unit-test-bean-validation

Unit testing Jakarta Bean Validation constraints and custom validators without Spring context. This skill provides executable patterns for unit testing Jakarta Bean Validation annotations and custom validators using JUnit 5. Covers built-in constraints ( @NotNull , @Email , @Min , @Max , @Size ), custom @Constraint implementations, cross-field validation, and validation groups. Tests run in isolation without Spring context. For custom constraint patterns, see references/custom-validators.md : For validation groups and parameterized tests, see references/advanced-patterns.md : ValidatorFactory not found : Ensure jakarta.validation-api and hibernate-validator are on test classpath. Custom validator not invoked : Verify @Constraint(validatedBy = YourValidator.class) annotation is correct. Null values pass validation : This is expected behavior — constraints ignore null unless @NotNull is present. Wrong violation count : Use hasSize() to verify exact count, check all fields in the object.