Package com.google.inject.testing.fieldbinder

Class BoundFieldModule

java.lang.Object

com.google.inject.testing.fieldbinder.BoundFieldModule

All Implemented Interfaces:

Module

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);
   }
 }
 

See Also:

Bind

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	BoundFieldModule.BoundFieldInfo	Information about a field bound by BoundFieldModule.
static class	BoundFieldModule.WithPermits	Wrapper of BoundFieldModule which enables attaching @RestrictedBindingSource permits to instances of it.

Method Summary

Modifier and Type	Method	Description
void	configure(Binder binder)	Contributes bindings and other configurations for this module to binder.
ImmutableSet<BoundFieldModule.BoundFieldInfo>	getBoundFields()	Returns information about the fields bound by this module.
Object	getInstance()	Returns the object originally passed to of(java.lang.Object)).
static BoundFieldModule	of(Object instance)	Create a BoundFieldModule which binds the Bind annotated fields of instance.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

of

@CheckReturnValue
public static BoundFieldModule of(Object instance)

Create a BoundFieldModule which binds the Bind annotated fields of instance.

Parameters:

instance - the instance whose fields will be bound.

Returns:

a module which will bind the Bind annotated fields of instance.

getInstance

public Object getInstance()

Returns the object originally passed to of(java.lang.Object)).

getBoundFields

public ImmutableSet<BoundFieldModule.BoundFieldInfo> getBoundFields()

Returns information about the fields bound by this module.

Note this is available immediately after construction, fields with errors won't be included but their error messages will be deferred to configuration time.

Fields with invalid null values are included but still cause errors at configuration time.

configure

public void configure(Binder binder)

Description copied from interface: Module

Contributes bindings and other configurations for this module to binder.

Do not invoke this method directly to install submodules. Instead use Binder.install(Module), which ensures that provider methods are discovered.

Specified by:

configure in interface Module