OpenSkillIndex← back to search
claude-code

Agent-skills-standard java-testing

Testing standards using JUnit 5, AssertJ, and Mockito for Java. Use when writing or reviewing Java unit tests, setting up parameterized tests, writing integration tests with Testcontainers, or working with Mockito mocks. (triggers: **/*Test.java, **/*IT.java, @Test, @ParameterizedTest, Mockito, AssertJ, assertThat, JUnit, Testcontainers)

install
source · Clone the upstream repo
git clone https://github.com/HoangNguyen0403/agent-skills-standard
Claude Code · Install into ~/.claude/skills/
T=$(mktemp -d) && git clone --depth=1 https://github.com/HoangNguyen0403/agent-skills-standard "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/java/java-testing" ~/.claude/skills/hoangnguyen0403-agent-skills-standard-java-testing && rm -rf "$T"
manifest: skills/java/java-testing/SKILL.md
source content

Java Testing Standards

Priority: P0 (CRITICAL)

Implementation Guidelines

  • JUnit 5 (Jupiter): Use 
    @Test
    , 
    @BeforeEach
    , and 
    @AfterEach
    . Avoid JUnit 4 classes.
  • Fluent Assertions: Use 
    AssertJ (assertThat)
     over JUnit 
    assertEquals
    — enhanced readability.
  • Naming: Use 
    MethodName_State_Result
     or 
    @DisplayName("Check if X when Y")
    .
  • Parameterized Tests: Use 
    @ParameterizedTest
     with 
    @ValueSource
    , 
    @CsvSource
    , or 
    @MethodSource
    .
  • Mocking Strategy: Use 
    Mockito
     with 
    @ExtendWith(MockitoExtension.class)
    (JUnit 5). Use 
    @Mock
    , 
    @Spy
    , and 
    @InjectMocks
    . NEVER mock data-only Records.
  • Integration Testing: Use 
    Testcontainers
     with 
    @Container
    annotation for real databases (PostgreSQL/Redis) in integration tests (
    *IT.java
    ).
  • Isolation: Each test method MUST isolated and independent; use 
    @DirtiesContext
     sparingly.
  • AssertJ Chaining: Chain assertions for clarity: 
    assertThat(result).isNotNull().hasSize(2).contains("X")
    .
  • Mocking verification: Use 
    verify(mock, times(1)).method()
     to audit side-effects.
  • Exceptions: Use 
    assertThatThrownBy(() -> ...)
     to verify specific Exception types and messages.

Anti-Patterns

  • No Logic in Tests: Keep tests declarative; no loops or if/else branching.
  • No System.out in Tests: Use assertions; never print to stdout.
  • No Legacy Assertions: Use 
    assertThat(a).isEqualTo(b)
    , not 
    assertTrue(a == b)
    .
  • No Shared State: Tests must isolated and order-independent.

References