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Sometimes I need to resolve Maven dependencies programmatically. Eclipse Aether is a library for working with artifact repositories and I’ll be using it in the following example to read dependency trees from a given POM descriptor file and download each dependency from a remote Maven repository to a local directory. Figure 1. Using Eclipse Aether. Dependencies We’re adding a bunch of dependencies to our project’s pom.xml: <properties> <aetherVersion>1.1.0</aetherVersion> <mavenVersion>3.2.1</mavenVersion> </properties> ...

With JUnit 5 the possibilities to write parameterized tests have changed and improved a lot. The following short overview covers all new types of possible parameter sources for JUnit 5 tests as well as the new conversion API for test arguments. In addition we’re showing how parameterized tests were written in JUnit 4. Figure 1. Running JUnit5 in IntelliJ About We will be covering all available types of parameter sources in the following sections – all that you need as a prerequisite is Java ™, Maven and a few minutes of your time. ...

Maintaining architecture rules and constraints for a specific software project or an application is not easy as textual documentation is easily forgotten after a while and hard to verify. ArchUnit is a testing library that allows developers and software architects to write down such rules as executable tests that may be run by the development teams and the integration servers. In the following article I will demonstrate the basic features of this library by applying rules and constraints to an existing application. ...

In our tests we often need to create a bunch of test-objects that are populated with random-data. This data needs to follow specific rules as identifiers need to be unique or must be incremented, string-properties must follow special conventions and so on. In the following short tutorial I will demonstrate how to generate such test data using the Fixture Factory library. Figure 1. Fixture Factory and JUnit...

Google’s Macaroons are a mechanism to establish distributed authorization. The distinction to the classical bearer-token is their ability that they may be used to perform an action under certain restrictions and may then be used to create a new macaroon with stricter restrictions. The following short tutorial demonstrates how to create macaroons, serialize and deserialize them, add first- and third-party caveats and finally to verify them. Figure 1. jmacaroons example...

Playing around with the new module system in Java 9 I simply wanted to write down how to achieve the most basic tasks. Therefore I created the following module how-to based upon a simple demonstration project consisting of two dependant modules. Figure 1. Modules Component-Diagram Prerequisites and Setup We need an early access build of the Java ™ 9 JDK, available for download here. In addition we should make sure, that our environment variable JAVA_HOME is set to the corresponding directory and calling java -version returns something similar to this: ...

There is a new testing framework out there called Karate that is build on top of the popular Cucumber framework. Karate makes it easy to script interactions with out web-services under test and verify the results. In addition it offers us a lot of useful features like parallelization, script/feature re-use, data-tables, JsonPath and XPath support, gherkin syntax, switchable staging-configurations and many others. In the following tutorial we’ll be writing different scenarios and features for a real-world RESTful web-service to demonstrate some of its features. ...

Drools is a slim Business Rules Management System (BRMS) solution with different integrations and tools available. In the following short snippet I’d like to demonstrate how to integrate a simple rule engine into an application using this library. Figure 1. Drools Example running in Eclipse IDE Dependencies Using Gradle here we only need to add one dependency for drools-compiler to our project’s build.gradle. In addition, we’re adding a task to execute our application. ...

When dealing with remote services or APIs there is always the risk of latency issues, failures or connection losses. The worst thing to happen is when the remote service is down and our application hangs until the underlying protocol’s (e.g. TCP) connection timeout is reached and we’re receiving an exception. Until this moment is reached, our application might hang, memory is allocated for threads or bound objects and at last, our continuous requests might prevent the remote system from recovering. ...

When it comes to web-services (especially RESTful web-services), configuration files or other data-descriptors, the JavaScript Object Notation, short: JSON is often used as format of choice. As the task arises to transform these JSON structures, I have seen a variety of different approaches from converting JSON into XML using JAX-B, applying XSLT, transforming into JSON again on the one hand to loading JSON structures into Hash-maps of Hash-maps (..) and manually removing single elements from these collections on the other hand. ...