Bean Validation

Generating valid data

Using the Jakarta Validation plugin, we can generate valid data based on Jakarta Bean validation annotations on properties.

For example, there can be a Product class annotated as follows:

@Value
public class Product {
    @Min(1)
    long id;

    @NotBlank
    String productName;

    @Max(100000)
    long price;

    @Size(min = 3)
    List<@NotBlank String> options;

    @Past
    Instant createdAt;
}

An instance of the Product class that is compliant with the annotations can be created in the following manner:

@Test
void test() {
    // given
    FixtureMonkey fixtureMonkey = FixtureMonkey.builder()
        .objectIntrospector(ConstructorPropertiesArbitraryIntrospector.INSTANCE)
        .plugin(new JakartaValidationPlugin())
        .build();

    // when
    Product actual = fixtureMonkey.giveMeOne(Product.class);

    // then
    then(actual).isNotNull();
    then(actual.getId()).isGreaterThan(0);
    then(actual.getProductName()).isNotBlank();
    then(actual.getPrice()).isLessThanOrEqualTo(100000);
    then(actual.getOptions().size()).isGreaterThanOrEqualTo(3);
    then(actual.getOptions()).allSatisfy(it -> then(it).isNotEmpty());
    then(actual.getCreatedAt()).isNotNull().isLessThanOrEqualTo(Instant.now());
}

Supported Annotations

Every annotation from the jakarta.validation.constraints package is supported. Different types support different annotation constraints.

Numeric Type

Supported Types: BigDecimal, BigInteger, byte, double, float, int, long, short

  • @Digits (fraction is currently not supported)
  • @Max
  • @Min
  • @Negative
  • @NegativeOrZero
  • @DecimalMax
  • @DecimalMin
  • @Positive
  • @PositiveOrZero

Boolean Type

  • @AssertFalse
  • @AssertTrue

String Type

  • @Null
  • @NotNull
  • @NotBlank
  • @NotEmpty
  • @Size
  • @Digits
  • @Pattern
  • @Email

Time Type

Supported Types: Calendar, Date, Instant, LocalDate, LocalDateTime, LocalTime, ZonedDateTime, Year, YearMonth, MonthDay, OffsetDateTime, OffsetTime

  • @Past
  • @PastOrPresent
  • @Future
  • @FutureOrPresent

Container Type

  • @Size
  • @NotEmpty
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