TestScope.java

/*
 * Copyright 2014 Google Inc. 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.acai;

import static com.google.common.base.Preconditions.checkState;

import com.google.inject.AbstractModule;
import com.google.inject.Key;
import com.google.inject.OutOfScopeException;
import com.google.inject.Provider;
import com.google.inject.Scope;
import java.util.HashMap;
import java.util.Map;

/** Scope for bindings annotated with {@link TestScoped}. */
class TestScope implements Scope {
  private final ThreadLocal<Map<Key<?>, Object>> values = new ThreadLocal<>();

  void enter() {
    checkState(values.get() == null, "TestScope is already in progress.");
    values.set(new HashMap<>());
  }

  void exit() {
    checkState(values.get() != null, "TestScope not in progress");
    values.remove();
  }

  @Override
  public <T> Provider<T> scope(final Key<T> key, final Provider<T> unscopedProvider) {
    return () -> {
      Map<Key<?>, Object> scopedObjects = getScopedObjectMap(key);

      @SuppressWarnings("unchecked")
      T scopedObject = (T) scopedObjects.get(key);
      if (scopedObject == null && !scopedObjects.containsKey(key)) {
        scopedObject = unscopedProvider.get();
        scopedObjects.put(key, scopedObject);
      }
      return scopedObject;
    };
  }

  private <T> Map<Key<?>, Object> getScopedObjectMap(Key<T> key) {
    Map<Key<?>, Object> scopedObjects = values.get();
    if (scopedObjects == null) {
      throw new OutOfScopeException("Attempt to inject @TestScoped binding outside test: " + key);
    }
    return scopedObjects;
  }

  static class TestScopeModule extends AbstractModule {
    @Override
    protected void configure() {
      TestScope testScope = new TestScope();
      bind(TestScope.class).annotatedWith(AcaiInternal.class).toInstance(testScope);
      bindScope(TestScoped.class, testScope);
    }
  }
}