src/test/java/com/android/tools/r8/shaking/assumenosideeffects/AssumeNoSideEffectsForLibraryMethodTest.java

// Copyright (c) 2020, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

package com.android.tools.r8.shaking.assumenosideeffects;

import static com.android.tools.r8.utils.codeinspector.Matchers.isPresent;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.junit.Assert.assertTrue;

import com.android.tools.r8.TestBase;
import com.android.tools.r8.TestParameters;
import com.android.tools.r8.TestParametersCollection;
import com.android.tools.r8.utils.codeinspector.MethodSubject;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;

@RunWith(Parameterized.class)
public class AssumeNoSideEffectsForLibraryMethodTest extends TestBase {

  private final TestParameters parameters;

  @Parameters(name = "{0}")
  public static TestParametersCollection data() {
    return getTestParameters().withAllRuntimesAndApiLevels().build();
  }

  public AssumeNoSideEffectsForLibraryMethodTest(TestParameters parameters) {
    this.parameters = parameters;
  }

  @Test
  public void test() throws Exception {
    testForR8(parameters.getBackend())
        .addProgramClasses(TestClass.class)
        .addKeepMainRule(TestClass.class)
        .addKeepRules("-assumenosideeffects class java.lang.Object { int hashCode() return 42; }")
        .setMinApi(parameters.getApiLevel())
        .compile()
        .inspect(
            inspector -> {
              MethodSubject mainMethodSubject = inspector.clazz(TestClass.class).mainMethod();
              assertThat(mainMethodSubject, isPresent());
              assertTrue(
                  mainMethodSubject
                      .streamInstructions()
                      .noneMatch(
                          instruction ->
                              instruction.isInvokeVirtual()
                                  && instruction.getMethod().name.toString().equals("hashCode")));
            })
        .run(parameters.getRuntime(), TestClass.class)
        .assertSuccessWithOutputLines("42");
  }

  static class TestClass {

    public static void main(String[] args) {
      System.out.println(new Object().hashCode());
    }
  }
}