Java example source code file (SpiBindingsTest.java)

This example Java source code file (SpiBindingsTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractmodule, binding, failingbindingscopingvisitor, failingelementvisitor, failingspitargetvisitor, failingtargetvisitor, injector, key, log, logging, override, providerbinding, providerinstancebinding, reflection, string, util, void

The SpiBindingsTest.java Java example source code

/**
 * Copyright (C) 2008 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.spi;

import static com.google.inject.Asserts.assertContains;
import static com.google.inject.Asserts.getDeclaringSourcePart;
import static com.google.inject.Asserts.isIncludeStackTraceComplete;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.inject.AbstractModule;
import com.google.inject.Binding;
import com.google.inject.Guice;
import com.google.inject.Inject;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.Module;
import com.google.inject.Provider;
import com.google.inject.Scope;
import com.google.inject.Scopes;
import com.google.inject.Singleton;
import com.google.inject.Stage;
import com.google.inject.name.Names;

import junit.framework.AssertionFailedError;
import junit.framework.TestCase;

import java.lang.reflect.Constructor;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.logging.Logger;

/**
 * @author jessewilson@google.com (Jesse Wilson)
 */
public class SpiBindingsTest extends TestCase {

  public void testBindConstant() {
    checkInjector(
        new AbstractModule() {
          protected void configure() {
            bindConstant().annotatedWith(Names.named("one")).to(1);
          }
        },

        new FailingElementVisitor() {
          @Override public <T> Void visit(Binding binding) {
            assertTrue(binding instanceof InstanceBinding);
            assertEquals(Key.get(Integer.class, Names.named("one")), binding.getKey());
            return null;
          }
        }
    );
  }

  public void testToInstanceBinding() {
    checkInjector(
        new AbstractModule() {
          protected void configure() {
            bind(String.class).toInstance("A");
          }
        },

        new FailingElementVisitor() {
          @Override public <T> Void visit(Binding binding) {
            assertTrue(binding instanceof InstanceBinding);
            checkBindingSource(binding);
            assertEquals(Key.get(String.class), binding.getKey());
            binding.acceptTargetVisitor(new FailingTargetVisitor<T>() {
              @Override public Void visit(InstanceBinding<? extends T> binding) {
                assertEquals("A", binding.getInstance());
                return null;
              }
            });
            binding.acceptScopingVisitor(new FailingBindingScopingVisitor() {
              public Void visitEagerSingleton() {
                return null;
              }
            });
            return null;
          }
        }
    );
  }

  public void testToProviderBinding() {
    final Provider<String> stringProvider = new StringProvider();

    checkInjector(
        new AbstractModule() {
          protected void configure() {
            bind(String.class).toProvider(stringProvider);
          }
        },

        new FailingElementVisitor() {
          @Override public <T> Void visit(Binding binding) {
            assertTrue(binding instanceof ProviderInstanceBinding);
            checkBindingSource(binding);
            assertEquals(Key.get(String.class), binding.getKey());
            binding.acceptTargetVisitor(new FailingTargetVisitor<T>() {
              @Override public Void visit(
                  ProviderInstanceBinding<? extends T> binding) {
                assertSame(stringProvider, binding.getUserSuppliedProvider());
                return null;
              }
            });
            return null;
          }
        }
    );
  }

  public void testToProviderKeyBinding() {
    checkInjector(
        new AbstractModule() {
          protected void configure() {
            bind(String.class).toProvider(StringProvider.class);
          }
        },

        new FailingElementVisitor() {
          @Override public <T> Void visit(Binding binding) {
            assertTrue(binding instanceof ProviderKeyBinding);
            checkBindingSource(binding);
            assertEquals(Key.get(String.class), binding.getKey());
            binding.acceptTargetVisitor(new FailingTargetVisitor<T>() {
              @Override public Void visit(ProviderKeyBinding<? extends T> binding) {
                assertEquals(Key.get(StringProvider.class), binding.getProviderKey());
                return null;
              }
            });
            return null;
          }
        }
    );
  }

  public void testToKeyBinding() {
    final Key<String> aKey = Key.get(String.class, Names.named("a"));
    final Key<String> bKey = Key.get(String.class, Names.named("b"));

    checkInjector(
        new AbstractModule() {
          protected void configure() {
            bind(aKey).to(bKey);
            bind(bKey).toInstance("B");
          }
        },

        new FailingElementVisitor() {
          @Override public <T> Void visit(Binding binding) {
            assertTrue(binding instanceof LinkedKeyBinding);
            checkBindingSource(binding);
            assertEquals(aKey, binding.getKey());
            binding.acceptTargetVisitor(new FailingTargetVisitor<T>() {
              @Override public Void visit(LinkedKeyBinding<? extends T> binding) {
                assertEquals(bKey, binding.getLinkedKey());
                return null;
              }
            });
            return null;
          }
        },

        new FailingElementVisitor() {
          @Override public <T> Void visit(Binding binding) {
            assertEquals(bKey, binding.getKey());
            return null;
          }
        }
    );
  }

  public void testToConstructorBinding() {
    checkInjector(
        new AbstractModule() {
          protected void configure() {
            bind(D.class);
          }
        },

        new FailingElementVisitor() {
          @Override public <T> Void visit(Binding binding) {
            assertTrue(binding instanceof ConstructorBinding);
            checkBindingSource(binding);
            assertEquals(Key.get(D.class), binding.getKey());
            binding.acceptTargetVisitor(new FailingTargetVisitor<T>() {
              @Override public Void visit(ConstructorBinding<? extends T> binding) {
                Constructor<?> expected = D.class.getDeclaredConstructors()[0];
                assertEquals(expected, binding.getConstructor().getMember());
                assertEquals(ImmutableSet.<InjectionPoint>of(), binding.getInjectableMembers());
                return null;
              }
            });
            return null;
          }
        }
    );
  }

  public void testConstantBinding() {
    checkInjector(
        new AbstractModule() {
          protected void configure() {
            bindConstant().annotatedWith(Names.named("one")).to(1);
          }
        },

        new FailingElementVisitor() {
          @Override public <T> Void visit(Binding binding) {
            assertTrue(binding instanceof InstanceBinding);
            checkBindingSource(binding);
            assertEquals(Key.get(Integer.class, Names.named("one")), binding.getKey());
            binding.acceptTargetVisitor(new FailingTargetVisitor<T>() {
              @Override public Void visit(InstanceBinding<? extends T> binding) {
                assertEquals(1, binding.getInstance());
                return null;
              }
            });
            return null;
          }
        }
    );
  }

  public void testConvertedConstantBinding() {
    Injector injector = Guice.createInjector(new AbstractModule() {
      protected void configure() {
        bindConstant().annotatedWith(Names.named("one")).to("1");
      }
    });

    Binding<Integer> binding = injector.getBinding(Key.get(Integer.class, Names.named("one")));
    assertEquals(Key.get(Integer.class, Names.named("one")), binding.getKey());
    checkBindingSource(binding);
    assertTrue(binding instanceof ConvertedConstantBinding);
    binding.acceptTargetVisitor(new FailingTargetVisitor<Integer>() {
      @Override public Void visit(
          ConvertedConstantBinding<? extends Integer> binding) {
        assertEquals((Integer) 1, binding.getValue());
        assertEquals(Key.get(String.class, Names.named("one")), binding.getSourceKey());
        return null;
      }
    });
  }

  public void testProviderBinding() {
    Injector injector = Guice.createInjector(new AbstractModule() {
      protected void configure() {
        bind(String.class).toInstance("A");
      }
    });

    Key<Provider providerOfStringKey = new Key>() {};
    Binding<Provider binding = injector.getBinding(providerOfStringKey);
    assertEquals(providerOfStringKey, binding.getKey());
    checkBindingSource(binding);
    assertTrue(binding instanceof ProviderBinding);
    binding.acceptTargetVisitor(new FailingTargetVisitor<Provider() {
      @Override public Void visit(
          ProviderBinding<? extends Provider binding) {
        assertEquals(Key.get(String.class), binding.getProvidedKey());
        return null;
      }
    });
  }

  public void testScopes() {
    checkInjector(
        new AbstractModule() {
          protected void configure() {
            bind(String.class).annotatedWith(Names.named("a"))
                .toProvider(StringProvider.class).in(Singleton.class);
            bind(String.class).annotatedWith(Names.named("b"))
                .toProvider(StringProvider.class).in(Scopes.SINGLETON);
            bind(String.class).annotatedWith(Names.named("c"))
                .toProvider(StringProvider.class).asEagerSingleton();
            bind(String.class).annotatedWith(Names.named("d"))
                .toProvider(StringProvider.class);
          }
        },

        new FailingElementVisitor() {
          @Override public <T> Void visit(Binding command) {
            assertEquals(Key.get(String.class, Names.named("a")), command.getKey());
            command.acceptScopingVisitor(new FailingBindingScopingVisitor() {
              @Override public Void visitScope(Scope scope) {
                // even though we bound with an annotation, the injector always uses instances
                assertSame(Scopes.SINGLETON, scope);
                return null;
              }
            });
            return null;
          }
        },

        new FailingElementVisitor() {
          @Override public <T> Void visit(Binding command) {
            assertEquals(Key.get(String.class, Names.named("b")), command.getKey());
            command.acceptScopingVisitor(new FailingBindingScopingVisitor() {
              @Override public Void visitScope(Scope scope) {
                assertSame(Scopes.SINGLETON, scope);
                return null;
              }
            });
            return null;
          }
        },

        new FailingElementVisitor() {
          @Override public <T> Void visit(Binding command) {
            assertEquals(Key.get(String.class, Names.named("c")), command.getKey());
            command.acceptScopingVisitor(new FailingBindingScopingVisitor() {
              @Override public Void visitEagerSingleton() {
                return null;
              }
            });
            return null;
          }
        },

        new FailingElementVisitor() {
          @Override public <T> Void visit(Binding command) {
            assertEquals(Key.get(String.class, Names.named("d")), command.getKey());
            command.acceptScopingVisitor(new FailingBindingScopingVisitor() {
              @Override public Void visitNoScoping() {
                return null;
              }
            });
            return null;
          }
        }
    );
  }
  
  public void testExtensionSpi() {
    final AtomicBoolean visiting = new AtomicBoolean(false);
    
    final Injector injector = Guice.createInjector(new AbstractModule() {
      protected void configure() {
        bind(String.class).toProvider(new ProviderWithExtensionVisitor<String>() {
          public <B, V> V acceptExtensionVisitor(BindingTargetVisitor visitor,
              ProviderInstanceBinding<? extends B> binding) {
            assertSame(this, binding.getUserSuppliedProvider());
            // We can't always check for FailingSpiTargetVisitor,
            // because constructing the injector visits here, and we need
            // to process the binding as normal
            if(visiting.get()) {
              assertTrue("visitor: " + visitor, visitor instanceof FailingSpiTargetVisitor);
              return (V)"visited";
            } else {
              return visitor.visit(binding);
            }
          }
          
          public String get() {
            return "FooBar";
          }
        });
      }
    });
    
    visiting.set(true);

    // Check for Provider<String> binding -- that is still a ProviderBinding.
    Key<Provider providerOfStringKey = new Key>() {};
    Binding<Provider providerBinding = injector.getBinding(providerOfStringKey);
    assertEquals(providerOfStringKey, providerBinding.getKey());
    checkBindingSource(providerBinding);
    assertTrue("binding: " + providerBinding, providerBinding instanceof ProviderBinding);
    providerBinding.acceptTargetVisitor(new FailingTargetVisitor<Provider() {
      @Override public Void visit(ProviderBinding<? extends Provider binding) {
        assertEquals(Key.get(String.class), binding.getProvidedKey());
        return null;
      }
    });
    
    // Check for String binding -- that one is ProviderInstanceBinding, and gets hooked
    Binding<String> binding = injector.getBinding(String.class);
    assertEquals(Key.get(String.class), binding.getKey());
    checkBindingSource(binding);
    assertTrue(binding instanceof ProviderInstanceBinding);
    assertEquals("visited", binding.acceptTargetVisitor(new FailingSpiTargetVisitor<String>()));
  }

  private static class FailingSpiTargetVisitor<T> extends DefaultBindingTargetVisitor {
    @Override
    protected String visitOther(Binding<? extends T> binding) {
      throw new AssertionFailedError();
    }
  }

  public void checkBindingSource(Binding binding) {
    assertContains(binding.getSource().toString(), getDeclaringSourcePart(getClass()));
    ElementSource source = (ElementSource) binding.getSource();
    assertFalse(source.getModuleClassNames().isEmpty());
    if (isIncludeStackTraceComplete()) {
      assertTrue(source.getStackTrace().length > 0);
    } else {
      assertEquals(0, source.getStackTrace().length);
    }
  }
  
  public void checkInjector(Module module, ElementVisitor<?>... visitors) {
    Injector injector = Guice.createInjector(module);

    List<Binding bindings = Lists.newArrayList(injector.getBindings().values());
    for (Iterator<Binding i = bindings.iterator(); i.hasNext(); ) {
      if (BUILT_IN_BINDINGS.contains(i.next().getKey())) {
        i.remove();
      }
    }

    Collections.sort(bindings, orderByKey);

    assertEquals(bindings.size(), visitors.length);

    for (int i = 0; i < visitors.length; i++) {
      ElementVisitor<?> visitor = visitors[i];
      Binding<?> binding = bindings.get(i);
      binding.acceptVisitor(visitor);
    }
  }

  private final ImmutableSet<Key BUILT_IN_BINDINGS = ImmutableSet.of(
      Key.get(Injector.class), Key.get(Stage.class), Key.get(Logger.class));

  private final Comparator<Binding orderByKey = new Comparator>() {
    public int compare(Binding<?> a, Binding b) {
      return a.getKey().toString().compareTo(b.getKey().toString());
    }
  };

  private static class StringProvider implements Provider<String> {
    public String get() {
      return "A";
    }
  }

  private static class C { }

  private static class D extends C {
    @Inject public D(Injector unused) { }
  }
}