com.google.devtools.build.android.desugar.Java7CompatibilityTest.java Source code

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Here is the source code for com.google.devtools.build.android.desugar.Java7CompatibilityTest.java

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// Copyright 2016 The Bazel Authors. All rights reserved.
//
// 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.google.devtools.build.android.desugar;

import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.fail;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

@RunWith(JUnit4.class)
public class Java7CompatibilityTest {

    @Test
    public void testJava7CompatibleInterface() throws Exception {
        ClassReader reader = new ClassReader(ExtendsDefault.class.getName());
        ClassTester tester = new ClassTester();
        reader.accept(new Java7Compatibility(tester, null, null), 0);
        assertThat(tester.version).isEqualTo(Opcodes.V1_7);
        assertThat(tester.bridgeMethods).isEqualTo(0); // make sure we strip bridge methods
        assertThat(tester.clinitMethods).isEqualTo(1); // make sure we don't strip <clinit>
    }

    @Test
    public void testDefaultMethodFails() throws Exception {
        ClassReader reader = new ClassReader(WithDefault.class.getName());
        try {
            reader.accept(new Java7Compatibility(null, null, null), 0);
            fail("IllegalArgumentException expected");
        } catch (IllegalArgumentException expected) {
            assertThat(expected).hasMessageThat().contains("getVersion()I");
        }
    }

    /**
     * Tests that a class implementing interfaces with bridge methods redeclares those bridges.
     * This is behavior of javac that we rely on.
     */
    @Test
    public void testConcreteClassRedeclaresBridges() throws Exception {
        ClassReader reader = new ClassReader(Impl.class.getName());
        ClassTester tester = new ClassTester();
        reader.accept(new Java7Compatibility(tester, null, null), 0);
        assertThat(tester.version).isEqualTo(Opcodes.V1_7);
        assertThat(tester.bridgeMethods).isEqualTo(2);
    }

    private static class ClassTester extends ClassVisitor {

        int version;
        int bridgeMethods;
        int clinitMethods;

        private ClassTester() {
            super(Opcodes.ASM5, null);
        }

        @Override
        public void visit(int version, int access, String name, String signature, String superName,
                String[] interfaces) {
            this.version = version;
            super.visit(version, access, name, signature, superName, interfaces);
        }

        @Override
        public MethodVisitor visitMethod(int access, String name, String desc, String signature,
                String[] exceptions) {
            if (BitFlags.isSet(access, Opcodes.ACC_BRIDGE)) {
                ++bridgeMethods;
            }
            if ("<clinit>".equals(name)) {
                ++clinitMethods;
            }
            return super.visitMethod(access, name, desc, signature, exceptions);
        }
    }

    interface WithDefault<T> {
        default int getVersion() {
            return 18;
        }

        T get();
    }

    // Javac will generate a default bridge method "Object get()" that Java7Compatibility will remove
    interface ExtendsDefault<T extends Number> extends WithDefault<T> {
        public static final Integer X = Integer.valueOf(37);

        String name();

        @Override
        T get();
    }

    // Javac will generate 2 bridge methods that we *don't* want to remove
    static class Impl implements ExtendsDefault<Integer> {
        @Override
        public Integer get() {
            return X;
        }

        @Override
        public String name() {
            return "test";
        }
    }
}