Extracted method finding during discovery into MethodFinder object.

junit5-engine/src/main/java/org/junit/gen5/engine/junit5/discovery/JUnit5TestableFactory.java

@@ -16,6 +16,7 @@
 import java.lang.reflect.Method;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Optional;
 import java.util.logging.Logger;
 import java.util.stream.Collectors;
 
@@ -115,33 +116,8 @@ private JUnit5Testable createTestable(UniqueId uniqueId, UniqueId engineId, List
 	}
 
 	private Method findMethod(String methodSpecPart, Class<?> clazz, UniqueId uniqueId) {
-		// TODO Throw IAE when format wrong. Currently you get IndexOutOfBoundsException.
-		int startParams = methodSpecPart.indexOf('(');
-		String methodName = methodSpecPart.substring(0, startParams);
-		int endParams = methodSpecPart.lastIndexOf(')');
-		String paramsPart = methodSpecPart.substring(startParams + 1, endParams);
-		Class<?>[] parameterTypes = resolveParameterTypes(paramsPart, uniqueId);
-		return findMethod(clazz, methodName, parameterTypes);
-	}
-
-	private Class<?>[] resolveParameterTypes(String paramsPart, UniqueId uniqueId) {
-		if (paramsPart.isEmpty()) {
-			return new Class<?>[0];
-		}
-
-		// @formatter:off
-		List<Class<?>> types = Arrays.stream(paramsPart.split(","))
-				.map(className -> loadRequiredParamterClass(className, uniqueId, paramsPart))
-				.collect(Collectors.toList());
-		// @formatter:on
-
-		return types.toArray(new Class<?>[types.size()]);
-	}
-
-	private Method findMethod(Class<?> clazz, String methodName, Class<?>[] parameterTypes) {
-		return ReflectionUtils.findMethod(clazz, methodName, parameterTypes).orElseThrow(
-			() -> new PreconditionViolationException(String.format("No method with name '%s' and parameter types '%s'",
-				methodName, StringUtils.nullSafeToString(parameterTypes))));
+		Optional<Method> optionalMethod = new MethodFinder().findMethod(methodSpecPart, clazz);
+		return optionalMethod.orElseThrow(() -> createCannotResolveUniqueIdException(uniqueId, methodSpecPart));
 	}
 
 	private Class<?> findNestedClass(String nameExtension, Class<?> containerClass) {
@@ -162,11 +138,6 @@ private Class<?> loadClassByName(String className) {
 			() -> new PreconditionViolationException(String.format("Cannot load class '%s'", className)));
 	}
 
-	private Class<?> loadRequiredParamterClass(String className, UniqueId fullUniqueId, String paramsPart) {
-		return ReflectionUtils.loadClass(className).orElseThrow(
-			() -> createCannotResolveUniqueIdException(fullUniqueId, paramsPart));
-	}
-
 	private static RuntimeException createCannotResolveUniqueIdException(UniqueId fullUniqueId, String uniqueIdPart) {
 		return new PreconditionViolationException(
 			String.format("Cannot resolve part '%s' of unique ID '%s'", uniqueIdPart, fullUniqueId.getUniqueString()));

junit5-engine/src/main/java/org/junit/gen5/engine/junit5/discovery/MethodFinder.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2015-2016 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.discovery;
+
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+import org.junit.gen5.commons.util.PreconditionViolationException;
+import org.junit.gen5.commons.util.ReflectionUtils;
+import org.junit.gen5.engine.UniqueId;
+
+public class MethodFinder {
+
+	public Optional<Method> findMethod(String methodSpecPart, Class<?> clazz) {
+		try {
+
+			// TODO Throw IAE when format wrong. Currently you get IndexOutOfBoundsException.
+			int startParams = methodSpecPart.indexOf('(');
+			String methodName = methodSpecPart.substring(0, startParams);
+			int endParams = methodSpecPart.lastIndexOf(')');
+			String paramsPart = methodSpecPart.substring(startParams + 1, endParams);
+			Class<?>[] parameterTypes = resolveParameterTypes(paramsPart);
+			return findMethod(clazz, methodName, parameterTypes);
+		}
+		catch (RuntimeException rte) {
+			return Optional.empty();
+		}
+	}
+
+	private Class<?>[] resolveParameterTypes(String paramsPart) {
+		if (paramsPart.isEmpty()) {
+			return new Class<?>[0];
+		}
+
+		// @formatter:off
+		List<Class<?>> types = Arrays.stream(paramsPart.split(","))
+				.map(className -> loadRequiredParameterClass(className))
+				.collect(Collectors.toList());
+		// @formatter:on
+
+		return types.toArray(new Class<?>[types.size()]);
+	}
+
+	private Optional<Method> findMethod(Class<?> clazz, String methodName, Class<?>[] parameterTypes) {
+		return ReflectionUtils.findMethod(clazz, methodName, parameterTypes);
+	}
+
+	private Class<?> loadRequiredParameterClass(String className) {
+		return ReflectionUtils.loadClass(className).orElseThrow(() -> new RuntimeException("Not found: " + className));
+	}
+
+	private static RuntimeException createCannotResolveUniqueIdException(UniqueId fullUniqueId, String uniqueIdPart) {
+		return new PreconditionViolationException(
+			String.format("Cannot resolve part '%s' of unique ID '%s'", uniqueIdPart, fullUniqueId.getUniqueString()));
+	}
+
+}