val key = interfaceClass.getName()
+  picoContainer.unregisterComponent(key)
+  picoContainer.registerComponentInstance(key, instance)
+}
\ No newline at end of file