Unit Test Bean Validation

What it does

When your agent uses it

• Writing validation tests
• Bean validation tests
• Testing custom constraint validators

Example prompts

• “Use the unit-test-bean-validation skill to provide patterns for unit testing Jakarta Bean Validation (JSR-380), including @Valid, @NotNull, @Min…”
• “/unit-test-bean-validation”

Requirements

• Pre-approved tools (allowed-tools): Read, Write, Bash, Glob, Grep

Workflow steps

8 steps, taken from the first numbered list in SKILL.md.

1. 1Add dependencies: Include jakarta.validation-api and hibernate-validator in test scope
2. 2Create base test class: Build Validator once in @BeforeEach using Validation.buildDefaultValidatorFactory()
3. 3Test valid cases first: Verify objects pass without violations
4. 4Test invalid cases: Assert constraint violations include correct property path and message
5. 5Extract violation details: Use getPropertyPath(), getMessage(), getInvalidValue()
6. 6Test custom validators: See references/custom-validators.md for patterns
7. 7Use parameterized tests: Test multiple inputs efficiently with @ParameterizedTest
8. 8Group validation tests: Use validation groups for conditional rules (see references/advanced-patterns.md)

What it can do on your machine

Read from SKILL.md and the folder at commit fe73fb3. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Write
  • Bash
  • Glob
  • Grep

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are java and xml).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • jakarta.ee
  • hibernate.org

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Unit Test Bean Validation loads about 1.8k tokens when it runs, and up to ~3.4k if it reads all its reference files. Until then it costs about 114 tokens; SKILL.md has 509 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~114

When it runs · the whole SKILL.md, loaded when a task matches

~1.8k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~3.4k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

• NotePre-approves every shell command (allowed-tools: Bash)SKILL.md

  allowed-tools: Read, Write, Bash, Glob, Grep

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from giuseppe-trisciuoglio/developer-kit at commit fe73fb3, republished under its MIT licence (© giuseppe-trisciuoglio). 509 words, ~1,794 tokens.

name

unit-test-bean-validation

description

Provides patterns for unit testing Jakarta Bean Validation (JSR-380), including @Valid, @NotNull, @Min, @Max, @Email constraints with Hibernate Validator. Generates custom validator tests, constraint violation assertions, validation groups, and parameterized validation tests. Validates data integrity logic without Spring context. Use when writing validation tests, bean validation tests, or testing custom constraint validators.

allowed-tools

Read, Write, Bash, Glob, Grep

<dependency>
  <groupId>jakarta.validation</groupId>
  <artifactId>jakarta.validation-api</artifactId>
</dependency>
<dependency>
  <groupId>org.hibernate.validator</groupId>
  <artifactId>hibernate-validator</artifactId>
  <scope>test</scope>
</dependency>
<dependency>
  <groupId>org.assertj</groupId>
  <artifactId>assertj-core</artifactId>
  <scope>test</scope>
</dependency>

import jakarta.validation.*;
import jakarta.validation.ConstraintViolation;
import jakarta.validation.path.Path;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import static org.assertj.core.api.Assertions.*;

class BaseValidationTest {
  protected Validator validator;

  @BeforeEach
  void setUpValidator() {
    validator = Validation.buildDefaultValidatorFactory().getValidator();
  }
}

class UserDtoTest extends BaseValidationTest {

  @Test
  void shouldPassValidationWithValidUser() {
    UserDto user = new UserDto("Alice", "alice@example.com", 25);
    assertThat(validator.validate(user)).isEmpty();
  }

  @Test
  void shouldFailWhenNameIsNull() {
    UserDto user = new UserDto(null, "alice@example.com", 25);
    assertThat(validator.validate(user))
      .extracting(ConstraintViolation::getMessage)
      .contains("must not be blank");
  }

  @Test
  void shouldFailWhenEmailIsInvalid() {
    UserDto user = new UserDto("Alice", "invalid-email", 25);
    Set<ConstraintViolation<UserDto>> violations = validator.validate(user);
    assertThat(violations)
      .extracting(ConstraintViolation::getPropertyPath)
      .extracting(Path::toString)
      .contains("email");
  }

  @Test
  void shouldFailWhenAgeIsBelowMinimum() {
    UserDto user = new UserDto("Alice", "alice@example.com", -1);
    assertThat(validator.validate(user))
      .extracting(ConstraintViolation::getMessage)
      .contains("must be greater than or equal to 0");
  }

  @Test
  void shouldFailWhenMultipleConstraintsViolated() {
    UserDto user = new UserDto(null, "invalid", -5);
    assertThat(validator.validate(user)).hasSize(3);
  }
}

© giuseppe-trisciuoglio, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 2 other files (references) in plugins/developer-kit-java/skills/unit-test-bean-validation of giuseppe-trisciuoglio/developer-kit.

• SKILL.md
• references/advanced-patterns.md
• references/custom-validators.md

Open the folder on GitHubat commit fe73fb3