Test Analysis Extensions

Java Test Frameworks Reference (JUnit 4, JUnit 5 / Jupiter, TestNG)

Reference data for analyzing Java test code. Used by the polyglot test analysis skills.

Capability tags

Test File Identification

Assertion APIs

TestNG quirk: Assert.assertEquals(actual, expected) reverses the argument order vs JUnit. Misordered arguments are a common smell.

Third-party libraries: AssertJ (assertThat), Hamcrest (assertThat(x, is(y))), Truth (Google), Mockito (verify(mock).method(...)).

Sleep/Delay Patterns

Flag raw Thread.sleep in tests as Sleepy Test. Awaitility-based waits are acceptable.

Skip/Ignore Annotations

Exception Handling — Idiomatic Alternatives

// JUnit 5 (preferred):
InvalidOrderException ex = assertThrows(
    InvalidOrderException.class,
    () -> service.placeOrder(emptyOrder));
assertEquals("Order must contain at least one item", ex.getMessage());

// AssertJ:
assertThatThrownBy(() -> service.placeOrder(emptyOrder))
    .isInstanceOf(InvalidOrderException.class)
    .hasMessageContaining("at least one item");

// TestNG:
@Test(expectedExceptions = InvalidOrderException.class,
      expectedExceptionsMessageRegExp = ".*at least one item.*")
public void placeOrder_empty_throws() { service.placeOrder(emptyOrder); }

Flag legacy JUnit 4 @Test(expected=...) and bare try/catch/fail patterns as smells.

Mystery Guest — Common Java Patterns

Integration Test Markers

• File suffix: *IT.java (Failsafe convention), *IntegrationTest.java, *E2ETest.java

• Annotations: @SpringBootTest, @DataJpaTest, @Tag("integration"), @Category(IntegrationTests.class) (JUnit 4)

• TestNG: @Test(groups = {"integration"})

• Use of Testcontainers, embedded Kafka/Mongo, or @Sql scripts

Setup/Teardown

Tag/Trait Attributes (for test-tagging)

For JUnit 4, marker interfaces must exist (e.g., interface NegativeTests {}). Suggest creating them rather than dropping @Category references with no target.

For Maven Surefire, register groups in pom.xml:

<configuration>
    <groups>positive,critical-path</groups>
</configuration>

Language-specific calibration notes

• Argument-order trap (TestNG): Assert.assertEquals(actual, expected) reverses JUnit's order. Misordered comparisons produce backwards failure messages but still pass/fail correctly. Flag as smell when reviewing TestNG suites.

• JUnit 4 @Test(expected=...) loses precise exception location and accepts subclasses; recommend migrating to assertThrows.

• @SpringBootTest bootstraps the entire application — almost always an integration test.

• AssertJ chaining is a single assertion conceptually; do not count each chained .has... as a separate assertion for assertion-count metrics.

• Mockito verify(...) counts as a state/side-effect assertion when used to assert behavior — do not flag tests that only verify as assertion-free.

• Lombok @SneakyThrows in tests is acceptable; do not flag.

• Parameterized tests (@ParameterizedTest + @MethodSource / @ValueSource) are NOT duplicate tests; they are the consolidated form.