1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.tools.layoutlib.create;
18
19import com.android.tools.layoutlib.create.dataclass.StubClass;
20
21import org.junit.Assert;
22import org.junit.Test;
23import org.objectweb.asm.ClassReader;
24import org.objectweb.asm.ClassVisitor;
25import org.objectweb.asm.ClassWriter;
26import org.objectweb.asm.MethodVisitor;
27import org.objectweb.asm.Opcodes;
28import org.objectweb.asm.Type;
29
30import java.lang.reflect.Method;
31import java.util.function.BiPredicate;
32import java.util.function.Consumer;
33
34import static org.junit.Assert.*;
35
36public class StubMethodAdapterTest {
37
38    private static final String STUB_CLASS_NAME = StubClass.class.getName();
39
40    /**
41     * Load a dummy class, stub one of its method and ensure that the modified class works as
42     * intended.
43     */
44    @Test
45    public void testBoolean() throws Exception {
46        final String methodName = "returnTrue";
47        // First don't change the method and assert that it returns true
48        testBoolean((name, type) -> false, Assert::assertTrue, methodName);
49        // Change the method now and assert that it returns false.
50        testBoolean((name, type) -> methodName.equals(name) &&
51                Type.BOOLEAN_TYPE.equals(type.getReturnType()), Assert::assertFalse, methodName);
52    }
53
54    /**
55     * @param methodPredicate tests if the method should be replaced
56     */
57    private void testBoolean(BiPredicate<String, Type> methodPredicate, Consumer<Boolean> assertion,
58            String methodName) throws Exception {
59        ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS);
60        // Always rename the class to avoid conflict with the original class.
61        String newClassName = STUB_CLASS_NAME + '_';
62        new ClassReader(STUB_CLASS_NAME).accept(
63                new ClassAdapter(newClassName, writer, methodPredicate), 0);
64        MyClassLoader myClassLoader = new MyClassLoader(newClassName, writer.toByteArray());
65        Class<?> aClass = myClassLoader.loadClass(newClassName);
66        assertTrue("StubClass not loaded by the classloader. Likely a bug in the test.",
67                myClassLoader.findClassCalled);
68        Method method = aClass.getMethod(methodName);
69        Object o = aClass.newInstance();
70        assertion.accept((Boolean) method.invoke(o));
71    }
72
73    private static class ClassAdapter extends ClassVisitor {
74
75        private final String mClassName;
76        private final BiPredicate<String, Type> mMethodPredicate;
77
78        private ClassAdapter(String className, ClassVisitor cv,
79                BiPredicate<String, Type> methodPredicate) {
80            super(Main.ASM_VERSION, cv);
81            mClassName = className.replace('.', '/');
82            mMethodPredicate = methodPredicate;
83        }
84
85        @Override
86        public void visit(int version, int access, String name, String signature, String superName,
87                String[] interfaces) {
88            super.visit(version, access, mClassName, signature, superName,
89                    interfaces);
90        }
91
92        @Override
93        public MethodVisitor visitMethod(int access, String name, String desc, String signature,
94                String[] exceptions) {
95            // Copied partly from
96            // com.android.tools.layoutlib.create.DelegateClassAdapter.visitMethod()
97            // but not generating the _Original method.
98            boolean isStatic = (access & Opcodes.ACC_STATIC) != 0;
99            boolean isNative = (access & Opcodes.ACC_NATIVE) != 0;
100            MethodVisitor originalMethod =
101                    super.visitMethod(access, name, desc, signature, exceptions);
102            Type descriptor = Type.getMethodType(desc);
103            if (mMethodPredicate.test(name, descriptor)) {
104                String methodSignature = mClassName + "#" + name;
105                String invokeSignature = methodSignature + desc;
106                return new StubMethodAdapter(originalMethod, name, descriptor.getReturnType(),
107                        invokeSignature, isStatic, isNative);
108            }
109            return originalMethod;
110        }
111    }
112
113    private static class MyClassLoader extends ClassLoader {
114        private final String mName;
115        private final byte[] mBytes;
116        private boolean findClassCalled;
117
118        private MyClassLoader(String name, byte[] bytes) {
119            mName = name;
120            mBytes = bytes;
121        }
122
123        @Override
124        protected Class<?> findClass(String name) throws ClassNotFoundException {
125            if (name.equals(mName)) {
126                findClassCalled = true;
127                return defineClass(name, mBytes, 0, mBytes.length);
128            }
129            return super.findClass(name);
130        }
131    }
132}
133