Unit Testing Spring Transaction Propagation: Practical Insights

Version and Environment

The tests are based on Spring Boot 3.2.4 with Spring Framework 6.x and require JDK 17+ . The Maven dependencies include Spring Boot starter, AOP, Data JPA, the H2 in‑memory database, and Spring Boot Test.

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>3.2.4</version>
</parent>
<dependencies>
    <!-- Spring Boot Starter -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <!-- Spring Boot AOP -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-aop</artifactId>
    </dependency>
    <!-- Spring Data JPA -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <!-- H2 Database -->
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <scope>runtime</scope>
    </dependency>
    <!-- Spring Boot Test -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

Test Class and Preconditions

The main test class TransactionPropagationTest uses JUnit 5 and Spring Boot Test. Preconditions are:

Spring Boot 3.2.4 + JDK 21

H2 in‑memory database ( jdbc:h2:mem:testdb)

JPA + Hibernate auto‑create tables

Each test method rolls back by default because of @Transactional on the test class

Test Cases – Propagation Behaviors

The suite contains ten test methods that cover the five standard propagation types and four typical failure traps, plus a solution using rollbackFor:

REQUIRED : child joins parent transaction; an exception rolls back the whole transaction.

REQUIRES_NEW : child runs in an independent transaction; parent rollback does not affect child data.

NESTED : child creates a savepoint; rolling back the child restores the savepoint while the parent can still commit.

SUPPORTS : joins a transaction if one exists; otherwise runs non‑transactionally.

MANDATORY : throws IllegalTransactionStateException when no surrounding transaction is present.

Self‑call trap : a this.xxx() call bypasses the AOP proxy, so REQUIRES_NEW does not take effect.

Swallowed exception trap : catching an exception prevents Spring from marking the transaction for rollback.

Checked‑exception trap : by default only RuntimeException triggers rollback; checked exceptions do not.

Non‑public method trap : @Transactional on a non‑public method is ignored.

Solution : adding @Transactional(rollbackFor = Exception.class) forces rollback for checked exceptions.

Auxiliary Classes

Supporting source files include: SpringContainerApplication – the boot entry point with @EnableJpaRepositories.

Application YAML configuring the H2 datasource, Hibernate DDL auto‑create, and SQL logging. TxTestEntity – a simple JPA entity with id and name fields. TxTestRepository – extends JpaRepository<TxTestEntity, Integer> and provides findByName and countByName.

Service beans for each propagation type ( RequiredService, RequiresNewService, NestedService, SupportsService, MandatoryService) that perform a simple repository.save(...) and optionally throw a RuntimeException.

Parent services ( ParentWithRequiresNewService, ParentWithNestedService, ParentWithSupportsService, ParentWithMandatoryService) that invoke the child services to demonstrate nested transaction behavior. SelfCallService – illustrates the proxy‑bypass problem and the exception‑swallowing scenario.

Running the Tests

Tests can be executed via Maven: mvn test -Dtest=TransactionPropagationTest or directly from IntelliJ IDEA by right‑clicking the test class or method and selecting “Run” or “Debug”.

Reference

The code accompanies the article “Spring Transaction Propagation Full Analysis”.