AssertJ Assertions Generator Gradle Plugin

A Gradle plugin that generates AssertJ assertion classes for your classes and packages.

The generateAssertions task runs after classes and before the test compilation tasks, and generated sources are added to the test source set automatically.

Requirements

• Gradle 8.5 or newer, tested 8.5–9.x (users on Gradle 7.x–8.4 should stay on plugin version 1.1.5)
• jakarta.annotation:jakarta.annotation-api on the test compile classpath, or a stack that includes it (e.g. Spring Boot 3+). See Generated annotations.

Quick start

plugins {
  id 'com.github.fhermansson.assertj-generator' version '2.0.1'
}

repositories { mavenCentral() }

dependencies {
  testImplementation 'org.assertj:assertj-core:3.27.7'
  testCompileOnly 'jakarta.annotation:jakarta.annotation-api:2.1.1'
}

assertjGenerator {
  classOrPackageNames = ['com.example.model']
}

Use any assertj-core version you like in your tests — the version the plugin uses internally (for generation only) is an implementation detail and does not constrain yours. Generated assertions compile against your test classpath.

Run ./gradlew test — assertions are generated, compiled, and available via the generated entry points, e.g. import static com.example.model.Assertions.assertThat;.

Generated annotations

Generated classes are annotated @jakarta.annotation.Generated. No JDK has shipped the javax.annotation class since Java 11, so the annotation always comes from a dependency — modern stacks (Jakarta EE 9+, Spring Boot 3+) already have it.

The annotation has SOURCE retention: it is needed only to compile the generated code (testCompileOnly is enough) and leaves no trace in bytecode or at runtime.

Properties

The assertjGenerator extension configures the generateAssertions task and provides defaults for additional tasks of type com.github.fhermansson.gradle.assertj.plugin.GenerateAssertions. All properties support = assignment in both Groovy and Kotlin DSL.

Property	Type	Default	Description
classOrPackageNames	ListProperty<String>	[]	Class or package names to generate assertions for
sourceSet	Property<SourceSet>	sourceSets.main	The sourceSet containing classes to generate assertions for. The task depends on its classes task.
testSourceSet	Property<SourceSet>	sourceSets.test	The target sourceSet. outputDir is added to its srcDirs, and its compileJava, compileKotlin and compileGroovy tasks depend on this task.
outputDir	DirectoryProperty	[buildDirectory]/generated/sources/assertj/[testSourceSet.name]	Where to put the generated classes
entryPointPackage	Property<String>	unset	Destination package for entry point classes. The generator derives it from the generated classes if unset
entryPointTypes	SetProperty<AssertionsEntryPointType>	['STANDARD']	Types of entry point classes to generate. Values: 'STANDARD', 'SOFT', 'BDD', 'JUNIT_SOFT', 'BDD_SOFT', 'JUNIT_BDD_SOFT', 'AUTO_CLOSEABLE_SOFT', 'AUTO_CLOSEABLE_BDD_SOFT'
entryPointInherits	Property<Boolean>	true	Entry point classes inherit from core AssertJ classes
cleanOutputDir	Property<Boolean>	true	Remove all files in outputDir before generating assertions
excludes	ListProperty<String>	[]	Regexes matched against fully qualified class names; matching classes are skipped
generateForNonPublicFields	Property<Boolean>	false	Generate assertions for non-public fields without public accessors as well

Multiple source sets

For each additional source set, register an extra task. Properties you set on the task win; unset task properties fall back to the assertjGenerator extension, and to plugin defaults if the extension does not set them either:

import com.github.fhermansson.gradle.assertj.plugin.GenerateAssertions

assertjGenerator {
  classOrPackageNames = ['com.example.model']
  entryPointTypes = ['STANDARD', 'SOFT']
}

tasks.register('generateOtherAssertions', GenerateAssertions) {
  classOrPackageNames = ['com.other.model']
  sourceSet = sourceSets.other
  testSourceSet = sourceSets.otherTest
}

This also works with source sets from other plugins, e.g. java-test-fixtures:

tasks.register('generateTestFixturesAssertions', GenerateAssertions) {
  sourceSet = sourceSets.testFixtures
}

Upgrading from 1.x

Three changes in 2.0.0:

1. The default outputDir moved from src/[testSourceSet.name]/generated-java to [buildDirectory]/generated/sources/assertj/[testSourceSet.name]. Generated sources now live under the build directory: nothing to commit or .gitignore, and gradle clean removes them. If you relied on the old location, set it explicitly:

assertjGenerator {
  outputDir = file('src/test/generated-java')
}

2. Generated classes are now annotated @jakarta.annotation.Generated (the useJakartaAnnotations option is gone — jakarta is always used). See Generated annotations.

3. The extension now uses Gradle's lazy Property types. = assignment works in both Groovy and Kotlin DSL; list-typed properties changed from arrays to lists, and outputDir is now a DirectoryProperty that takes files or directory providers.

4. If you have kotlinter lint/format workarounds for the generated directory (exclude { ... } and mustRunAfter/dependsOn on LintTask/FormatTask), remove them — they are no longer needed since 2.0.1: the generated sources directory is wired as a task output provider, so consuming tasks carry the dependency implicitly.