extracted interface for resolver registry

some todo comments

junit5-engine/src/main/java/org/junit/gen5/engine/junit5/execution/injection/MethodArgumentResolverEngine.java

@@ -18,7 +18,8 @@
 // for a 'real' solution see: org.springframework.web.method.support.HandlerMethodArgumentResolver
 public class MethodArgumentResolverEngine {
 
-	PrimitiveMethodArgumentResolverRegistry resolverRegistry = new PrimitiveMethodArgumentResolverRegistry();
+	//todo: when introducing the extension mechanism this instance will have to come from outside
+	MethodArgumentResolverRegistry resolverRegistry = new PrimitiveMethodArgumentResolverRegistry();
 
 	/**
 	 * prepare a list of objects as arguments for the execution of this test method
@@ -52,6 +53,7 @@ public List<Object> prepareArguments(MethodTestDescriptor methodTestDescriptor)
 	private Object resolveArgumentForMethodParameter(Parameter parameter)
 			throws NoSuchMethodException, InstantiationException, IllegalAccessException, InvocationTargetException {
 
+		//todo: throw exception as well when there are more than 1 resolver for a given parameter
 		for (MethodArgumentResolver argumentResolver : this.resolverRegistry.getMethodArgumentResolvers()) {
 			if (argumentResolver.supports(parameter))
 				return argumentResolver.resolveArgumentForMethodParameter(parameter);

junit5-engine/src/main/java/org/junit/gen5/engine/junit5/execution/injection/MethodArgumentResolverRegistry.java

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v1.0 which
+ * accompanies this distribution and is available at
+ *
+ * http://www.eclipse.org/legal/epl-v10.html
+ */
+
+package org.junit.gen5.engine.junit5.execution.injection;
+
+import java.util.*;
+
+/**
+ * Created by mmerdes on 07.11.15.
+ */
+public interface MethodArgumentResolverRegistry {
+
+	List<MethodArgumentResolver> getMethodArgumentResolvers();
+}

junit5-engine/src/main/java/org/junit/gen5/engine/junit5/execution/injection/PrimitiveMethodArgumentResolverRegistry.java

@@ -13,11 +13,12 @@
 import java.util.*;
 
 //TODO: this class will have to be filled by the extension mechanism and handed to the resolver engine from outside
-public class PrimitiveMethodArgumentResolverRegistry {
+public class PrimitiveMethodArgumentResolverRegistry implements MethodArgumentResolverRegistry {
 
 	private List<MethodArgumentResolver> methodArgumentResolvers = Arrays.asList(
 		new SimpleTypeBasedMethodArgumentResolver(), new SimpleAnnotationBasedMethodArgumentResolver());
 
+	@Override
 	public List<MethodArgumentResolver> getMethodArgumentResolvers() {
 		return this.methodArgumentResolvers;
 	}