07-2-B-Testing-Coverage.adoc

Code Coverage using EclEmma

This tutorial covers the basics of EclEmma and retrieves code coverage metrics using it.

Preliminary

1. Install EclEmma as a plugin in your Eclipse IDE from here.

Creating a Gradle Project

Note	We will create a Gradle project from scratch and be testing a simple method returnAverage(int[], int, int, int) .

1. Create a new Gradle project in Eclipse by clicking on File > New > Other
   

2. Under Gradle, choose Gradle Project
   

3. Click on Next, then name your project tutorial7, click on Finish
   
   

   Note	The project may take some time to be created.

4. Create a new package instead of the default ones for both the source and test folders (e.g ca.mcgill.ecse321.tutorial7) and move the default generated classes (Library and LibraryTest) to this package.
   

5. Change the code in the Library class

   package ca.mcgill.ecse321.tutorial7;
   
   public class Library {
   
   	public static double returnAverage(int value[], int arraySize, int MIN, int MAX) {
   		int index, ti, tv, sum;
   		double average;
   		index = 0;
   		ti = 0;
   		tv = 0;
   		sum = 0;
   		while (ti < arraySize && value[index] != -999) {
   			ti++;
   			if (value[index] >= MIN && value[index] <= MAX) {
   				tv++;
   				sum += value[index];
   			}
   			index++;
   		}
   		if (tv > 0)
   			average = (double) sum / tv;
   		else
   			average = (double) -999;
   		return average;
   	}
   }

6. Change the code in the LibraryTest class

   package ca.mcgill.ecse321.tutorial7;
   
   import static org.junit.Assert.assertEquals;
   
   import org.junit.Test;
   
   public class LibraryTest {
   
   	@Test
   	public void allBranchCoverageMinimumTestCaseForReturnAverageTest1() {
   		int[] value = {5, 25, 15, -999};
   		int AS = 4;
   		int min = 10;
   		int max = 20;
   		double average = Library.returnAverage(value, AS, min, max);
   		assertEquals(15, average, 0.1);
   	}
   
   	@Test
   	public void allBranchCoverageMinimumTestCaseForReturnAverageTest2() {
   		int[] value = {};
   		int AS = 0;
   		int min = 10;
   		int max = 20;
   		double average = Library.returnAverage(value, AS, min, max);
   		assertEquals(-999.0, average, 0.1);
   	}
   }

Retrieving Test Coverage Metrics

Note	We can straightforwardly manage code coverage using JaCoCo inside Eclipse with no configuration if we are using EclEmma Eclipse plugin.

1. Run the Test in coverage mode using Eclemma. Click on LibraryTest, Coverage As, 1 JUnit Test
   

2. Verify that we have 100% branch coverage.