PMD Coding practices - JUnit

JUnit - rules provided by PMD

JUnitStaticSuite

The suite() method in a JUnit test needs to be both public and static.

JUnitSpelling

Some JUnit framework methods are easy to misspell.

JUnitAssertionsShouldIncludeMessage

JUnit assertions should include an informative message - i.e., use the three-argument version of assertEquals(), not the two-argument version.

JUnitTestsShouldIncludeAssert

JUnit tests should include at least one assertion.

This makes the tests more robust, and using assert with messages provide the developer a clearer idea of what the test does.

TestClassWithoutTestCases

Test classes end with the suffix Test.

Having a non-test class with that name is not a good practice, since most people will assume it is a test case.

Test classes have test methods named testXXX.

UnnecessaryBooleanAssertion

A JUnit test assertion with a boolean literal is unnecessary since it always will evaluate to the same thing.

Consider using flow control (in case of assertTrue(false) or similar) or simply removing statements like assertTrue(true) andassertFalse(false).

If you just want a test to halt after findingan error, use the fail() method and provide an indication message of why it did.

UseAssertEqualsInsteadOfAssertTrue

This rule detects JUnit assertions in object equality.

These assertions should be made by more specific methods, like assertEquals.

UseAssertSameInsteadOfAssertTrue

This rule detects JUnit assertions in object references equality.

These assertions should be made by more specific methods, like assertSame, assertNotSame.

UseAssertNullInsteadOfAssertTrue

This rule detects JUnit assertions in object references equality.

These assertions should be made by more specific methods, like assertNull, assertNotNull.

SimplifyBooleanAssertion

Avoid negation in an assertTrue or assertFalse test.

For example, rephrase : assertTrue(!expr);

as : assertFalse(expr);

JUnitTestContainsTooManyAsserts

JUnit tests should not contain too many asserts. Many asserts are indicative of a complex test, for which it is harder to verify correctness.

Consider breaking the test scenario into multiple, shorter test scenarios.

Customize the maximum number of assertions used by this Rule to suit your needs.

UseAssertTrueInsteadOfAssertEquals

When asserting a value is the same as a boolean literal, use assertTrue/assertFalse, instead of assertEquals.

Migration (JUnit)

JUnit4TestShouldUseBeforeAnnotation

In JUnit 3, the setUp method was used to set up all data entities required in running tests.

JUnit 4 skips the setUp method and executes all methods annotated with @Before before all tests

JUnit4TestShouldUseAfterAnnotation

In JUnit 3, the tearDown method was used to clean up all data entities required in running tests.

JUnit 4 skips the tearDown method and executes all methods annotated with @After after running each test

JUnit4TestShouldUseTestAnnotation

In JUnit 3, the framework executed all methods which started with the word test as a unit test.

In JUnit 4, only methods annotated with the @Test annotation are executed.

JUnit4SuitesShouldUseSuiteAnnotation

In JUnit 3, test suites are indicated by the suite() method.

In JUnit 4, suites are indicated through the @RunWith(Suite.class) annotation.

JUnitUseExpected

In JUnit4, use the @Test(expected) annotation to denote tests that should throw exceptions.