Features

The Jackson plugin integrates Jackson with Fixture Monkey, giving you:

• JacksonObjectArbitraryIntrospector as the default introspector — creates objects using Jackson's ObjectMapper
• Jackson annotation support — @JsonProperty, @JsonIgnore, @JsonTypeInfo, @JsonSubTypes
• Custom ObjectMapper — use your production ObjectMapper configuration

When to use the Jackson Plugin

The Jackson plugin is a good choice when:

• Your classes use Jackson annotations (@JsonProperty, @JsonIgnore, etc.)
• You have a mix of Java and Kotlin classes in your project
• Your classes don't have a no-args constructor or Lombok annotations
• You want object creation to match your production serialization behavior

tip

If your classes have a no-args constructor with setters, the default BeanArbitraryIntrospector works fine without this plugin. For Lombok @Value classes, consider ConstructorPropertiesArbitraryIntrospector instead.

Dependencies

Gradle

testImplementation("com.navercorp.fixturemonkey:fixture-monkey-jackson:1.1.16")

Maven

<dependency>
  <groupId>com.navercorp.fixturemonkey</groupId>
  <artifactId>fixture-monkey-jackson</artifactId>
  <version>1.1.16</version>
  <scope>test</scope>
</dependency>

Plugin Setup

Java

FixtureMonkey fixtureMonkey = FixtureMonkey.builder()
    .plugin(new JacksonPlugin())
    .build();

Kotlin

val fixtureMonkey = FixtureMonkey.builder()
    .plugin(KotlinPlugin())
    .plugin(JacksonPlugin())
    .build()

note

For Kotlin projects, add both KotlinPlugin() and JacksonPlugin(). Also add jackson-module-kotlin to your dependencies for proper Kotlin class serialization.

Using a Custom ObjectMapper

If your production code uses a custom ObjectMapper, pass it to the plugin to ensure test objects match your serialization configuration:

Java

ObjectMapper objectMapper = JsonMapper.builder()
    .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
    .build();

FixtureMonkey fixtureMonkey = FixtureMonkey.builder()
    .plugin(new JacksonPlugin(objectMapper))
    .build();

Kotlin

val objectMapper = JsonMapper.builder()
    .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
    .build()

val fixtureMonkey = FixtureMonkey.builder()
    .plugin(KotlinPlugin())
    .plugin(JacksonPlugin(objectMapper))
    .build()

Quick Example

Java

@Value
public class Product {
    long id;

    @JsonProperty("name")
    String productName;

    long price;

    @JsonIgnore
    List<String> options;
}

@Test
void test() {
    FixtureMonkey fixtureMonkey = FixtureMonkey.builder()
        .plugin(new JacksonPlugin())
        .build();

    Product product = fixtureMonkey.giveMeBuilder(Product.class)
        .set("name", "book")  // uses @JsonProperty name
        .sample();

    then(product.getProductName()).isEqualTo("book");
    then(product.getOptions()).isNull();  // @JsonIgnore
}

Kotlin

data class Product(
    val id: Long,
    @JsonProperty("name")
    val productName: String,
    val price: Long,
    @JsonIgnore
    val options: List<String>? = null
)

@Test
fun test() {
    val fixtureMonkey = FixtureMonkey.builder()
        .plugin(KotlinPlugin())
        .plugin(JacksonPlugin())
        .build()

    val product = fixtureMonkey.giveMeBuilder<Product>()
        .set("name", "book")  // uses @JsonProperty name
        .sample()

    then(product.productName).isEqualTo("book")
    then(product.options).isNull()  // @JsonIgnore
}

Learn More

• JacksonObjectArbitraryIntrospector — how the introspector works and performance considerations
• Jackson Annotations — supported annotations and examples