{#========================================== Docs : "Testing" ==========================================#}

Testing

Spincast provides some nice testing utilities. You obviously don't have to use those to test your Spincast application, you may already have your favorite testing toolbox and be happy with it. But those utilities are heavily used to test Spincast itself, and we think they are an easy, fun, and very solid testing foundation.

First, Spincast comes with a custom JUnit runner which allows testing using a Guice context really easily. But, the biggest feature is to be able to test your real application itself, without even changing the way it is bootstrapped. This is possible because of the Guice Tweaker component which allows to indirectly mock or extend some components.

{#========================================== Installation ==========================================#}

Installation

Add this Maven artifact to your project to get access to the Spincast testing utilities: 

<dependency>
    <groupId>org.spincast</groupId>
    <artifactId>spincast-testing-default</artifactId>
    <version>{{spincast.spincastCurrrentVersion}}</version>
    <scope>test</scope>
</dependency>

Then, make your test classes extend SpincastTestBase or one of its children classes.

Most of the time, you'll want to extend AppBasedTestingBase, or AppBasedDefaultContextTypesTestingBase if your application uses the default request context types.

{#========================================== Testing demo ==========================================#}

Demo

In this demo, we're going to test a simple application which only has one endpoint : "/sum". The Route Handler associated with this endpoint is going to receive two numbers, will add them up, and will return the result as a Json object. Here's the response we would be expecting from the "/sum" endpoint when sending the parameters "first" = "1" and "second" = "2" : 

{
  "result": "3"
}

You can download that Sum application [.zip] if you want to try it by yourself or look at its code directly.

First, let's have a quick look at how the demo application is bootstrapped : 

public class App {

    public static void main(String[] args) {
        Spincast.configure()
                .module(new AppModule())
                .init(args);
    }

    @Inject
    protected void init(DefaultRouter router,
                        AppController ctrl,
                        Server server) {

        router.POST("/sum").handle(ctrl::sumRoute);
        server.start();
    }
}

The interesting lines to note here are 4-6 : we use the standard Bootstrapper to start everything! We'll see that, without modifying this bootstrapping process, we'll still be able to tweak the Guice context, to mock some components.

Let's write a first test class : 


public class SumTest extends AppBasedDefaultContextTypesTestingBase {

    @Override
    protected void callAppMainMethod() {
        App.main(null);
    }
    
    @Override
    protected AppTestingConfigs getAppTestingConfigs() {
        return new AppTestingConfigs() {

            @Override
            public boolean isBindAppClass() {
                return true;
            }

            @Override
            public Class<? extends SpincastConfig> getSpincastConfigTestingImplementationClass() {
                return SpincastConfigTestingDefault.class;
            }

            @Override
            public Class<?> getAppConfigTestingImplementationClass() {
                return null;
            }

            @Override
            public Class<?> getAppConfigInterface() {
                return null;
            }
        };
    }

    @Inject
    private JsonManager jsonManager;

    @Test
    public void validRequest() throws Exception {
        // TODO...
    }
}

Explanation :

As you can see, simply by extending AppBasedDefaultContextTypesTestingBase, and by starting our application using its main(...) method, we can write integration tests targeting our running application, and we can use any components from its Guice context. There is some boilerplate code to write though (you nee to implement the getAppTestingConfigs() method, for example), and this why you would in general create a base class to serve as a parent for all your test classes!

Let's implement our first test. We're going to validate that the "/sum" endpoint of the application works properly : 

   //...

    @Test
    public void validRequest() throws Exception {
    
        HttpResponse response = POST("/sum").addFormBodyFieldValue("first", "1")
                                            .addFormBodyFieldValue("second", "2")
                                            .addJsonAcceptHeader()
                                            .send();
    
        assertEquals(HttpStatus.SC_OK, response.getStatus());
        assertEquals(ContentTypeDefaults.JSON.getMainVariationWithUtf8Charset(),
                     response.getContentType());
    
        String content = response.getContentAsString();
        assertNotNull(content);
    
        JsonObject resultObj = this.jsonManager.fromString(content);
        assertNotNull(resultObj);
    
        assertEquals(new Integer(3), resultObj.getInteger("result"));
        assertNull(resultObj.getString("error", null));
    }

Explanation :

Note that we could also have retrieved the content of the response as a JsonObject directly, by using response.getContentAsJsonObject() instead of response.getContentAsString(). But we wanted to demonstrate the use of an injected component, so bear with us!

If you look at the source of this demo, you'll see two more tests in that first test class : one that tests the endpoint when a parameter is missing, and one that tests the endpoint when the sum overflows the maximum Integer value.

Let's now write a second test class. In this one, we are going to show how easy it is to replace a binding, to mock a component.

Let's say we simply want to test that the responses returned by our application are gzipped. We may not care about the actual result of calling the "/sum" endpoint, so we are going to "mock" it. This is a simple example, but the process involved is similar if you need to mock a data source, for example.

Our second test class will look like this : 


public class ResponseIsGzippedTest extends AppBasedDefaultContextTypesTestingBase {

    @Override
    protected void callAppMainMethod() {
        App.main(null);
    }
    
    @Override
    protected AppTestingConfigs getAppTestingConfigs() {
        return new AppTestingConfigs() {

            @Override
            public boolean isBindAppClass() {
                return true;
            }

            @Override
            public Class<? extends SpincastConfig> getSpincastConfigTestingImplementationClass() {
                return SpincastConfigTestingDefault.class;
            }

            @Override
            public Class<?> getAppConfigTestingImplementationClass() {
                return null;
            }

            @Override
            public Class<?> getAppConfigInterface() {
                return null;
            }
        };
    }

    public static class AppControllerTesting extends AppControllerDefault {

        @Override
        public void sumRoute(DefaultRequestContext context) {
            context.response().sendPlainText("42");
        }
    }

    @Override
    protected Module getExtraOverridingModule() {
        return new SpincastGuiceModuleBase() {

            @Override
            protected void configure() {
                bind(AppController.class).to(AppControllerTesting.class).in(Scopes.SINGLETON);
            }
        };
    }

    @Test
    public void isGzipped() throws Exception {
        // TODO...
    }
}

Explanation :

And let's write the test itself : 

    //...

    @Test
    public void isGzipped() throws Exception {
     
        HttpResponse response = POST("/sum").addFormBodyFieldValue("toto", "titi")
                                            .addJsonAcceptHeader()
                                            .send();
    
        assertTrue(response.isGzipped());
    
        assertEquals(HttpStatus.SC_OK, response.getStatus());
        assertEquals(ContentTypeDefaults.TEXT.getMainVariationWithUtf8Charset(),
                     response.getContentType());
        assertEquals("42", response.getContentAsString());  
    }

Explanation :

Being able to change bindings like this is very powerful : you are testing your real application, as it is bootstrapped, without even changing its code. All is done indirectly, using the Guice Tweaker.

{#========================================== Guice Tweaker ==========================================#}

Guice Tweaker

As we saw in the previous demo, we can tweak the Guice context of our application in order to test it. This is done by the GuiceTweaker, a component which is part of the Spincast testing machanism.

The Guice Tweaker is in fact a plugin. This plugin is special because it is applied even if it's not registered during the bootstrapping of the application.

It's important to know that the Guice Tweaker only works if you are using the standard Bootstrapper. It is implemented using a ThreadLocal that the bootstrapper will look for.

The Guice Tweaker is created in the SpincastTestBase class. By extending this class or one of its children, you have access to it.

By default, the Guice Tweaker automatically modifies the SpincastConfig binding of the application when tests are run. This allows you to use testing configurations very easily (for example to make sure the server starts on a free port). The implementation class used for those configurations are specified in the getAppTestingConfigs() method you have to implement. The Guice tweaker will use those informations and will create the required binding automatically. The default implementation for the SpincastConfig interface is SpincastConfigTestingDefault.

Those are the methods available, in a test file, to tweak your application :

{#========================================== Testing configurations ==========================================#}

The testing configurations (getAppTestingConfigs())

When running integration tests, you don't want to use the same configurations then the ones you would when running the application directly. For example, you may want to provide a different connection string to use a mocked database instead of the real one.

As we saw in the previous section, the Guice Tweaker allows you to change some bindings when testing your application. But configurations is such an important component to modify, when running tests, that Spincast forces you to specify which implementations to use for those!

You specify the testing configurations by implementing the getAppTestingConfigs() method. This method must return an instance of AppTestingConfigs. This object tells Spincast :

Spincast will use the informations returned by this object and will add all the required bindings automatically. You don't need to do anything by yourself, for example by using the Guice Tweaker, to change the bindings for the configurations when running integration tests. You just need to implement the getAppTestingConfigs() method.

In most applications, the testing implementation to use for the SpincastConfig interface and the one for your custom configurations interface will be the same! Indeed, if you follow the suggested way of configuring your application, then your custom configurations interface AppConfig extends SpincastConfig.

Your testing configurations can often be shared between multiple tests classes. It is therefore a good idea to create an abstract base class, named "AppTestingsBase" or something similar, to implement the getAppTestingConfigs() method there, and use this base class as the parent for all your integration test classes. Have a look at this base class for an example.

While mocking some configurations is often required, it's still a good idea to make testing configurations as close as possible as the ones that are going to be used in production. For example, returning false for the isDebugEnabled() method is suggested. That way, you can be confident that once your tests pass, your application will do well in production.

You can mock some Environment Variables used as configurations, by overriding the getEnvironmentVariables() method in your configurations implementation class.

{#========================================== Testing base classes ==========================================#}

Testing base classes

Multiple base classes are provided, depending on the needs of your test class. They all ultimately extend SpincastTestBase, they all use the Spincast JUnit runner and all give access to Guice Tweaker.

Those test base classes are split into two main categories : those based on your actual application and those that are not. Most of the time, you do want to test using the Guice context of your application! But you may sometimes have components that can be unit tested without the full Guice context of your application.

Those are the main testing base classes provided by Spincast. All of them can be modify using the Guice Tweaker :

App based

Not based on an app

{#========================================== Spincast JUnit runner ==========================================#}

Spincast JUnit runner

Spincast's testing base classes all use a custom JUnit runner: SpincastJUnitRunner.

This custom runner has a couple of differences as compared with the default JUnit runner, but the most important one is that instead of creating a new instance of the test class before each test, this runner only creates one instance.

This way of running the tests works very well when a Guice context is involved. The Guice context is created when the test class is initialized, and then this context is used to run all the tests of the class. If Integration testing is used, then the HTTP Server is started when the test class is initialized and it is used to run all the tests of the class.

Let's see in more details how the Spincast JUnit runner works :

Since the Guice context is shared by all the tests of a test class, you have to make sure you reset everything required before running a test. To do this, use JUnit's @Before annotation, or the beforeTest() and afterTest() method.

Spincast JUnit runner features

A quick note about the @Repeat annotation : this annotation should probably only be used for debugging purpose! A test should always be reproducible and should probably not have to be run multiple times. But this annotation, in association with the testFailure(...) method, can be a great help to debug a test which sometimes fails and you don't know why!

{#========================================== Managing cookies ==========================================#}

Managing cookies

A frequent need during integration testing is to be able to keep cookies across multiple requests... By doing so, the behavior of a real browser is simulated.

To keep the cookies sent by a response, simple call saveResponseCookies(response) when a valid response is received. Then, you can add back those cookies to a new request using .setCookies(getPreviousResponseCookies()): 

// First request, we save the cookies from the response...
HttpResponse response = GET("/one").send();
assertEquals(HttpStatus.SC_OK, response.getStatus());
saveResponseCookies(response);

// Second request, we resend the cookies!
response = GET("/two").setCookies(getPreviousResponseCookies()).send();
assertEquals(HttpStatus.SC_OK, response.getStatus());
saveResponseCookies(response);