How to unit test a Spring Boot MongoRepository?

An update for 2018 and Spring Boot 2. First of all, you can have data-only integration tests with the embedded db as per the documentation. This uses the DataMongoTest annotation. This configures only the necessary dependencies that make mongoDB tests possible.

If you want to do full integration tests, add the AutoConfigureDataMongo annotation instead:

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.DEFINED_PORT)
@AutoConfigureDataMongo
public class PriceApiControllerIT {

Dependencies you should have in your pom.xml:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.1.RELEASE</version>
</parent>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-mongodb</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>de.flapdoodle.embed</groupId>
        <artifactId>de.flapdoodle.embed.mongo</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>