Testing Graph Use Cases

import java.util.List;

import org.springframework.data.neo4j.repository.Neo4jRepository;

public interface AccountRepository extends Neo4jRepository<Account, String> {

    List<Account> findByFlaggedTrue();
}

import static org.assertj.core.api.Assertions.assertThat;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.data.neo4j.test.autoconfigure.DataNeo4jTest;
import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
import org.testcontainers.junit.jupiter.Container;
import org.testcontainers.junit.jupiter.Testcontainers;
import org.testcontainers.neo4j.Neo4jContainer;

@Testcontainers
@DataNeo4jTest
class AccountRepositoryTest {

    @Container
    @ServiceConnection
    static final Neo4jContainer NEO4J = new Neo4jContainer("neo4j:2026.10.1");

    @Autowired
    AccountRepository accounts;

    @Test
    void findsFlaggedAccounts() {
        accounts.save(new Account("A1", true, null, null));
        accounts.save(new Account("A2", false, null, null));

        assertThat(accounts.findByFlaggedTrue()).extracting(Account::getAccountNumber).containsExactly("A1");
    }
}

import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
import org.testcontainers.junit.jupiter.Container;
import org.testcontainers.junit.jupiter.Testcontainers;
import org.testcontainers.neo4j.Neo4jContainer;

@Testcontainers
@SpringBootTest
class FraudDetectionIT {

    @Container
    @ServiceConnection
    static final Neo4jContainer NEO4J = new Neo4jContainer("neo4j:2026.10.1")
        .withEnv("NEO4J_PLUGINS", "[\"graph-data-science\", \"apoc\"]");

    // tests autowire the application beans
}

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;

import org.springframework.core.io.ClassPathResource;
import org.springframework.data.neo4j.core.Neo4jClient;
import org.springframework.stereotype.Component;

@Component
class GraphFixtures {

    private final Neo4jClient client;

    GraphFixtures(Neo4jClient client) {
        this.client = client;
    }

    void reset() {
        dropAllProjections();
        client.query("MATCH (n) DETACH DELETE n").run();
    }

    void load(String script) throws IOException {
        var text = new ClassPathResource(script).getContentAsString(StandardCharsets.UTF_8);
        Arrays.stream(text.split(";"))
            .map(String::strip)
            .filter(statement -> !statement.isEmpty())
            .forEach(statement -> client.query(statement).run());
    }

    private void dropAllProjections() {
        client.query("""
                CALL gds.graph.list() YIELD graphName
                CALL gds.graph.drop(graphName, false) YIELD graphName AS dropped
                RETURN count(dropped) AS dropped
                """)
            .fetch()
            .all();
    }
}

import static org.assertj.core.api.Assertions.assertThat;

import java.util.List;
import java.util.Map;

import org.junit.jupiter.api.Test;

class CommunityAssertionsTest {

    @Test
    void ringsAreSeparatedWhateverTheCommunityIds() {
        Map<String, Long> communityByAccount = loadCommunities();

        // only what the reference states: the two rings are separate communities;
        // where A7 lands and how many communities there are is not asserted
        assertThat(communityByAccount.get("A1"))
            .isEqualTo(communityByAccount.get("A2"))
            .isEqualTo(communityByAccount.get("A3"));
        assertThat(communityByAccount.get("A4"))
            .isEqualTo(communityByAccount.get("A5"))
            .isEqualTo(communityByAccount.get("A6"));
        assertThat(communityByAccount.get("A1")).isNotEqualTo(communityByAccount.get("A4"));
    }

    @Test
    void highestBetweennessIsTheBridgeAccount() {
        List<String> ranking = accountsByScoreDescending();

        assertThat(ranking.get(0)).isEqualTo("A4");
    }

    private Map<String, Long> loadCommunities() {
        return Map.of(); // reads the property written by the job
    }

    private List<String> accountsByScoreDescending() {
        return List.of(); // reads the scores written by the job, ordered in Cypher
    }
}

import org.springframework.boot.test.context.TestConfiguration;
import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
import org.springframework.context.annotation.Bean;
import org.testcontainers.neo4j.Neo4jContainer;

@TestConfiguration(proxyBeanMethods = false)
public class Neo4jTestContainerConfig {

    @Bean
    @ServiceConnection
    Neo4jContainer neo4j() {
        return new Neo4jContainer("neo4j:2026.10.1")
            .withEnv("NEO4J_PLUGINS", "[\"graph-data-science\", \"apoc\"]");
    }
}