kotlin-gradle-standalone-plugin

name: kotlin-gradle-standalone-plugin description: Develop and maintain standalone Gradle plugins implemented in Kotlin. Use when tasks involve creating a plugin module, defining plugin IDs, adding extensions/tasks, wiring lazy configuration with Provider APIs, writing Gradle TestKit coverage, or preparing plugin publication and compatibility updates.

Kotlin Gradle Standalone Plugin

Overview

Build production-grade standalone Gradle plugins in Kotlin with clear public DSL, lazy configuration, and testable task behavior. Prefer stable plugin APIs and Gradle TestKit for behavioral verification.

Core Workflow

1. Confirm scope: new plugin, feature change, bug fix, or publishing update.
2. Define plugin surface first:
   • Plugin ID(s)
   • Public extension DSL
   • Registered tasks and conventions
3. Implement plugin wiring with lazy configuration:
   • Use Property<T>, DirectoryProperty, RegularFileProperty, ListProperty<T>.
   • Avoid eager get() during configuration phase.
4. Keep API boundaries explicit:
   • Public DSL under dedicated package (e.g., dsl/).
   • Internal implementation in internal/.
5. Add/adjust tests:
   • Unit tests for pure logic.
   • Gradle TestKit tests for plugin behavior against sample builds.
6. Run narrow verification first, then broader checks.

Implementation Rules

• Use Plugin<Project> entrypoint with small apply body.
• Register tasks using tasks.register(...), not tasks.create(...).
• Configure tasks via providers (map, flatMap, convention) rather than immediate value resolution.
• Prefer deterministic task inputs/outputs and annotate task properties correctly.
• Use typed extensions for user-facing configuration.
• Do not leak internal types through public DSL.

Testing Rules

• Verify plugin behavior through real Gradle builds with TestKit.
• Assert task graph effects and generated outputs, not internal implementation details.
• Cover:
  • default configuration behavior
  • user-overridden DSL values
  • failure mode for invalid config
• Keep fixture builds minimal and explicit.

See these references as needed:

• references/gradle-plugin-kotlin-reference.md
• references/gradle-worker-api.md
• references/task-caching.md

Verification Commands

Run the smallest relevant command first:

./gradlew :<plugin-module>:test --tests "<FQN>"
./gradlew :<plugin-module>:functionalTest
./gradlew :<plugin-module>:check
./gradlew check

Completion Criteria

• Plugin ID, DSL, and task behavior are coherent and documented in code.
• Configuration is lazy and cache-friendly.
• TestKit coverage validates expected behavior and failure paths.
• Targeted checks pass for the changed plugin module.