src/tools/android/java/com/google/devtools/build/android/desugar/testing/junit/DesugarRule.java

/*
 * Copyright 2019 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.testing.junit;

import com.google.auto.value.AutoAnnotation;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.devtools.build.android.desugar.testing.junit.SourceCompilationUnit.SourceCompilationException;
import java.io.IOException;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodHandles.Lookup;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Parameter;
import org.junit.rules.TestRule;
import org.junit.runner.Description;
import org.junit.runners.model.Statement;

/** A JUnit4 Rule that desugars an input jar file and load the transformed jar to JVM. */
public final class DesugarRule implements TestRule {

  static final ClassLoader BASE_CLASS_LOADER = ClassLoader.getSystemClassLoader().getParent();

  private final Object testInstance;
  private final MethodHandles.Lookup testInstanceLookup;

  private final ImmutableList<Field> injectableFields;
  private final ImmutableList<SourceCompilationUnit> sourceCompilationUnits;
  private final RuntimeEntityResolver runtimeEntityResolver;

  /**
   * The entry point to create a {@link DesugarRule}.
   *
   * @param testInstance The <code>this</code> reference of the JUnit test class.
   * @param testInstanceLookup The lookup object from the test class, i.e.<code>
   *     MethodHandles.lookup()</code>
   */
  public static DesugarRuleBuilder builder(Object testInstance, Lookup testInstanceLookup) {
    return new DesugarRuleBuilder(testInstance, testInstanceLookup);
  }

  DesugarRule(
      Object testInstance,
      Lookup testInstanceLookup,
      ImmutableList<Field> injectableFields,
      ImmutableList<SourceCompilationUnit> sourceCompilationUnits,
      RuntimeEntityResolver runtimeEntityResolver) {
    this.testInstance = testInstance;
    this.testInstanceLookup = testInstanceLookup;
    this.injectableFields = injectableFields;
    this.sourceCompilationUnits = sourceCompilationUnits;
    this.runtimeEntityResolver = runtimeEntityResolver;
  }

  void compileSourceInputs() throws IOException, SourceCompilationException {
    for (SourceCompilationUnit compilationUnit : sourceCompilationUnits) {
      compilationUnit.compile();
    }
  }

  void executeDesugarTransformation() throws Exception {
    runtimeEntityResolver.executeTransformation();
  }

  @Override
  public Statement apply(Statement base, Description description) {
    return base;
  }

  public void injectTestInstanceFields() throws Throwable {
    for (Field field : injectableFields) {
      MethodHandle fieldSetter = testInstanceLookup.unreflectSetter(field);
      fieldSetter.invoke(testInstance, resolve(field, field.getType()));
    }
  }

  ImmutableMap<Parameter, Object> getResolvableParameters(Method method) throws Throwable {
    ImmutableMap.Builder<Parameter, Object> resolvableParameterValues = ImmutableMap.builder();
    for (Parameter parameter : method.getParameters()) {
      if (RuntimeEntityResolver.SUPPORTED_QUALIFIERS.stream()
          .anyMatch(parameter::isAnnotationPresent)) {
        resolvableParameterValues.put(parameter, resolve(parameter, parameter.getType()));
      }
    }
    return resolvableParameterValues.build();
  }

  public <T> T resolve(AnnotatedElement param, Class<T> type) throws Throwable {
    return runtimeEntityResolver.resolve(param, type);
  }

  ImmutableMap<String, Integer> getInputClassFileMajorVersionMap() {
    try {
      return runtimeEntityResolver.getInputClassFileMajorVersions();
    } catch (IOException e) {
      throw new IllegalStateException(e);
    }
  }

  @AutoAnnotation
  static DynamicClassLiteral createDynamicClassLiteral(String value, int round) {
    return new AutoAnnotation_DesugarRule_createDynamicClassLiteral(value, round);
  }
}