/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.hadoop.hbase.util;
import static org.junit.Assert.assertTrue;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
* Utility class to check whether a given class conforms to builder-style:
* Foo foo =
* new Foo()
* .setBar(bar)
* .setBaz(baz)
*/
public class BuilderStyleTest {
/*
* If a base class Foo declares a method setFoo() returning Foo, then the subclass should
* re-declare the methods overriding the return class with the subclass:
*
* class Foo {
* Foo setFoo() {
* ..
* return this;
* }
* }
*
* class Bar {
* Bar setFoo() {
* return (Bar) super.setFoo();
* }
* }
*
*/
@SuppressWarnings("rawtypes")
public static void assertClassesAreBuilderStyle(Class... classes) {
for (Class clazz : classes) {
System.out.println("Checking " + clazz);
Method[] methods = clazz.getDeclaredMethods();
Map<String, Set<Method>> methodsBySignature = new HashMap<>();
for (Method method : methods) {
if (!Modifier.isPublic(method.getModifiers())) {
continue; // only public classes
}
Class<?> ret = method.getReturnType();
if (method.getName().startsWith("set") || method.getName().startsWith("add")) {
System.out.println(" " + clazz.getSimpleName() + "." + method.getName() + "() : "
+ ret.getSimpleName());
// because of subclass / super class method overrides, we group the methods fitting the
// same signatures because we get two method definitions from java reflection:
// Mutation.setDurability() : Mutation
// Delete.setDurability() : Mutation
// Delete.setDurability() : Delete
String sig = method.getName();
for (Class<?> param : method.getParameterTypes()) {
sig += param.getName();
}
Set<Method> sigMethods = methodsBySignature.get(sig);
if (sigMethods == null) {
sigMethods = new HashSet<>();
methodsBySignature.put(sig, sigMethods);
}
sigMethods.add(method);
}
}
// now iterate over the methods by signatures
for (Map.Entry<String, Set<Method>> e : methodsBySignature.entrySet()) {
// at least one of method sigs should return the declaring class
boolean found = false;
for (Method m : e.getValue()) {
found = clazz.isAssignableFrom(m.getReturnType());
if (found) break;
}
String errorMsg = "All setXXX()|addXX() methods in " + clazz.getSimpleName()
+ " should return a " + clazz.getSimpleName() + " object in builder style. "
+ "Offending method:" + e.getValue().iterator().next().getName();
assertTrue(errorMsg, found);
}
}
}
}