Add StubMethodAdapterTest

This tests the bugfix in StubMethodAdapter made in the change with id
I098996e43e330e995d33f12df1c16355bbc02f0f (commit 491523d)

Change-Id: I1ac897a49071dd9558bdc6b8abec29df913a6047
diff --git a/tools/layoutlib/create/tests/com/android/tools/layoutlib/create/DelegateClassAdapterTest.java b/tools/layoutlib/create/tests/com/android/tools/layoutlib/create/DelegateClassAdapterTest.java
index 0912fb1..afaa399 100644
--- a/tools/layoutlib/create/tests/com/android/tools/layoutlib/create/DelegateClassAdapterTest.java
+++ b/tools/layoutlib/create/tests/com/android/tools/layoutlib/create/DelegateClassAdapterTest.java
@@ -53,12 +53,10 @@
 
     private MockLog mLog;
 
-    private static final String NATIVE_CLASS_NAME = ClassWithNative.class.getCanonicalName();
-    private static final String OUTER_CLASS_NAME = OuterClass.class.getCanonicalName();
-    private static final String INNER_CLASS_NAME = OuterClass.class.getCanonicalName() + "$" +
-                                                   InnerClass.class.getSimpleName();
-    private static final String STATIC_INNER_CLASS_NAME =
-            OuterClass.class.getCanonicalName() + "$" + StaticInnerClass.class.getSimpleName();
+    private static final String NATIVE_CLASS_NAME = ClassWithNative.class.getName();
+    private static final String OUTER_CLASS_NAME = OuterClass.class.getName();
+    private static final String INNER_CLASS_NAME = InnerClass.class.getName();
+    private static final String STATIC_INNER_CLASS_NAME = StaticInnerClass.class.getName();
 
     @Before
     public void setUp() throws Exception {
@@ -69,12 +67,12 @@
     /**
      * Tests that a class not being modified still works.
      */
-    @SuppressWarnings("unchecked")
     @Test
     public void testNoOp() throws Throwable {
         // create an instance of the class that will be modified
         // (load the class in a distinct class loader so that we can trash its definition later)
         ClassLoader cl1 = new ClassLoader(this.getClass().getClassLoader()) { };
+        @SuppressWarnings("unchecked")
         Class<ClassWithNative> clazz1 = (Class<ClassWithNative>) cl1.loadClass(NATIVE_CLASS_NAME);
         ClassWithNative instance1 = clazz1.newInstance();
         assertEquals(42, instance1.add(20, 22));
diff --git a/tools/layoutlib/create/tests/com/android/tools/layoutlib/create/StubMethodAdapterTest.java b/tools/layoutlib/create/tests/com/android/tools/layoutlib/create/StubMethodAdapterTest.java
new file mode 100644
index 0000000..3db3e23
--- /dev/null
+++ b/tools/layoutlib/create/tests/com/android/tools/layoutlib/create/StubMethodAdapterTest.java
@@ -0,0 +1,132 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * 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.android.tools.layoutlib.create;
+
+import com.android.tools.layoutlib.create.dataclass.StubClass;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.objectweb.asm.ClassReader;
+import org.objectweb.asm.ClassVisitor;
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.MethodVisitor;
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.Type;
+
+import java.lang.reflect.Method;
+import java.util.function.BiPredicate;
+import java.util.function.Consumer;
+
+import static org.junit.Assert.*;
+
+public class StubMethodAdapterTest {
+
+    private static final String STUB_CLASS_NAME = StubClass.class.getName();
+
+    /**
+     * Load a dummy class, stub one of its method and ensure that the modified class works as
+     * intended.
+     */
+    @Test
+    public void testBoolean() throws Exception {
+        final String methodName = "returnTrue";
+        // First don't change the method and assert that it returns true
+        testBoolean((name, type) -> false, Assert::assertTrue, methodName);
+        // Change the method now and assert that it returns false.
+        testBoolean((name, type) -> methodName.equals(name) &&
+                Type.BOOLEAN_TYPE.equals(type.getReturnType()), Assert::assertFalse, methodName);
+    }
+
+    /**
+     * @param methodPredicate tests if the method should be replaced
+     */
+    private void testBoolean(BiPredicate<String, Type> methodPredicate, Consumer<Boolean> assertion,
+            String methodName) throws Exception {
+        ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS);
+        // Always rename the class to avoid conflict with the original class.
+        String newClassName = STUB_CLASS_NAME + '_';
+        new ClassReader(STUB_CLASS_NAME).accept(
+                new ClassAdapter(newClassName, writer, methodPredicate), 0);
+        MyClassLoader myClassLoader = new MyClassLoader(newClassName, writer.toByteArray());
+        Class<?> aClass = myClassLoader.loadClass(newClassName);
+        assertTrue("StubClass not loaded by the classloader. Likely a bug in the test.",
+                myClassLoader.findClassCalled);
+        Method method = aClass.getMethod(methodName);
+        Object o = aClass.newInstance();
+        assertion.accept((Boolean) method.invoke(o));
+    }
+
+    private static class ClassAdapter extends ClassVisitor {
+
+        private final String mClassName;
+        private final BiPredicate<String, Type> mMethodPredicate;
+
+        private ClassAdapter(String className, ClassVisitor cv,
+                BiPredicate<String, Type> methodPredicate) {
+            super(Main.ASM_VERSION, cv);
+            mClassName = className.replace('.', '/');
+            mMethodPredicate = methodPredicate;
+        }
+
+        @Override
+        public void visit(int version, int access, String name, String signature, String superName,
+                String[] interfaces) {
+            super.visit(version, access, mClassName, signature, superName,
+                    interfaces);
+        }
+
+        @Override
+        public MethodVisitor visitMethod(int access, String name, String desc, String signature,
+                String[] exceptions) {
+            // Copied partly from
+            // com.android.tools.layoutlib.create.DelegateClassAdapter.visitMethod()
+            // but not generating the _Original method.
+            boolean isStatic = (access & Opcodes.ACC_STATIC) != 0;
+            boolean isNative = (access & Opcodes.ACC_NATIVE) != 0;
+            MethodVisitor originalMethod =
+                    super.visitMethod(access, name, desc, signature, exceptions);
+            Type descriptor = Type.getMethodType(desc);
+            if (mMethodPredicate.test(name, descriptor)) {
+                String methodSignature = mClassName + "#" + name;
+                String invokeSignature = methodSignature + desc;
+                return new StubMethodAdapter(originalMethod, name, descriptor.getReturnType(),
+                        invokeSignature, isStatic, isNative);
+            }
+            return originalMethod;
+        }
+    }
+
+    private static class MyClassLoader extends ClassLoader {
+        private final String mName;
+        private final byte[] mBytes;
+        private boolean findClassCalled;
+
+        private MyClassLoader(String name, byte[] bytes) {
+            mName = name;
+            mBytes = bytes;
+        }
+
+        @Override
+        protected Class<?> findClass(String name) throws ClassNotFoundException {
+            if (name.equals(mName)) {
+                findClassCalled = true;
+                return defineClass(name, mBytes, 0, mBytes.length);
+            }
+            return super.findClass(name);
+        }
+    }
+}
diff --git a/tools/layoutlib/create/tests/com/android/tools/layoutlib/create/dataclass/StubClass.java b/tools/layoutlib/create/tests/com/android/tools/layoutlib/create/dataclass/StubClass.java
new file mode 100644
index 0000000..3ae8e47
--- /dev/null
+++ b/tools/layoutlib/create/tests/com/android/tools/layoutlib/create/dataclass/StubClass.java
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * 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.android.tools.layoutlib.create.dataclass;
+
+import com.android.tools.layoutlib.create.StubMethodAdapterTest;
+
+/**
+ * Used by {@link StubMethodAdapterTest}
+ */
+@SuppressWarnings("unused")
+public class StubClass {
+
+    public boolean returnTrue() {
+        return true;
+    }
+}