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Introduction

If you've recently explored the RAGE4J-Core documentation, you might be wondering: what exactly is RAGE4J-Assert?
RAGE4J-Assert serves as an intuitive and user-friendly wrapper for the RAGE4J-Core API. During our initial experiences writing tests with RAGE4J-Core, we noticed that the API could be quite cumbersome, even for crafting simple tests. Our goal with RAGE4J-Assert is to elevate the developer experience without sacrificing the power of the framework. With RAGE4J-Assert, writing tests becomes both quicker and more comfortable.

Simple Example​

import dev.langchain4j.model.openai.OpenAiChatModel;
import dev.rage4j.asserts.RageAssert;
import dev.rage4j.asserts.openai.OpenAiLLMBuilder;
import org.junit.jupiter.api.Test;

import static dev.langchain4j.model.openai.OpenAiChatModelName.GPT_4_O_MINI;

class RageAssertTest
{
	private final String key = System.getenv("OPEN_API_KEY");
	private final OpenAiChatModel model = OpenAiChatModel.builder()
		.apiKey(key)
		.modelName(GPT_4_O_MINI)
		.build();

	@Test
	void testCorrectnessApi()
	{
		RageAssert rageAssert = new OpenAiLLMBuilder().fromApiKey(key);
		rageAssert.given()
			.question("What is the capital of France?")
			.groundTruth("Paris is the capital of France")
			.when()
			.answer(q -> model.generate(q))
			.then()
			.assertAnswerCorrectness(0.7);
	}
}

Model Selection​

Configure custom models for chat and embedding operations:

RageAssert rageAssert = new OpenAiLLMBuilder()
    .withChatModel("gpt-4o")
    .withEmbeddingModel("text-embedding-3-large")
    .fromApiKey(key);

Default models: gpt-5.1 (chat), text-embedding-3-small (embedding).

Evaluation Mode​

By default, assertions throw exceptions on failure (strict mode). Enable evaluation mode to log warnings instead, allowing complete test runs for data collection:

RageAssert rageAssert = new OpenAiLLMBuilder()
    .fromApiKey(key)
    .withEvaluationMode();  // Logs warnings instead of throwing

// Switch back to strict mode if needed
rageAssert.withStrictMode();

Features​

You just saw the assertAnswerCorrectness feature in the example above. But that's not all — RAGE4J-Assert supports additional features from the core API, including:

  • assertFaithfulness(double minValue)
  • assertAnswerCorrectness(double minValue)
  • assertAnswerRelevance(double minValue)
  • assertSemanticSimilarity(double minValue)
  • asserBleuScore(double minValue)
  • assertRougeScore(double minValue, RougeScoreEvaluator.RougeType rougeType, RougeScoreEvaluator.MeasureType measureType) If you're eager to explore more examples, check out the examples on the next page! 😊