Unit TestingBuilding Rock-Solid Software

Svetlin Nakov

Telerik Software Academyhttp://academy.telerik.com

Manager Technical Traininghttp://www.nakov.com

What is Unit Testing?

Unit Test – 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]

Unit Test – 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");}

Unit Testing – 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 Studio Team Test (VSTT)

NUnit, MbUnit, Gallio, etc.5

Unit Testing Frameworks &

JUnit

Unit Testing 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 Studio Team Test (VSTT) Developed by Microsoft, integrated

in VS

7

Unit Testing 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

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>

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

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)

JUnit – Assertions (2) Conditions

assertTrue(condition)

assertFalse(condition)

Forced test fail

fail()

Expecting exception

@Test(expected=IndexOutOfBoundsException.class)

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; }

}

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); }

}

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; }}

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 {

}

Eclipse and JUnit

Eclipse has built-in support for integration with JUnit

Can create, run and debug JUnit tests

Testing with JUnitLive Demo

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Unit Testing

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