Lecture Notes in Computer Science 3472

502 Zhen Ru Dai
TestResult
TestCase
run(TestResult)
runTest()
setUp()
tearDown()
fName
runTest()
Test
run(TestResult)
Fig. 17.2. JUnit Classes
TestSuite
run(TestResult)
addTest(Test)
unexpected way. If one does not have an automated test, broken subsystems
may not be tested. For these reasons, unit-level tests assure that the code a
developer has written will be tested automatically, and thus give confidence in
the code.
JUnit is a framework for writing unit tests. This section introduces the JUnit
framework and provides the mapping from the U2TP concepts to JUnit concepts.
Fundamentals of JUnit JUnit is written by Erich Gamma and Kent Beck. It is an
open source framework for automated unit tests. JUnit tests are based on Java.
Thus, its execution code is also Java for which there exist various compilers.
By means of the JUnit framework, software developers can derive tests from
classes of the JUnit Framework and combine them into a test suite. A unit test
checks a single unit of the implementation code, e.g. a method or a class. Unit
tests are applied in a test driven design. The tests are developed in parallel to
code implementation. In the former, tests are even written before the codes are
implemented. The software developer writes the test routines for every piece of
code so that the test can be re-run every time the code is changed. For eXtreme
Programming [XP], where code integration and code testing are required permanently,
unit tests are obligatory. Because of its simplicity, JUnit has become
very popular in the XP domain. JUnit is integrated in many toolkits, e.g. Eclipse
[ECla] or JBuilder [JBu].
In JUnit, a test case is the basic abstraction. A test case can be run in order
to check if the test passes. It contains the test methods setUp() and tearDown(),
a main() method which runs the test case and an optional suite() method which
groups test methods in a test suite (Figure 17.2). Usually, every class that is
written should have a test case. A JUnit test suite is structured in a hierarchical
way and is composed of test cases or other test suites. A test fixture allows test