152-java-performance-gatling

name	152-java-performance-gatling
description	Use when you need to set up Gatling performance testing for a Java Maven project — including adding Gatling dependencies and the Gatling Maven plugin, creating Java simulations, running gatling:test, configuring a simulation class, and reviewing generated reports. This should trigger for requests such as Add Gatling performance testing; Apply Gatling performance testing; Create a Gatling simulation; Add Gatling support; Review Gatling performance test assertions and feeders. Part of Plinth Toolkit
license	Apache-2.0
metadata	{"author":"Juan Antonio Breña Moral","version":"0.18.0"}

Run performance tests based on Gatling

Provide a complete Gatling performance testing setup for Java Maven projects by adding the required test dependencies and Gatling Maven plugin configuration, creating or guiding Java simulation placement, and explaining how to run simulations and inspect reports.

What is covered in this Skill?

• Add Gatling dependencies and the gatling-maven-plugin to pom.xml
• Project structure: src/test/java for Java simulations and src/test/resources for Gatling configuration, feeders, templates, and logging
• Run simulations with ./mvnw gatling:test
• Select a simulation with -Dgatling.simulationClass=<FullyQualifiedClassName> when multiple simulations exist
• Use ./mvnw gatling:help -Ddetail=true -Dgoal=test to inspect available plugin options
• Review generated Gatling run output and reports under the build output directory

Scope: Use Gatling through the Maven plugin for Java simulations. Prefer project-local Maven wrapper commands when available.

Constraints

Gatling setup must be Maven-based, reproducible, and compatible with Java project conventions. Prefer official Gatling Maven plugin behavior and avoid inventing unsupported command-line options.

• PREREQUISITE: Verify the project is Maven-based and prefer ./mvnw when the Maven wrapper exists
• BUILD CONFIGURATION: Add Gatling dependencies with test scope and configure io.gatling:gatling-maven-plugin in pom.xml
• VERSION SELECTION: Use the project's existing dependency/version-management pattern; if no Gatling versions are present, ask before pinning versions or use placeholders that require replacement
• SIMULATION LOCATION: Place Java simulations under src/test/java using an appropriate package name
• RESOURCE LOCATION: Place Gatling resources such as gatling.conf, feeders, request-body templates, and Logback test configuration under src/test/resources
• BEFORE APPLYING: Read the reference for setup, execution, and verification guidance
• EDGE CASE: If the project is not Maven-based, stop and explain that this skill targets Maven projects before suggesting Gradle or sbt alternatives
• EDGE CASE: If multiple simulations exist, configure or pass -Dgatling.simulationClass=<FullyQualifiedClassName> for non-interactive execution

When to use this skill

• Add Gatling performance testing
• Apply Gatling performance testing
• Create a Gatling simulation
• Add Gatling support
• Review Gatling performance test assertions and feeders

Workflow

1. Inspect the Maven project

Check for pom.xml, the Maven wrapper, existing test dependencies, dependency management, plugin management, and any existing Gatling configuration.

2. Add Gatling build configuration

Add the Gatling test dependency and io.gatling:gatling-maven-plugin using the project's existing version and plugin configuration style.

3. Create or adapt Java simulations

Create Java simulation classes under src/test/java or adapt existing simulations, keeping scenario names, base URLs, injection profiles, and assertions explicit.

4. Configure resources

Add optional Gatling resources under src/test/resources, including gatling.conf, feeders, request body templates, and logback-test.xml only when the project needs them.

5. Run and explain Gatling execution

Use ./mvnw gatling:test to run simulations and -Dgatling.simulationClass=<FullyQualifiedClassName> when a specific simulation must be selected.

6. Verify reports and next steps

Confirm the Gatling run completed, point to the generated report location from the command output, and summarize any failed assertions or performance findings.

Reference

For detailed guidance, examples, and constraints, see references/152-java-performance-gatling.md.