Unit testing involves writing small pieces of code called unit tests to test specific areas of functionality in code. A unit test verifies that a particular function or method works as expected. Frameworks like JUnit provide annotations and assertions to help write and organize unit tests. Unit tests should be written by developers and stored alongside the code being tested to ensure code quality.

1. UnitTesting
Building Rock-Solid Software
Svetlin Nakov
Telerik Software Academy
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ManagerTechnicalTraining
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2. What is UnitTesting?

3. UnitTest – Definition
A unit test is a piece of code written by
a developer that exercises a very small,
specific area of functionality of the code
being tested.
“Program testing can be used to show the
presence of bugs, but never to show their
absence!”
Edsger Dijkstra, [1972]

4. UnitTest – Example
int sum(int[] array) {
int sum = 0;
for (int i=0; i<array.length; i++)
sum += array[i];
return sum;
}
void testSum() {
if (sum(new int[]{1,2}) != 3)
throw new TestFailedException("1+2 != 3");
if (sum(new int[]{-2}) != -2)
throw new TestFailedException("-2 != -2");
if (sum(new int[]{}) != 0)
throw new TestFailedException("0 != 0");
}

5. UnitTesting – Some Facts
 Tests are pieces of code (small programs)
 In most cases unit tests are written by
developers, not by QA engineers
 Unit tests are released into the code repository
(TFS / SVN / Git) along with the code they test
 Unit testing framework is needed
 Visual StudioTeamTest (VSTT)
 NUnit, MbUnit, Gallio, etc.
5

6. UnitTesting
Frameworks & JUnit

7. UnitTesting Frameworks
 JUnit
 The first popular unit testing framework
 Based on Java, written by Kent Beck & Co.
 Similar frameworks have been developed for a
broad range of computer languages
 NUnit – for C# and all .NET languages
 cppUnit, jsUnit, PhpUnit, PerlUnit, ...
 Visual StudioTeamTest (VSTT)
 Developed by Microsoft, integrated inVS
7

8. UnitTesting Frameworks
 JUnit – the first unit testing framework
 www.junit.org
 Based on Java
 Developed by Erich Gamma and Kent Beck
 Unit testing frameworks have been developed for a
broad range of computer languages
 NUnit – for C#,VB.NET and .NET languages
 cppUnit, DUnit, jsUnit, PhpUnit, PerlUnit, ...
 List of xUnit frameworks can be found at:
http://www.testingfaqs.org/t-unit.html

9. JUnit – Features
 Test code is annotated using Java 5
annotations
 Test code contains assertions
 Tests are grouped in test fixtures and test
suites
 Several execution interfaces
 Eclipse integrated plug-in
 Console interface:
java org.junit.runner.JUnitCore <test-class>

10. JUnit – Annotations
 @Test
 Annotates a test case method
 @Before, @After
 Annotates methods called before/after each test
case
 @BeforeClass, @AfterClass
 Annotates methods called one time before and
after all test cases in the class
 @Ignore
 Ignores a test case
10

11. JUnit – Assertions
 Using org.junit.Assert class
 Assertions check a condition and throw exception if
the condition is not satisfied
 Comparing values
 assertEquals ([message], expected value,
calculated value)
 Comparing objects
 assertNull([message], object)
 assertNotNull([message], object)
 assertSame ([message], expected obj,
calculated obj)

12. JUnit – Assertions (2)
 Conditions
 assertTrue(condition)
 assertFalse(condition)
 Forced test fail
 fail()
 Expecting exception
 @Test(expected=IndexOutOfBoundsExcept
ion.class)

13.  Java class that needs unit testing:
JUnit – Example
public class Sumator {
public int sum(int a, int b) {
int sum = a + b;
return sum;
}
public int sum(int... nums) {
int sum = 0;
for (int i = 0; i < nums; i++)
sum += nums[i];
return sum;
}
}

14.  JUnit based test class (fixture):
JUnit – Example
import org.junit.Test;
import static org.junit.Assert.*;
public class SumatorTest {
@Test
public void testSum() {
Sumator sumator = new Sumator();
int sum = sumator.sum(new int[] {2,3,4});
assertEquals(sum, 9);
}
}

15.  JUnit text fixture with setup and cleanup:
JUnit – Example
public class SumatorTest {
private Sumator sumator;
@Before public void setUpTestCase() {
this.sumator = new Sumator();
}
@Test public void testSum() {
int sum = sumator.sum(2, 3);
assertEquals(sum, 5);
}
@After public void cleanUpTestCase() {
this.sumator = null;
}
}

16. Test Suites
 Suits are sets of JUnit test classes
 We can define test suits with annotations:
import org.junit.runner.RunWith;
import org.junit.runners.Suite;
import org.junit.runners.Suite.SuiteClasses;
@RunWith(value=Suite.class)
@SuiteClasses(value={Test1.class, Test2.class})
public class AllTests {
}

17. Eclipse and JUnit
 Eclipse has
built-in
support for
integration
with JUnit
 Can create,
run and
debug JUnit
tests

18. Testing with JUnit
Live Demo

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