Building Rock-Solid Software Svetlin Nakov Telerik Software Academy Manager Technical Training

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]

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

 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

 JUnit  The first popular unit testing framework  Based on Java, written by  Based on Java, written by Kent Beck & Co.Kent Beck  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

 JUnit – the first unit testing framework   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:

 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 java org.junit.runner.JUnitCore

 Annotates a test case  Annotates methods called before/after each test  Annotates methods called one time before and after all test cases in the class  Ignores a test case 10

 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)

 Conditions  assertTrue(condition)  assertFalse(condition)  Forced test fail  fail()  Expecting exception ion.class)

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

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

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

 Suits are sets of JUnit test classes  We can define test suits with annotations: import org.junit.runner.RunWith; import org.junit.runners.Suite; Test2.class}) public class AllTests { }

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

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