src/java_tools/junitrunner/java/com/google/testing/junit/runner/junit4/JUnit4RunnerBaseModule.java

// Copyright 2012 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.testing.junit.runner.junit4;

import static com.google.inject.multibindings.Multibinder.newSetBinder;
import static com.google.testing.junit.runner.sharding.ShardingFilters.DEFAULT_SHARDING_STRATEGY;

import com.google.common.base.Supplier;
import com.google.common.base.Suppliers;
import com.google.inject.AbstractModule;
import com.google.inject.Key;
import com.google.inject.Provides;
import com.google.inject.Singleton;
import com.google.inject.multibindings.Multibinder;
import com.google.testing.junit.junit4.runner.MemoizingRequest;
import com.google.testing.junit.runner.internal.Stdout;
import com.google.testing.junit.runner.model.TestSuiteModel;
import com.google.testing.junit.runner.sharding.api.ShardingFilterFactory;

import org.junit.internal.TextListener;
import org.junit.runner.Request;
import org.junit.runner.notification.RunListener;

import java.io.OutputStream;
import java.io.PrintStream;
import java.io.UnsupportedEncodingException;
import java.nio.charset.StandardCharsets;

/**
 * Guice module for creating {@link JUnit4Runner}. This contains the common
 * bindings used when either the runner runs actual tests or when we do
 * integration tests of the runner itself.
 *
 * <p>Note: we do not use {@code Modules.override()} to test the runner because
 * there are bindings that we use when the runner runs actual tests that set
 * global state, and we don't want to do that when we test the runner itself.
 */
class JUnit4RunnerBaseModule extends AbstractModule {
  private final Class<?> suiteClass;

  public JUnit4RunnerBaseModule(Class<?> suiteClass) {
    this.suiteClass = suiteClass;
  }

  @Override
  protected void configure() {
    requireBinding(Key.get(PrintStream.class, Stdout.class));
    requireBinding(JUnit4Config.class);
    requireBinding(TestSuiteModel.Builder.class);

    // We require explicit bindings so we don't use an unexpected just-in-time binding
    bind(JUnit4Runner.class);
    bind(JUnit4TestModelBuilder.class);
    bind(CancellableRequestFactory.class);

    // Normal bindings
    bind(ShardingFilterFactory.class).toInstance(DEFAULT_SHARDING_STRATEGY);
    bindConstant().annotatedWith(TopLevelSuite.class).to(suiteClass.getCanonicalName());

    // Bind listeners
    Multibinder<RunListener> listenerBinder = newSetBinder(binder(), RunListener.class);
    listenerBinder.addBinding().to(TextListener.class);
  }

  @Provides @Singleton
  Supplier<TestSuiteModel> provideTestSuiteModelSupplier(JUnit4TestModelBuilder builder) {
    return Suppliers.memoize(builder);
  }

  @Provides @Singleton
  TextListener provideTextListener(@Stdout PrintStream testRunnerOut) {
    return new TextListener(asUtf8PrintStream(testRunnerOut));
  }

  private static PrintStream asUtf8PrintStream(OutputStream stream) {
    try {
      return new PrintStream(stream, false /* autoFlush */, StandardCharsets.UTF_8.toString());
    } catch (UnsupportedEncodingException e) {
      throw new IllegalStateException("UTF-8 must be supported as per the java language spec", e);
    }
  }

  @Provides @Singleton
  Request provideRequest() {
    /*
     * JUnit4Runner requests the Runner twice, once to build the model (before
     * filtering) and once to run the tests (after filtering). Constructing the
     * Runner can be expensive, so Memoize the Runner.
     */
    Request request = Request.aClass(suiteClass);
    return new MemoizingRequest(request);
  }
}