White Box Testing Given the following method in Java, which finds the maximum va

Question

White Box Testing

Given the following method in Java, which finds the maximum value in an array of integers.

public static int maximumValue(int[] a) {

   if (a != null && a.length > 0) {

     int max = a[0];

     for (int i = 1; i < a.length; i++) {

       if (a[i] > max) {

         max = a[i];

       }

     }

     return max;

   }

   return Integer.MIN_VALUE;

}

Design a test suite with the fewest number of test cases that satisfies the statement test criterion.

Design a test suite with the fewest number of test cases that satisfies the branch-condition test criterion.

Explanation / Answer

Create seperate Test Cases for every possible cases to Test the given method.

Since the class name is not provided, I assume the class where the maximumValue() method is
present as FindMax.java.

The possible scenarios are:
int[] all_equals = {0,0,0,0,0};         // TestCase 1 returns: 0
int[] all_positive = {1,2,3,4,5};    // TestCase 2 returns: 5
int[] all_negative = {-1,-2,-3,-4,-5}; // TestCase 3 returns: -1
int[] out_of_size = {1,2,3,4,5,6};     // TestCase 4 returns: Integer.Min_Value
int[] mixed = {-10,10,3,5,-6};         // TestCase 5 returns: 10
int[] empty = {};                     // TestCase 6 returns: Integer.Min_Value

I will show for 2 scenarios, you can extend to all the six scenarios.
-----------------------------------------------------------------------------------
For Scenario 1: Create file called TestJunit1.java with below code.

import org.junit.Test;
import org.junit.Ignore;
import static org.junit.Assert.assertEquals;

public class TestJunit1 {

int[] all_equals = {0,0,0,0,0};  
int retVal = 0;
FindMax getMax = new FindMax();

@Test
public void testEquals() {  
System.out.println("Inside testEquals()");
assertEquals(retVal, getMax.maximumValue(all_equals));   
}
}

-----------------------------------------------------------------------------------
For Scenario 2: Create file called TestJunit2.java with below code.

import org.junit.Test;
import org.junit.Ignore;
import static org.junit.Assert.assertEquals;

public class TestJunit2 {

int[] all_positive = {1,2,3,4,5};
int retVal = 5;
FindMax getMax = new FindMax();

@Test
public void testPositive() {  
System.out.println("Inside testPositive()");
assertEquals(retVal, getMax.maximumValue(all_positive));   
}
}
-----------------------------------------------------------------------------------
Similarly write seperate files for other scenarios as mentioned above.

Now to have the test suite, please create below files with the code as below.
-----------------------------------------------------------------------------------
Create a file TestSuite.java

import org.junit.runner.RunWith;
import org.junit.runners.Suite;

@RunWith(Suite.class)

@Suite.SuiteClasses({
TestJunit1.class,
TestJunit2.class
// Include other classes as you add them.
})

public class JunitTestSuite {   
}

-----------------------------------------------------------------------------------
Create TestRunner.java file

import org.junit.runner.JUnitCore;
import org.junit.runner.Result;
import org.junit.runner.notification.Failure;

public class TestRunner {
public static void main(String[] args) {
Result result = JUnitCore.runClasses(JunitTestSuite.class);

for (Failure failure : result.getFailures()) {
System.out.println(failure.toString());
}
      
System.out.println(result.wasSuccessful());
}
}
-----------------------------------------------------------------------------------

Compile all the classes as below:
$javac FindMax.java TestJunit1.java TestJunit2.java JunitTestSuite.java TestRunner.java

Now run the Test Runner, which will run the test case defined in the provided Test Case class.
$java TestRunner

OUTPUT:
Inside testPrintMessage()
true
Inside testPositive()
true

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