Build Helper Maven Plugin - Mincong Huang

Overview

In this article, I will explain how to set up additional source directory (src/it/java) and resource directory (src/it/resources) for integration tests in Maven project using Build Helper Maven Plugin. After reading this article, you will understand:

Why using Build Helper Maven Plugin?
How to declare Build Helper Maven Plugin?
How to observe changes?
How to go further in this topic?

Let’s get started.

Motivation

Traditionally, source code and resources are stored in src/main/{java,resources}, test sources and resources are stored in src/test/{java,resources}. This is part of the Maven Standard Directory Layout. However, in enterprise-level projects, having them might not be enough anymore: you might want to have a separated layout for unit tests, integration tests, functional tests, code generation, benchmarks, … depending on your requirements. Having a clear separation means:

Clear separation of responsibility
Trigger part of the sources in IDE (e.g. only running unit tests)

Here’re some directory layouts we can imagine:

Directory	Description
`src/it/{java,resources}`	Integration tests
`src/benchmark/{java,resources}`	Benchmarks

Build Helper Maven Plugin helps you to achieve this with a minimum of configuration.

Declaration

To use the Build Helper Maven Plugin, you need to declare it in the plugin management section of your POM file (pom.xml):

<pluginManagement>
  <plugins>
    <plugin>
      <groupId>org.codehaus.mojo</groupId>
      <artifactId>build-helper-maven-plugin</artifactId>
      <version>3.0.0</version>
    </plugin>
  </plugins>
</pluginManagement>

Then configure the executions in the plugin section.

<plugins>
  <plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>build-helper-maven-plugin</artifactId>
    <executions>
      <!-- see next sections in the blog -->
    </executions>
  </plugin>
</plugins>

Add Test Sources

Adding test sources is done by goal add-test-source of the plugin. Declare execution called “add-it-test-source” which executes this goal to include directory src/it/java as source directory.

<execution>
  <id>add-it-test-source</id>
  <goals>
    <goal>add-test-source</goal>
  </goals>
  <configuration>
    <sources>
      <source>src/it/java</source>
    </sources>
  </configuration>
</execution>

By default, goal “add-test-source” binds to the lifecycle phase: generate-test-sources. Running mvn verify or similar commands, you can see the following output in your console:

[INFO] --- build-helper-maven-plugin:3.0.0:add-test-source (add-it-test-source) @ build-helper-maven-plugin-demo ---
[INFO] Test Source directory: /Users/mincong/github/maven-demo/build-helper-maven-plugin/src/it/java added.

Add Test Resources

Adding test resources is done by goal add-test-resource of the plugin. Declare execution called “add-it-test-resource” which executes this goal to include directory src/it/resources as a resource directory. Note that the <resource> element is slightly different from <source>, where you need <directory> to include the desired directory.

<execution>
  <id>add-it-test-resource</id>
  <goals>
    <goal>add-test-resource</goal>
  </goals>
  <configuration>
    <resources>
      <resource>
        <directory>src/it/resources</directory>
      </resource>
    </resources>
  </configuration>
</execution>

By default, goal “add-test-resource” binds by default to the lifecycle phase: generated-test-resources. Running mvn verify or similar commands, you can see the following output in your console:

[INFO] --- build-helper-maven-plugin:3.0.0:add-test-resource (add-it-test-resource) @ build-helper-maven-plugin-demo ---
[INFO]
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ build-helper-maven-plugin-demo ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/mincong/github/maven-demo/build-helper-maven-plugin/src/test/resources
[INFO] Copying 1 resource

Conclusion

In this post, we see how to set additional source directory (src/it/java) and resource directory (src/it/resources) for integration tests in Maven project using Build Helper Maven Plugin. The same approach can be used for setting up benchmarks (src/benchmark) or any similar Maven layout. The source code in this post is available on GitHub. Interested to know more? You can subscribe to the feed of my blog, follow me on Twitter or GitHub. Hope you enjoy this article, see you the next time!