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When important data is written to STDIN/STDOUT and an application relies on specific system properties or environment variables, writing tests is getting more complicated. System Rules is a collection of JUnit rules that helps us writing Java tests for everything that deals with java.lang.System. In the following short examples I’d like to demonstrate how to deal with system properties, environment variables, STDOUT and STDERR and capturing both for testing e.g. for some golden master refactoring. ...

Setting up a larger application using dependency injection always requires us developers to set up our application’s object graph. Programming in Go there is a library that eases this task for us, offering a reflect based injector to set up the graph in a few steps, named facebookgo-inject. In the following article I’d like to demonstrate dependency injection using this library for a small sample application. Figure 1. Go dependency injection with facebookgo...

Learning the Go programming language, I wanted to implement an application that I had written with other languages and frameworks before to get a grip on this language. That’s why I tried to implement a really simple websocket chat server in Go and described my approach in the following article. Go Websocket Chat Implementation Writing the Chat Server Websocket Chat in Action ...

When it comes to writing microservices in Java, plenty of tools and frameworks exist. In the following tutorial, I’d like to demonstrate another minimalistic framework called Bootique by implementing a simple microservice exposing its functions either as a RESTful web-service or as a runnable command executed using the command line. Bootique Command Line Dependencies Using Maven here, we’re adding the following elements to our project’s pom.xml: Bootiques Bill of Materials as dependency management: bootique-bom Bootique Jersey for our REST service: bootique-jersey Bootique Logback for logging: bootique-logback Maven Shade Plugin to assemble our fat-jar ...

When building up search engines, indexing tons of data into a schema-less, distributed data store, Elasticsearch has always been a favourite tool of mine. In addition to its core features, it also offers tools and documentation for us developers when we need to write integration tests for our Elasticsearch powered Java applications. In the following tutorial I’d like to demonstrate how to implement a small sample application using Elasticsearch under the hood and how to write integration-tests with these tools for this application afterwards. ...

When integrating a Neo4j database into a Java application a developer often needs to map nodes and edges of the graph to corresponding Java classes of the domain model. Neo4j OGM eases this work and allows us to map our domain objects to the graph database using simple annotations – similar to the Java Persistence API (JPA) for relational database management systems. In the following tutorial I’d like to demonstrate how to use Neo4j OGM to build a simple train timetable planner and a permission system mapping between graph, nodes, edges and POJOs. ...

When writing applications that interchange information with LDAP directory services there is always the need to write integration tests for these components and services. Therefore we need a the possibility to start-up an embedded LDAP server, fill it with test-data and control its life-cycle during the test-phases. In the following tutorial I’d like to demonstrate two candidates that fulfil this purpose, the ApacheDS test integrations and a small library named embedded-ldap-junit. ...

Atlassian has added a continuous integration service as a new feature to their GitHub Cloud product. It’s called GitHub Pipelines and it is similar to Travis CI for GitHub offering a nice integration for continuous integration/delivery pipelines for projects hosted on GitHub. It’s still in the beta phase and requires a sign-up but nevertheless I’d like to demonstrate the current state of this service and how easy it is to add scripted pipelines to a project. ...

The MQ Telemetry Transport Protocol (MQTT) is a lightweight publish/subscribe messaging protocol developed in 1999 that experiences a growing popularity due to trends like the Internet-of-Things and the need to exchange information between low powered devices with aspects as CPU and bandwidth usage in mind. In the following tutorial I’d like to demonstrate how to set-up a broker for this protocol with the help of the Moquette library and how to create a client and publish messages for a specific topic using this broker and Eclipse Paho as client library. ...

Writing tests not only to verify the behaviour of a web site but also the correctness of its layout especially for responsive websites is not always easy. Luckily the Galen Framework eases the task of writing layout tests for us, offering a specialized domain-specific-language to write layout-specifications, it integrates well with Selenium Grid, Sauce Labs or BrowserStack, it offers an easy way to deal with different browser sizes and responsive designs and it generates nice, detailed test reports. ...