martes, junio 27, 2017

Lifecycle of JUnit 5 Extension Model

JUnit5 final release is around the corner (currently it is M4), and I have started playing with it a bit on how to write extensions.

In JUnit5, instead of dealing with Runners, Rules, ClassRules and so on, you've got a single Extension API to implement your own extensions.

JUnit5 provides several interfaces to hook in its lifecycle. For example you can hook to Test Instance Post-processing to invoke custom initialization methods on the test instance, or Parameter Resolution for dynamically resolving test method parameters at runtime. And of course the typical ones like hooking before all tests are executed, before a test is executed, after a test is executed and so on so far, a complete list can be found at

But in which point of the process it is executed each of them? To test it I have just created an extension that implements all interfaces and each method prints who is it.

Then I have created a JUnit5 Test suite containing two tests:

So after executing this suite, what it is the output? Let's see it. Notice that for sake of readability I have added some callouts on terminal output.

<1> First test that it is run is AnotherLoggerExtensionTest. In this case there is only one simple test, so the lifecycle of extension is BeforeAll, Test Instance-Post-Processing, Before Each, Before Test Execution, then the test itself is executed, and then all After callbacks.

<2> Then the LoggerExtensionTest is executed. First test is not a parametrized test, so events related to parameter resolution are not called. Before the test method is executed, test instance post-processing is called, and after that all before events are thrown. Finally the test is executed with all after events.

<3> Second test contains requires a parameter resolution. Parameter resolvers are run after Before events and before executing the test itself.

<4> Last test throws an exception. Test Execution Exception is called after test is executed but before After events.

Last thing to notice is that BeforeAll and AfterAll events are executed per test class and not suite.

The JUnit version used in this example is org.junit.jupiter:junit-jupiter-api:5.0.0-M4

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viernes, junio 23, 2017

Test AWS cloud stack offline with Arquillian and LocalStack

When you are building your applications on AWS cloud stack (such as DynamoDB, S3, ...), you need to write tests against these components. The first idea you might have is to have one environment for production and another one for testing, and run tests against it.

This is fine for integration tests, deployment tests, end to end tests or performance tests, but for component tests it will be faster if you could run AWS cloud stack locally and offline.

Localstack provides this feature. It  provides a fully functional local AWS cloud stack so you can develop and test your cloud applications offline.

Localstack comes with different ways to start all stack, but the easiest one is by using Docker image. So if you run atlassianlabs/localstack then you get the stack up and running with next configuration:
  • API Gateway at http://localhost:4567
  • Kinesis at http://localhost:4568
  • DynamoDB at http://localhost:4569
  • DynamoDB Streams at http://localhost:4570
  • Elasticsearch at http://localhost:4571
  • S3 at http://localhost:4572
  • Firehose at http://localhost:4573
  • Lambda at http://localhost:4574
  • SNS at http://localhost:4575
  • SQS at http://localhost:4576
  • Redshift at http://localhost:4577
  • ES (Elasticsearch Service) at http://localhost:4578
  • SES at http://localhost:4579
  • Route53 at http://localhost:4580
  • CloudFormation at http://localhost:4581
  • CloudWatch at http://localhost:4582
So the next question is how do you automate all the process of starting the container, run the tests and finally stop everything and make it portable, so you don't need to worry if you are using Docker in Linux or MacOS? The answer is using Arquillian Cube.

Arquillian Cube is an Arquillian extension that can be used to manager Docker containers in your tests. To use it you need a Docker daemon running on a computer (it can be local or not), but probably it will be at local.

Arquillian Cube offers three different ways to define container(s):
  • Defining a docker-compose file.
  • Defining a Container Object.
  • Using Container Object DSL.
In this example I am going to show you Container Object DSL approach, but any of the others works as well.

The first thing you need to do is add Arquillian and Arquillian Cube dependencies on your build tool.

Then you can write the test which in this case tests that you can create a bucket and add some content using the S3 instance started in Docker host:

Important things to take into consideration:
  1. You annotate your test with Arquillian runner.
  2. Use @DockerContainer annotation to attribute used to define the container.
  3. Container Object DSL is just a DSL that allows you to configure the container you want to use. In this case the localstack container with required port binding information.
  4. The test just connects to Amazon S3 and creates a bucket and stores some content.
Nothing else is required. When you run this test, Arquillian Cube will connect to installed Docker (Machine) host and start the localstack container. When it is up and running and services are able to receive requests, the tests are executed. After that container is stopped and destroyed.

TIP1: If you cannot use Arquillian runner you can also use a JUnit Class Rule to define the container as described here

TIP2: If you are planning to use localstack in the whole organization, I suggest you to use Container Object approach instead of DSL because then you can pack the localstack Container Object into a jar file and import in all projects you need to use it. You can read at

So now you can write tests for your application running on AWS cloud without having to connect to remote hosts, just using local environment.

We keep learning,
Tú, tú eres el imán y yo soy el metal , Me voy acercando y voy armando el plan , Solo con pensarlo se acelera el pulso (Oh yeah) (Despacito - Luis Fonsi)

jueves, junio 22, 2017

Vert.X meets Service Virtualization with Hoverfly

Service Virtualization is a technique using to emulate the behaviour of dependencies of component-based applications.

Hoverfly is a service virtualisation tool written in Go which allows you to emulate HTTP(S) services. It is a proxy which responds to HTTP(S) requests with stored responses, pretending to be it’s real counterpart.

Hoverfly Java is a wrapper around Hoverfly, that let's you use it in Java world. It provides a native Java DSL to write expectations and a JUnit rule to use it together with JUnit.

But apart from being able to program expectations, you can also use Hoverfly to capture traffic between both services (in both cases are real services) and persist it.

Then in next runs Hoverfly will use these persisted scripts to emulate traffic and not touch the remote service. In this way, instead of programming expectations, which means that you are programming how you understand the system, you are using real communication data.

This can be summarised in next figures:

First time the output traffic is sent though Hoverfly proxy, it is redirected to real service and it generates a response. Then when the response arrives to proxy, both request and response are stored, and the real response is sent back to caller.

Then in next calls of same method:

The output traffic of Service A is still sent though Hoverfly proxy, but now the response is returned from previous stored responses instead of redirecting to real service.

So, how to connect from HTTP client of Service A to Hoverfly proxy? The quick answer is nothing.

Hoverfly just overrides Java network system properties ( so you don't need to do anything, all communications (independently of the host you put there) from HTTP client will  go through Hoverfly proxy.

The problem is what's happening if the API you are using as HTTP client does not honor these system properties? Then obviously all outgoing communications will not pass thorough proxy.

One example is Vert.X and its HTTP client io.vertx.rxjava.ext.web.client.WebClient. Since WebClient does not honor these properties, you need to configure the client properly in order to use Hoverfly.

The basic step you need to do is just configure WebClient with proxy options that are set as system properties.

Notice that the only thing that it done here is just checking if system properties regarding network proxy has been configured (by Hoverfly Java) and if it is the case just create a Vert.X ProxyOptions object to configure the HTTP client.

With this change, you can write tests with Hoverfly and Vert.X without any problem:

In previous example Hoverfly is used as in simulate mode and the request/response definitions comes in form of DSL instead of an external JSON script.
Notice that in this case you are programming that when a request by current service (VillainsVerticle), is done to host crimes and port 9090, using GET HTTP method at /crimes/Gru then the response is returned. For sake of simplicity of current post this method is enough.

You can see source code at and read about Hoverfly Java at

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