How do I test Guice injections?

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Answers

  1. Carmelo

    • 2016/2/7

    IMHO, you should not be testing that. The Google Guice guys have the unit tests to assert that the injections work as expected - after all, that's what Guice is designed to do. You should only be writing tests for your own code (A and B).

  2. Kylian

    • 2016/4/17

    I am new in google guice and got stuck in writing test for a guice project. have to have public constructor for Classes that use guice injection.

  3. Adrien

    • 2019/4/30

    Injecting JUnit tests with Guice using a Rule, Java unit tests, JUnit class runner,Guice injector and modules, dependency injection, design patterns. The Google Guice guys have the unit tests to assert that the injections work as expected - after all, that's what Guice is designed to do. You should only be writing tests for your own code (A and B).

  4. Serra

    • 2020/9/2

    Testing with Guice. If you're using Guice for dependency injection then you can directly configure how components and applications are created for tests. This 

  5. Julio

    • 2020/12/5

    Another way to test your configuration is by having a test suite that tests your app end-to-end. Although end-to-end tests nominally test use cases they indirectly check that your app is configured correctly, (that all the dependencies are wired, etc etc). Unit tests on the other hand should focus exclusively on the domain, and not on the context in which your code is deployed.

    I also agree with NamshubWriter's answer. I'm am not against tests that check configuration as long as they are grouped in a separate test suite to your unit tests.

  6. Fontana

    • 2021/3/9

    Google Guice is the framework to automate the dependency injection in applications. If you have come across directly here, I would recommend you to check out Dependency Injection Example where we learned the problems with traditional approach of Object creation and implementation benefits of dependency injection.

  7. Kash

    • 2019/4/27

    2. Setup. In order to use Google Guice in your Maven project, you will need to add the following dependency to your pom.xml: <dependency> 

  8. Thatcher

    • 2017/12/25

    By using Guice (or any DI) in unit tests you are hiding away a warning that your class is getting too big and taking on too many responsibilities. For testing the bootstrapper code and integration tests then yes create a different injector for each test. 

  9. Mariani

    • 2018/9/6

    I don't think you should test private members being set. Better to test against the public interface of your class. If member "b" wouldn't be injected, you'll probably get a NullPointerException executing your tests, which should be plenty of warning.

  10. Piras

    • 2017/7/13

    Guice Maven Dependency. Get link; Facebook; Twitter; Pinterest; Email; Other Apps. Guice is an open-source, Java-based dependency injection framework. It is 

  11. Emilio

    • 2020/4/8

    I am having hard time figuring out how to inject objects into my custom validator, that is running in Dropwizard? Do I need to do extra steps in order to get injections working in DW? Or what yoy have in README steps will work out of the

  12. Avery

    • 2016/2/21

    Guice still asks for dependencies from ModuleA during injector creation. But when I change the methods to Provider classes and bind them like 

  13. Gomez

    • 2018/8/28

    For any complex Guice project, you should add tests to make sure that the modules can be used to create your classes. In your example, if B were a type that Guice couldn't figure out how to create, then Guice won't be able to create A. If A wasn't needed to start the server but was needed when your server was handling a request, that would cause problems.

    In my projects, I write tests for non-trivial modules. For each module, I use requireBinding() to declare what bindings the module requires but doesn't define. In my tests, I create a Guice injector using the module under test and another module that provides the required bindings. Here's an example using JUnit4 and JMock:

    /** Module that provides LoginService */
    public class LoginServiceModule extends AbstractModule {
      @Override 
      protected void configure() {
        requireBinding(UserDao.class);
      }
    
      @Provides
      LoginService provideLoginService(UserDao dao) {
        ...
      }
    }
    
    @RunWith(JMock.class)
    public class LoginServiceModuleTest {
      private final Mockery context = new Mockery();
    
      @Test
      public void testModule() {
        Injector injector = Guice.createInjector(
            new LoginServiceModule(), new ModuleDeps());
    
        // next line will throw an exception if dependencies missing
        injector.getProvider(LoginService.class);
      }
    
      private class ModuleDeps extends AbstractModule {
        private final UserDao fakeUserDao;
    
        public ModuleDeps() {
          fakeUserDao = context.mock(UserDao.class);
        }
    
        @Override 
        protected void configure() {}
    
        @Provides
        Server provideUserDao() {
          return fakeUserDao;
        }
      }
    }
    

    Notice how the test only asks for a provider. That's sufficient to determine that Guice could resolve the bindings. If LoginService was created by a provider method, this test wouldn't test the code in the provider method.

    This test also doesn't test that you binded the right thing to UserDao, or that UserDao was scoped correctly. Some would argue that those types of things are rarely worth checking; if there's a problem, it happens once. You should "test until fear turns to boredom."

    I find Module tests useful because I often add new injection points, and it's easy to forget to add a binding.

    The requireBinding() calls can help Guice catch missing bindings before it returns your injector! In the above example, the test would still work if the requireBinding() calls were not there, but I like having them because they serve as documentation.

    For more complicated modules (like my root module) I might use Modules.override() to override bindings that I don't want at test time (for instance, if I want to verify that my root object to be created, I probably don't want it to create an object that will connect to the database). For simple projects, you might only test the top-level module.

    Note that Guice will not inject nulls unless the field as annotated with @Nullable so you very rarely need to verify that the injected objects are non-null in your tests. In fact, when I annotate constructors with @Inject I do not bother to check if the parameters are null (in fact, my tests often inject null into the constructor to keep the tests simple).

  14. Everett

    • 2020/7/14

    The author suggested to create a custom JUnit class runner that overrides the default behaviour and, in addition to instancing the test class, it configures Guice and injects the dependencies in the test class instance. The custom class runner must be passed to the JUnit @RunWith annotation. This is a more elegant solution with respect to the

  15. Jackson

    • 2020/2/27

    In Guice, the new keyword is replaced with @inject for injecting dependency. It allows constructors, fields, and methods (any method with 

  16. Cash

    • 2018/11/15

    Google Guice - Field Injection - Injection is a process of injecting dependeny into an object. Field injection is used to set value object as dependency to the field of an object.

  17. Waylon

    • 2016/8/27

    Injecting Field Dependencies. Instead of using constructor arguments, dependencies can be injected directly to a field. This is the most concise 

  18. Jaden

    • 2021/1/4

    Google Guice - Constructor Injection - Injection is a process of injecting dependeny into an object. Constructor injection is quite common. In this process, dependency is injected as argument to the

  19. D'Amico

    • 2020/2/6

    Google Guice - Core Library. com.google.inject:guice 4.1.0.

  20. Jaxton

    • 2018/9/5

    To answer this question first we need to discuss what makes beer fizzy and how a head forms.. Most beers are carbonated with carbon dioxide (CO 2).When the beer is in the can some of this CO 2 is dissolved in the beer and some is at the top of the can.

  21. Cristian

    • 2016/7/24

    Let me first show what field injection looks like: is an example from the PicoContainer website, but Spring and Google Guice can do this too.

  22. Angel

    • 2019/4/16

    java,junit,guice. My solution was to add a RatingId class that wraps an integer and create a factory RatingIds that I could then return static and use as parameters. I overloaded the getRatingById method in my RatingService interface to accept the new RatingId type, and then inject the rating service into my

  23. Cattaneo

    • 2017/11/28

    This annotation marks an injection point. Guice will attempt to reconcile the dependencies implied by the annotated constructor, method, or field. Constructor​- 

  24. Rhett

    • 2015/6/9

    Builds the graphs of objects that make up your application. The injector tracks the dependencies for each type and uses bindings to inject them. This is the core of Guice, although you rarely interact with it directly. This "behind-the-scenes" operation is what distinguishes dependency injection from its cousin, the service locator pattern.

  25. Carlos

    • 2018/4/11

    MavenRepository · Categories | Popular | Contact Us Home » com.google.​inject » guice. Google Guice Core Library. Google Guice Core Library 

  26. Foster

    • 2021/8/10

    It predates Guice by 5 years. It's a primarly XML oriented framework, but it does a lot more than Guice. It does some dependency injection, but also comes with a full MVC web framework. Guice, while being simpler (by virtue of being focused on a small task and having hindsight), also manages to accomplish more in less code. Because it's just

  27. Permeti

    • 2021/6/27

  28. Phillip

    • 2017/9/5

    We would like to show you a description here but the site won’t allow us.

  29. Bjorn

    • 2015/12/31

    Guice is a lightweight dependency injection framework for Java 6 and above. Last Release on Oct 28, 2020. 4. Google Inject Integration1 usages.

  30. Giuliani

    • 2019/3/30

    GUICE is a light, compact powder packed in pocket-size sachets and big tubs. Easy to carry around, easy to store, easy to stock up on and easy to prepare. Sooo yeah. Easy.

  31. Fabbri

    • 2021/2/28

    I have no idea what a Jolira version is. The latest official release version of Guice is 2.0. However, version 3.0 is (hopefully) coming sometime in the near future.

  32. Travis

    • 2017/12/5

    So if you want to use Guice to inject MyRepository (with any type) implementation whenever you need a new instance of Repository (with any type) then you don't have to think about generics at all, but you're on your own to ensure type safety (that's why you get those pesky "unchecked" warning).

  33. Conor

    • 2021/7/14

    Guice supports the standard types of injections you would have come to expect with the DI pattern. In the Communicator class, we need to inject 

  34. Marlon

    • 2017/12/25

    Google Guice is the framework to automate the dependency injection in applications. If you have come across directly here, I would recommend you to check out Dependency Injection Example where we learned the problems with traditional approach of Object creation and implementation benefits of dependency injection.

  35. Ray

    • 2019/2/16

    You should really avoid using Guice in unit tests as each test should be JUnit5 is still new to me, so I may be looking into templates, but so far 

  36. Malik

    • 2020/3/11

    Class Overview. A support class for Modules which reduces repetition and results in a more readable configuration. Simply extend this class, implement configure(), and call the inherited methods which mirror those found in Binder.

  37. Elijah

    • 2017/9/7

    This might not be the answer you're looking for, but if you're writing unit tests, you probably shouldn't be using an injector and rather be 

  38. Alexzander

    • 2018/11/19

    In my projects, I write tests for non-trivial modules. For each module, I use requireBinding() to declare what bindings the module requires but doesn't define. In my tests, I create a Guice injector using the module under test and another module that provides the required bindings. Here's an example using JUnit4 and JMock:

  39. Gentile

    • 2020/7/21

    Update workflow to cache maven packages. 6 hours ago .github/workflows · bom · Bump snapshot version, update README & prior API xml. 3 months ago. bom.

  40. Luciano

    • 2015/12/12

    If you’re unit testing components with JUnit you surely face where to put the initialization code that reads the Guice configuration modules and creates the injector(s). As a trivial solution you could make every test class to extend a common class with a static method that is annotated with @BeforeClass ; this method has to be used once per

  41. Emmanuel

    • 2019/9/2

    Java example source code file: BoundFieldModule.java (bind, boundfieldinfo, class, field, object, typeliteral)

  42. Theo

    • 2017/2/3

    Contribute to codingwell/scala-guice development by creating an account on GitHub. (" A ") // To override the default binding (likely in another module

  43. William

    • 2015/12/18

    dev.to › tbutterwith › dependency-injection-in-java-with-guice-51pk

  44. Bruno

    • 2016/2/4

    Guice is a dependency injection (DI) framework. I've suggested for years that developers use DI, because it improves maintainability, testability, and flexibility. By watching engineers react to Guice, I've learned that the best way to convince a programmer to adopt a new technology is to make it really eas

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