JUnit

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JUnit

• SWE 619
• Spring 2008

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What is JUnit?

• Open source Java testing framework used to write
  and run repeatable automated tests
• JUnit features include
• Assertions for testing expected results
• Test fixtures for sharing common test data
• Test suites for easily organizing and running
  tests
• Graphical and textual test runners

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Test Scenarios with JUnit

• Used to test
• A whole object
• Part of an object - a method or some interacting
  methods
• Interaction between several objects
• A test case represents one scenario
• A tester class contains more than one scenario
• Each senario is written into one test method

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Writing Tests for JUnit

• Need to use the methods of the junit.framework.ass
  ert class
• javadoc gives a complete description of its
  capabilities
• Each of these methods checks some condition and
  reports back to the test runner whether the test
  failed or succeeded.
• The test runner uses the result to update the
  display. All of the methods return void (i.e.
  they are procedures)

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Writing Tests for JUnit (contd)

• A few representative methods of
  junit.framework.assert
• assertTrue(boolean)
• assertTrue(String, boolean)
• assertEquals(Object, Object)
• assertNull(Object)
• fail(String)

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Sample Assertions (contd)

• static void assertEquals(boolean expected,
  boolean actual)           Asserts that two
  booleans are equal.
• static void assertEquals(byte expected,
  byte actual)           Asserts that two bytes
  are equal.
• static void assertEquals(char expected,
  char actual)           Asserts that two chars
  are equal.
• static void assertEquals(double expected,
  double actual, double delta)           Asserts
  that two doubles are equal concerning a delta.
• static void assertEquals(float expected,
  float actual, float delta)           Asserts
  that two floats are equal concerning a delta.
• static void assertEquals(int expected,
  int actual)           Asserts that two ints are
  equal.
• For a complete list, see
• http//junit.sourceforge.net/javadoc/junit/framewo
  rk/Assert.html

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How to write test case

• Two different ways for junit versions 3.X and
  4.x.
• In Junit 3.X
• 1) import junit.framework.2) extend TestCase.
• 3) name the test methods with a prefix of test
• 4) validate conditions using one of the several
  assert methods

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How to write test case (contd)

• In Junit 4.0 and later
• Do not extend from Junit.framework.TestCase
• Do not prefix the test method wit test
• Use one of the assert methods
• Run the test using JUnit4TestAdapter

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Simple Example

• public class Math         static public int
  add(int a, int b)                    return a
  b        

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Example JUnit test case

• import junit.framework.
• public class TestMath extends TestCase
•   public void testAdd()         int num1 3
          int num2 2         int total 5  
        int sum 0         sum Math.add(num1,
  num2)         assertEquals(sum, total)    

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Testing the Stack class

• public class Stack
• public String toString()
• // EFFECTS Returns the String
  representation of this Stack from the
• // top to the bottom.
• StringBuffer buf new
  StringBuffer("")
• for (int i size-1 i gt 0 i--)
  
• if (i lt (size-1))
• buf.append(", ")
• buf.append(elementsi.toS
  tring())
• buf.append("")
• return buf.toString()
• public boolean repOk()
• if (elements null) return
  false
• if (size ! elements.length)
  return false
• for (int i 0 i lt size i)

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TestCases with JUnit 4.X for Stack

• Necessary classes to be imported
• import org.junit.After
• import org.junit.Before
• import org.junit.Test
• import static org.junit.Assert.assertEquals
• import junit.framework.JUnit4TestAdapter

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TestCases with JUnit (Contd)

public class StackTest private Stack
stack / setUp method using
_at_Before annotation. Method can be
named anything. / _at_Before public
void runBeforeEachTest() stack
new Stack()
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Test case with JUnit (contd)

• _at_Test public void testRepOk()
• boolean result stack.repOk()
• assertEquals(true, result)
• stack stack.push(new
  Integer(1))
• result stack.repOk()
• assertEquals(true, result)
• stack stack.pop()
• result stack.repOk()
• assertEquals(true, result)
• stack stack.push(new
  Integer(1))
• stack.top()
• result stack.repOk()
• assertEquals(true, result)

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Test case with JUnit (contd)

• _at_Test public void testToString()
• stack stack.push(new
  Integer(1))
• stack stack.push(new
  Integer(2))
• assertEquals("2, 1",
  stack.toString())
• _at_After public void runAfterEachTest()
• stack null
• public static junit.framework.Test
  suite()
• return new JUnit4TestAdapter(StackT
  est.class)

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How to Run Tests

• JUnit provides test drivers
• Character-based test driver runs from the command
  line
• GUI-based test driver-junit.swingui.TestRunner
• allows to specify the test class to run,
• "Run" button
• examines the chosen class and finds all methods
  whose names begin with "test."
• If a test fails, Junit gives the location of the
  failure and any exceptions that were thrown

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JUnit Installation in Eclipse

• In Eclipse, select Help-gtSoftware Updates-gtFind
  and Install
• Choose 'Search For New Features to Install' and
  select 'Next'
• Select 'New Remote Site'
• Enter a name for this server JUnit Factory
• Enter (or copy/paste) this url
  http//www.junitfactory.com/update/
• Install all plug-ins in the 'JUnit Factory'
  category and restart Eclipse

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Generating Tests in Eclipse

• Select a Java class in Eclipse and click the
  Generate Tests ( )button
• When the JUnit Factory view says your test is
  done, click the link in the Result column to open
  it
• Select the test and choose Run-gtRun As-gtAgitar
  JUnit Test from the main menu

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Eclipse JUnit Plugin

• See tutorial
• http//open.ncsu.edu/se/tutorials/junit/
• http//www.laliluna.de/eclipse-junit-testing-tutor
  ial.html