public final class BoundFieldModule
extends Object
implements Module

A Guice module that automatically adds Guice bindings into the injector for all Bind annotated fields of a specified object.

This module is intended for use in tests to reduce the amount of boilerplate code needed to bind local fields (usually mocks) for injection.

The following rules are followed in determining how fields are bound using this module:

• For each Bind annotated field of an object and its superclasses, this module will bind that field's type to that field's value at injector creation time. This includes both instance and static fields.
• If Bind.to() is specified, the field's value will be bound to the class specified by Bind.to() instead of the field's actual type.
• If Bind.lazy() is true, this module will delay reading the value from the field until injection time, allowing the field's value to be reassigned during the course of a test's execution.
• If a BindingAnnotation or Qualifier is present on the field, that field will be bound using that annotation via AnnotatedBindingBuilder.annotatedWith(java.lang.Class<? extends java.lang.annotation.Annotation>). For example, bind(Foo.class).annotatedWith(BarAnnotation.class).toInstance(theValue). It is an error to supply more than one BindingAnnotation or Qualifier.
• If the field is of type Provider, the field's value will be bound as a Provider using LinkedBindingBuilder.toProvider(com.google.inject.Provider<? extends T>) to the provider's parameterized type. For example, Provider<Integer> binds to Integer. Attempting to bind a non-parameterized Provider without a Bind.to() clause is an error.

Example use:

 public class TestFoo {
   // bind(new TypeLiteral<List<Object>>() {}).toInstance(listOfObjects);
   {@literal @}Bind private List<Object> listOfObjects = Lists.of();

   // private String userName = "string_that_changes_over_time";
   // bind(String.class).toProvider(new Provider() { public String get() { return userName; }});
   {@literal @}Bind(lazy = true) private String userName;

   // bind(SuperClass.class).toInstance(aSubClass);
   {@literal @}Bind(to = SuperClass.class) private SubClass aSubClass = new SubClass();

   // bind(String.class).annotatedWith(MyBindingAnnotation.class).toInstance(myString);
   {@literal @}Bind
   {@literal @}MyBindingAnnotation
   private String myString = "hello";

   // bind(Object.class).toProvider(myProvider);
   {@literal @}Bind private Provider<Object> myProvider = getProvider();

   {@literal @}Before public void setUp() {
     Guice.createInjector(BoundFieldModule.of(this)).injectMembers(this);
   }
 }