This year marks the 10th anniversary of the Fronteers conference , held at Pathé Tuschinski in Amsterdam. A single track conference covering various topics of frontend development. The JDriven delegation this year consists of Patrick Ooteman, Auke Speksnijder and Martijn van der Wijst. Topics are: VR, Animations, Developer tools, Caching, a11y, and WebAssembly. The talks didn’t just cover javascript, CSS and HTML. Also relating subjects like writing better language, tackling imposter syndrome and Japanese culture came by. There even was a separate talk focused on emojis :) We’ll try to summarize the nicest takeaways from the past couple of days.

From time to time you only want to run one test, one test method, one class or one package from the command-line. Or on the contrary: you want to exclude / ignore one specific test or group of tests during the build cycle. Excluding tests from the build cycle by the command line usually occurs when the following scenarios meet:

With Asciidoctor markup we can position images in our document. We can even float images, so text can next to an image, inside only below or about the image. We can also define multiple images to float, so the images are displayed on the same line next to each other. Any text that follows these images is also displayed next to the images. If we want only to have floating images, but the text starting under the images we can place the images inside an open block and assign the block the role float-group.

In the next example we first define three images that all have roles to float left. In the second part we group these images using the role float-group, so the text will not be displayed next to the images, but under the images:

In a previous post we learned how to use data in CSV and DSV format. Recently we can also include tab separated values (TSV) in a Asciidoctor table. We must set the table attribute format to the value tsv. The data can be inside the document, but also defined in an external file which we add with the include macro.

In the following example markup we have a table with inline tab separated values. A second table includes an external file with tab delimited values:

As a developer sooner or later you will encounter bugs, be it small ones or production breaking bugs. Now it is your task to find and fix the bug as soon as possible. In this article I will list the techniques I learned over the course of many years debugging web applications in the hope that it will help you be better and more efficient in bug hunting.

Op de eerste volledige conferentie dag van JavaOne stond natuurlijk meteen de keynote gepland. Het eerste gedeelte van de keynote werd verzorgd door de hoofdsponsor Intel en was best vermakelijk al lag de salespitch er wel dik bovenop. Intel lanceerde 2 opensource producten voor de Java community:

When we write a list in Asciidoctor we can simply create a list item by starting the line with a dot (.). To create a another list item we simply start a new line with a dot (.). But what if we want to add a list item with multiple paragraphs, or text and a source code block element. We can use the list item continuation (+) to indicate to Asciidoctor we want to keep these together for a single list item.

In the following example we have a list in Asciidoctor markup. The second list item has multiple paragraphs , the third item has an extra admonition block and the fourth item contains a source code block:

Writing a parameterized specification in Spock is easy. We need to add the where: block and use data providers to specify different values. For each set of values from the data providers our specifications is run, so we can test for example very effectively multiple input arguments for a method and the expected outcome. A data provider can be anything that implements the Iterable interface. Spock also adds support for a data table. In the data table we define columns for each variable and in the rows values for each variable. Since Spock 1.1 we can reuse the value of the variables inside the data provider or data table. The value of the variable can only be reused in variables that are defined after the variable we want to reuse is defined.

In the following example we have two feature methods, one uses a data provider and one a data table. The variable sentence is defined after the variable search, so we can use the search variable value in the definition of the sentence variable.

We all know writing tests or specifications with Spock is fun. We can run our specifications and when one of our assertions in a feature method invalid, the feature method is marked as failed. If we have more than one assertion in our feature method, only the first assertion that fails is returned as an error. Any other assertion after a failing assertion are not checked. To let Spock execute all assertions and return all failing assertions at once we must use the verifyAll method. We pass a closure with all our assertions to the method. All assertions will be checked when use the verifyAll and if one or more of the assertions is invalid the feature method will fail.

In the following example specification we have 3 assertions in the feature method check all properties are valid. We don’t use the verifyAll method in our first example.