---

A lightweight Gradle plugin for enforcing package dependency rules in Android & Kotlin projects. Define which packages can import from others within your project and enforce it automatically.

Structural is intended to be a quick way to enforce a modular architecture when other tools are not preferred or available. However, it can also be used for other purposes such as just forbidding one local package from importing from another.

Installation

---

plugins {
    id("com.adrianczuczka.structural") version "[version]"
}

repositories {
    mavenCentral()
}

Usage

---

Set the structure

Structural requires a YAML file to understand the intended package structure. First, create a YAML file in your project. You can link it like this:

structural {
    config = "./structural.yml"
}

If you omit this, it will look for a structural.yml file by default in the root directory.

In your YAML file, there should be two main sections: packages and rules. packages should be a list of all package names that Structural should check. For example, if you follow MVVM and Clean Architecture rules, your list could look like this:

packages:
  - local
  - remote
  - data
  - domain
  - ui

These are all the packages that will have rules related to which ones can import from which others.

The rules section should specify the rules which govern the package structure. There are two ways to write these rules. You can either use arrows to specify the relationships, like this:

rules:
  - data <- domain -> ui
  - local <- data
  - remote <- data

This means that

1. The data and ui folders can import from the domain folder, but not vice versa
2. The local and remote folders can import from the data folder, but not vice versa

The same rules can also be written like this:

rules:

  # YAML lists are supported
  ? [ ui, data ]
    :
    - domain

  ? [ local, remote ]
    :
    - data

  # Also works
  ui:
    - domain
  data:
    - domain
  local:
    - data
  remote:
    - data

Run the check

To check the validity of your module's folder structure, run:

./gradlew structuralCheck

An example result will look like this:

Setting a baseline

To ignore certain issues, you can run this command:

./gradlew structuralGenerateBaseline

This will create a baseline file containing all current issues, which will be ignored on subsequent checks. By default, the baseline will be created in $rootDir/baseline.xml. To set a custom path, you can add this property:

structural {
    baseline = "./baseline.xml"
}

Compatibility

This plugin is currently compatible up to Kotlin 2.0.0.