Archive: November 2022

Generic Derivation - a comparison

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Chiel van de Steeg

In a previous post I’ve shown how to build a minimal example of a random case class generator using the metaprogramming features of Scala 3. While investigating this topic, I naturally came upon multiple ways to do this. In this post I will elaborate on two other ways to build the same generator and pick my personal favorite.

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Gradle Goodness: Using Spock With JVM Test Suite Plugin

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Hubert Klein Ikkink

Spock is an awesome test framework for testing our Java or Groovy code. Spock itself is written with Groovy and provides a nice syntax to define our tests, or specifications in Spock terminology. To configure support for using Spock in our Gradle build is very easy with the JVM Test Suite plugin (included with the Java plugin). The plugin gives us a nice syntax to define different types of tests, for example integration tests, with their own source set, dependencies and configuration. To use Spock as testing framework we only have to use the method useSpock within a test configuration. The default version of Spock that is used is 2.1-groovy-3.0 when we use Gradle 7.6. If we want to use another version we can use a String parameter when we use the useSpock method with the version we want to use.

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Gradle Goodness: Set Test Framework Version Using Version Catalog With JVM Test Suite Plugin

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Hubert Klein Ikkink

Since Gradle 7.3 we can use the JVM Test Suite plugin to define in a declarative way tests for our build. For example adding integration tests with a new source set and dependencies becomes easier with this plugin. The plugin is automatically part of the Java plugin so we don’t have to define it explicitly in our build. Configuring the default test task can also be done using the syntax of the JVM TestSuite plugin. We can use several methods from the JvmTestSuite class in our configuration. For example if we want to use Spock as testing framework we can simply add the method useSpock in our build script. Or if we want to use the JUnit 5 Jupiter engine we can use useJUnitJupiter. These methods will add dependencies in the testImplementation configuration. There is a default version for the dependencies if we use the method without arguments. But we can also define the version as String argument for these methods. The version catalog for our project is the place to store version for our dependencies, so it would be nice if we could use the version defined in our version catalog as argument for the use<TestFramework> methods. We can reference the version very simple by using libs.versions.<version-key>. This will return the value we defined as version in our version catalog.

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Mastering Maven: Exclude Modules From Build

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Hubert Klein Ikkink

When we are working with a multi-module project in Maven we might want to exclude a module when we invoke a build command. We might only be interested in partially building some modules. We can use the command line option -pl or --projects to specify a list of modules that need to be in our build. But we can also use ! followed by the module name to exclude modules from our build.

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Gradle Goodness: Grouping Version Catalog Dependencies Into Bundles

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Hubert Klein Ikkink

The version catalog in Gradle is very useful to define a list of dependencies in one single place. In our build script we references dependencies from the version catalog using type safe accessors when we define a dependency for a configuration. Sometimes multiple dependencies belong to each other and are used in combination with each other. In the version catalog we can define bundles of such dependency groups. Instead of referencing each dependency individually we can reference a bundle from the version catalog in our build script. This keeps our build script cleaner and updating a bundle only needs a change in the version catalog.

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Gradle Goodness: Defining Plugin Versions Using Version Catalog

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Hubert Klein Ikkink

A version catalog in Gradle is a central place in our project where we can define dependency references with their version or version rules. A dependency reference is defined using an identifier with a corresponding dependency definition containing the coordinates of the dependency. Now we can reference the dependency using the identifier in for example a dependency configuration, e.g. implementation(libs.spring.core). If there is a version change we want to apply we only have to make the change in our version catalog. An added bonus is that Gradle generates type safe accessors for the identifier we use in our version catalog, so we can get code completion in our IntelliJ IDEA when we want to reference a dependency from the version catalog.

Besides dependencies we need to build and test our software we can also include definitions for Gradle plugins including their version.

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Clojure Goodness: Writing Text File Content With spit

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Hubert Klein Ikkink

In a previous post we learned how to read text file contents with the slurp function. To write text file content we use the spit function. We content is defined in the second argument of the function. The first argument allows several types that will turn into a Writer object used for writing the content to. For example a string argument is used as URI and if that is not valid as a file name of the file to read. A File instance can be used directly as argument as well. But also Writer, BufferedWriter, OutputStream, URI, URL and Socket. As an option we can specify the encoding used to write the file content using the :encoding keyword. The default encoding is UTF-8 if we don’t specify the encoding option. With the option :append we can define if content needs to be appended to an existing file or the content should overwrite existing content in the file.

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