guice/core/test/com/google/inject/CircularDependencyTest.java

/*
 * Copyright (C) 2006 Google Inc.
 *
 * 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.inject;

import static com.google.inject.Asserts.assertContains;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

import com.google.common.collect.Maps;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import junit.framework.TestCase;

/**
 * @author crazybob@google.com (Bob Lee)
 * @author sameb@google.com (Sam Berlin)
 */
public class CircularDependencyTest extends TestCase {

  @Override
  protected void setUp() throws Exception {
    AImpl.nextId = 0;
    BImpl.nextId = 0;
  }

  public void testCircularlyDependentConstructors() throws CreationException {
    Injector injector =
        Guice.createInjector(
            new AbstractModule() {
              @Override
              protected void configure() {
                bind(A.class).to(AImpl.class);
                bind(B.class).to(BImpl.class);
              }
            });
    assertCircularDependencies(injector);
  }

  public void testCircularlyDependentConstructorsWithProviderMethods() throws CreationException {
    Injector injector =
        Guice.createInjector(
            new AbstractModule() {

              @Provides
              @Singleton
              A a(B b) {
                return new AImpl(b);
              }

              @Provides
              B b(A a) {
                return new BImpl(a);
              }
            });
    assertCircularDependencies(injector);
  }

  public void testCircularlyDependentConstructorsWithProviderInstances() throws CreationException {
    Injector injector =
        Guice.createInjector(
            new AbstractModule() {
              @Override
              protected void configure() {
                bind(A.class)
                    .toProvider(
                        new Provider<A>() {
                          @Inject Provider<B> bp;

                          @Override
                          public A get() {
                            return new AImpl(bp.get());
                          }
                        })
                    .in(Singleton.class);
                bind(B.class)
                    .toProvider(
                        new Provider<B>() {
                          @Inject Provider<A> ap;

                          @Override
                          public B get() {
                            return new BImpl(ap.get());
                          }
                        });
              }
            });
    assertCircularDependencies(injector);
  }

  public void testCircularlyDependentConstructorsWithProviderKeys() throws CreationException {
    Injector injector =
        Guice.createInjector(
            new AbstractModule() {
              @Override
              protected void configure() {
                bind(A.class).toProvider(AP.class).in(Singleton.class);
                bind(B.class).toProvider(BP.class);
              }
            });
    assertCircularDependencies(injector);
  }

  public void testCircularlyDependentConstructorsWithProvidedBy() throws CreationException {
    Injector injector = Guice.createInjector();
    assertCircularDependencies(injector);
  }

  private void assertCircularDependencies(Injector injector) {
    A a = injector.getInstance(A.class);
    assertNotNull(a.getB().getA());
    assertEquals(0, a.id());
    assertEquals(a.id(), a.getB().getA().id());
    assertEquals(0, a.getB().id());
    assertEquals(1, AImpl.nextId);
    assertEquals(1, BImpl.nextId);
    assertSame(a, injector.getInstance(A.class));
  }

  @ProvidedBy(AutoAP.class)
  public interface A {
    B getB();

    int id();
  }

  @Singleton
  static class AImpl implements A {
    static int nextId;
    int id = nextId++;

    final B b;

    @Inject
    public AImpl(B b) {
      this.b = b;
    }

    @Override
    public int id() {
      return id;
    }

    @Override
    public B getB() {
      return b;
    }
  }

  static class AP implements Provider<A> {
    @Inject Provider<B> bp;

    @Override
    public A get() {
      return new AImpl(bp.get());
    }
  }

  @Singleton
  static class AutoAP implements Provider<A> {
    @Inject Provider<B> bp;
    A a;

    @Override
    public A get() {
      if (a == null) {
        a = new AImpl(bp.get());
      }
      return a;
    }
  }

  @ProvidedBy(BP.class)
  public interface B {
    A getA();

    int id();
  }

  static class BImpl implements B {
    static int nextId;
    int id = nextId++;

    final A a;

    @Inject
    public BImpl(A a) {
      this.a = a;
    }

    @Override
    public int id() {
      return id;
    }

    @Override
    public A getA() {
      return a;
    }
  }

  static class BP implements Provider<B> {
    Provider<A> ap;

    @Inject
    BP(Provider<A> ap) {
      this.ap = ap;
    }

    @Override
    public B get() {
      return new BImpl(ap.get());
    }
  }

  public void testUnresolvableCircularDependency() {
    try {
      Guice.createInjector().getInstance(C.class);
      fail();
    } catch (ProvisionException expected) {
      assertContains(
          expected.getMessage(),
          "Tried proxying CircularDependencyTest$C to support a circular dependency, ",
          "but it is not an interface.");
    }
  }

  public void testUnresolvableCircularDependenciesWithProviderInstances() {
    try {
      Guice.createInjector(
              new AbstractModule() {

                @Provides
                C c(D d) {
                  return null;
                }

                @Provides
                D d(C c) {
                  return null;
                }
              })
          .getInstance(C.class);
      fail();
    } catch (ProvisionException expected) {
      assertContains(
          expected.getMessage(),
          "Tried proxying CircularDependencyTest$C to support a circular dependency, ",
          "but it is not an interface.");
    }
  }

  public void testUnresolvableCircularDependenciesWithProviderKeys() {
    try {
      Guice.createInjector(
              new AbstractModule() {
                @Override
                protected void configure() {
                  bind(C2.class).toProvider(C2P.class);
                  bind(D2.class).toProvider(D2P.class);
                }
              })
          .getInstance(C2.class);
      fail();
    } catch (ProvisionException expected) {
      assertContains(
          expected.getMessage(),
          "Tried proxying CircularDependencyTest$C2 to support a circular dependency, ",
          "but it is not an interface.");
    }
  }

  public void testUnresolvableCircularDependenciesWithProvidedBy() {
    try {
      Guice.createInjector().getInstance(C2.class);
      fail();
    } catch (ProvisionException expected) {
      assertContains(
          expected.getMessage(),
          "Tried proxying CircularDependencyTest$C2 to support a circular dependency, ",
          "but it is not an interface.");
    }
  }

  static class C {
    @Inject
    C(D d) {}
  }

  static class D {
    @Inject
    D(C c) {}
  }

  static class C2P implements Provider<C2> {
    @Inject Provider<D2> dp;

    @Override
    public C2 get() {
      dp.get();
      return null;
    }
  }

  static class D2P implements Provider<D2> {
    @Inject Provider<C2> cp;

    @Override
    public D2 get() {
      cp.get();
      return null;
    }
  }

  @ProvidedBy(C2P.class)
  static class C2 {
    @Inject
    C2(D2 d) {}
  }

  @ProvidedBy(D2P.class)
  static class D2 {
    @Inject
    D2(C2 c) {}
  }

  public void testDisabledCircularDependency() {
    try {
      Guice.createInjector(
              new AbstractModule() {
                @Override
                protected void configure() {
                  binder().disableCircularProxies();
                }
              })
          .getInstance(C.class);
      fail();
    } catch (ProvisionException expected) {
      assertContains(
          expected.getMessage(),
          "Found a circular dependency involving CircularDependencyTest$C"
              + ", and circular dependencies are disabled.");
    }
  }

  public void testDisabledCircularDependenciesWithProviderInstances() {
    try {
      Guice.createInjector(
              new AbstractModule() {
                @Override
                protected void configure() {
                  binder().disableCircularProxies();
                }

                @Provides
                C c(D d) {
                  return null;
                }

                @Provides
                D d(C c) {
                  return null;
                }
              })
          .getInstance(C.class);
      fail();
    } catch (ProvisionException expected) {
      assertContains(
          expected.getMessage(),
          "Found a circular dependency involving CircularDependencyTest$C"
              + ", and circular dependencies are disabled.");
    }
  }

  public void testDisabledCircularDependenciesWithProviderKeys() {
    try {
      Guice.createInjector(
              new AbstractModule() {
                @Override
                protected void configure() {
                  binder().disableCircularProxies();
                  bind(C2.class).toProvider(C2P.class);
                  bind(D2.class).toProvider(D2P.class);
                }
              })
          .getInstance(C2.class);
      fail();
    } catch (ProvisionException expected) {
      assertContains(
          expected.getMessage(),
          "Found a circular dependency involving CircularDependencyTest$C2"
              + ", and circular dependencies are disabled.");
    }
  }

  public void testDisabledCircularDependenciesWithProvidedBy() {
    try {
      Guice.createInjector(
              new AbstractModule() {
                @Override
                protected void configure() {
                  binder().disableCircularProxies();
                }
              })
          .getInstance(C2.class);
      fail();
    } catch (ProvisionException expected) {
      assertContains(
          expected.getMessage(),
          "Found a circular dependency involving CircularDependencyTest$C2"
              + ", and circular dependencies are disabled.");
    }
  }

  /**
   * As reported by issue 349, we give a lousy trace when a class is circularly dependent on itself
   * in multiple ways.
   */
  public void testCircularlyDependentMultipleWays() {
    Injector injector =
        Guice.createInjector(
            new AbstractModule() {
              @Override
              protected void configure() {
                binder.bind(A.class).to(E.class);
                binder.bind(B.class).to(E.class);
              }
            });
    injector.getInstance(A.class);
  }

  public void testDisablingCircularDependencies() {
    Injector injector =
        Guice.createInjector(
            new AbstractModule() {
              @Override
              protected void configure() {
                binder().disableCircularProxies();
                binder.bind(A.class).to(E.class);
                binder.bind(B.class).to(E.class);
              }
            });

    try {
      injector.getInstance(A.class);
      fail("expected exception");
    } catch (ProvisionException expected) {
      assertContains(
          expected.getMessage(),
          "Found a circular dependency involving CircularDependencyTest$A, and circular"
              + " dependencies are disabled.");
    }
  }

  @Singleton
  static class E implements A, B {
    @Inject
    public E(A a, B b) {}

    @Override
    public B getB() {
      return this;
    }

    @Override
    public A getA() {
      return this;
    }

    @Override
    public int id() {
      return 0;
    }
  }

  public void testCircularDependencyProxyDelegateNeverInitialized() {
    Injector injector =
        Guice.createInjector(
            new AbstractModule() {
              @Override
              protected void configure() {
                bind(F.class).to(RealF.class);
                bind(G.class).to(RealG.class);
              }
            });
    F f = injector.getInstance(F.class);
    assertEquals("F", f.g().f().toString());
    assertEquals("G", f.g().f().g().toString());
  }

  public interface F {
    G g();
  }

  @Singleton
  public static class RealF implements F {
    private final G g;

    @Inject
    RealF(G g) {
      this.g = g;
    }

    @Override
    public G g() {
      return g;
    }

    @Override
    public String toString() {
      return "F";
    }
  }

  public interface G {
    F f();
  }

  @Singleton
  public static class RealG implements G {
    private final F f;

    @Inject
    RealG(F f) {
      this.f = f;
    }

    @Override
    public F f() {
      return f;
    }

    @Override
    public String toString() {
      return "G";
    }
  }

  /**
   * Tests that ProviderInternalFactory can detect circular dependencies before it gets to
   * Scopes.SINGLETON. This is especially important because the failure in Scopes.SINGLETON doesn't
   * have enough context to provide a decent error message.
   */
  public void testCircularDependenciesDetectedEarlyWhenDependenciesHaveDifferentTypes() {
    Injector injector =
        Guice.createInjector(
            new AbstractModule() {
              @Override
              protected void configure() {
                bind(Number.class).to(Integer.class);
              }

              @Provides
              @Singleton
              Integer provideInteger(List<Object> list) {
                return 2;
              }

              @Provides
              List<Object> provideList(Integer integer) {
                return new ArrayList<>();
              }
            });
    try {
      injector.getInstance(Number.class);
      fail();
    } catch (ProvisionException expected) {
      assertContains(
          expected.getMessage(),
          "Tried proxying Integer to support a circular dependency, ",
          "but it is not an interface.");
    }
  }

  public void testPrivateModulesDontTriggerCircularErrorsInProviders() {
    Injector injector =
        Guice.createInjector(
            new AbstractModule() {
              @Override
              protected void configure() {
                install(
                    new PrivateModule() {
                      @Override
                      protected void configure() {
                        bind(Foo.class);
                        expose(Foo.class);
                      }

                      @Provides
                      String provideString(Bar bar) {
                        return new String("private 1, " + bar.string);
                      }
                    });
                install(
                    new PrivateModule() {
                      @Override
                      protected void configure() {
                        bind(Bar.class);
                        expose(Bar.class);
                      }

                      @Provides
                      String provideString() {
                        return new String("private 2");
                      }
                    });
              }
            });
    Foo foo = injector.getInstance(Foo.class);
    assertEquals("private 1, private 2", foo.string);
  }

  static class Foo {
    @Inject String string;
  }

  static class Bar {
    @Inject String string;
  }

  /**
   * When Scope Providers call their unscoped Provider's get() methods are called, it's possible
   * that the result is a circular proxy designed for one specific parameter (not for all possible
   * parameters). But custom scopes typically cache the results without checking to see if the
   * result is a proxy. This leads to caching a result that is unsuitable for reuse for other
   * parameters.
   *
   * <p>This means that custom proxies have to do an {@code if(Scopes.isCircularProxy(..))} in order
   * to avoid exceptions.
   */
  public void testCustomScopeCircularProxies() {
    Injector injector =
        Guice.createInjector(
            new AbstractModule() {
              @Override
              protected void configure() {
                bindScope(SimpleSingleton.class, new BasicSingleton());
                bind(H.class).to(HImpl.class);
                bind(I.class).to(IImpl.class);
                bind(J.class).to(JImpl.class);
              }
            });

    // The reason this happens is because the Scope gets these requests, in order:
    // entry: Key<IImpl> (1 - from getInstance call)
    // entry: Key<HImpl>
    // entry: Key<IImpl> (2 - circular dependency from HImpl)
    // result of 2nd Key<IImpl> - a com.google.inject.$Proxy, because it's a circular proxy
    // result of Key<HImpl> - an HImpl
    // entry: Key<JImpl>
    // entry: Key<IImpl> (3 - another circular dependency, this time from JImpl)
    // At this point, if the first Key<Impl> result was cached, our cache would have
    //  Key<IImpl> caching to an instanceof of I, but not an an instanceof of IImpl.
    // If returned this, it would result in a ClassCastException or IllegalArgumentException
    // when filling in parameters for the constructor, because JImpl wants an IImpl, not an I.

    try {
      injector.getInstance(IImpl.class);
      fail();
    } catch (ProvisionException pe) {
      assertContains(
          pe.getMessage(),
          "Tried proxying CircularDependencyTest$IImpl"
              + " to support a circular dependency, but it is not an interface.",
          "1 error");
    }
  }

  interface H {}

  interface I {}

  interface J {}

  @SimpleSingleton
  static class HImpl implements H {
    @Inject
    HImpl(I i) {}
  }

  @SimpleSingleton
  static class IImpl implements I {
    @Inject
    IImpl(HImpl i, J j) {}
  }

  @SimpleSingleton
  static class JImpl implements J {
    @Inject
    JImpl(IImpl i) {}
  }

  @Target({ElementType.TYPE, ElementType.METHOD})
  @Retention(RUNTIME)
  @ScopeAnnotation
  public @interface SimpleSingleton {}

  public static class BasicSingleton implements Scope {
    private static Map<Key<?>, Object> cache = Maps.newHashMap();

    @Override
    public <T> Provider<T> scope(final Key<T> key, final Provider<T> unscoped) {
      return new Provider<T>() {
        @Override
        @SuppressWarnings("unchecked")
        public T get() {
          if (!cache.containsKey(key)) {
            T t = unscoped.get();
            if (Scopes.isCircularProxy(t)) {
              return t;
            }
            cache.put(key, t);
          }
          return (T) cache.get(key);
        }
      };
    }
  }

  public void testDisabledNonConstructorCircularDependencies() {
    Injector injector =
        Guice.createInjector(
            new AbstractModule() {
              @Override
              protected void configure() {
                binder().disableCircularProxies();
              }
            });

    try {
      injector.getInstance(K.class);
      fail("expected exception");
    } catch (ProvisionException expected) {
      assertContains(
          expected.getMessage(),
          "Found a circular dependency involving CircularDependencyTest$K"
              + ", and circular dependencies are disabled.");
    }

    try {
      injector.getInstance(L.class);
      fail("expected exception");
    } catch (ProvisionException expected) {
      assertContains(
          expected.getMessage(),
          "Found a circular dependency involving CircularDependencyTest$L"
              + ", and circular dependencies are disabled.");
    }
  }

  static class K {
    @Inject L l;
  }

  static class L {
    @Inject
    void inject(K k) {}
  }
}