CSE 331, Spring 2011
Section 4 cheat sheet
JUnit, OO design patterns
JUnit 4
Method annotations:
tag description
@Test
@Test(timeout = time)
@Test(expected = exception.class)
Turns a public method into a JUnit test case.
Adding a timeout will cause the test case to fail
after time milliseconds. Adding an expected
exception will cause the test case to fail if
exception is not thrown.
@Before Method to run before every test case
@After Method to run after every test case
@BeforeClass Method to run once, before any test cases have
run
@AfterClass Method to run once, after all test cases have run
Assertion methods:
method description
assertTrue(test)fails if the Boolean test is false
assertFalse(test)fails if the Boolean test is true
assertEquals(expected, actual)fails if the values are not equal
assertSame(expected, actual)fails if the values are not the same (by ==)
assertNotSame(expected, actual)fails if the values are the same (by ==)
assertNull(value)fails if the given value is not null
assertNotNull(value)fails if the given value is null
fail() causes current test to immediately fail
Each method can also be passed a string to display if it fails, e.g.
assertEquals(“message”, expected, actual)
Unit testing tips:
•The entire goal is FAILURE ATOMICITY – the ability to know exactly what failed when a test case did not pass
•Tests should be self-contained and not care about each other
•You cannot test everything! Instead, think about:
oboundary cases,
oempty cases,
oerror cases
obehavior in combination (but not to excess)
•Each test case should test ONE THING
o10 small tests are better than 1 test 10x as large
oRule of thumb: 1 assert statement per test case
oTry to avoid complicated logic
•Torture tests are ok, but only in addition to simple tests
JUnit best practices:
•Use descriptive test names
•Add a default timeout to every test
•Use private methods to get rid of redundant test code
