JUnit Testing with Intellij IDE

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This is Intellij IDE JUnit Testing tutorial. You can refer to (Java Unit Testing with JUnit ) for original.

For this unit testing, I have created new project, no libraries, no template.

1. Create new directory "test", right click on project > add > directory.
   
2. Mark the directory as test sources root.
   
3. Create Calculator class, the class is created as , right click on project > add > java class.
   paste the code
   
   

   public class Calculator{
   
       // default values
       double p = 0.0;
       double t = 0.0;
       double r = 0.0;
   
       // constructor that updates the values
       public Calculator(double p, double t, double r){
           this.p = p;
           this.t = t;
           this.r = r;
       }
   
       // method that calculates the interest
       public double calculateInterest(){
           return p*t*r / 100;
       }
   }
   

4. Create test class for Calculator, press alt & enter on class name > create test.
   
   
   Configure JUnit like as this
   
   Fix and download library
   
   And the newly created testClass (CalculatorTest) will look like this 
   

   import org.junit.After;
   import org.junit.Before;
   import org.junit.Test;
   
   import static org.junit.Assert.*;
   
   public class CalculatorTest {
   
       Calculator calculator = null;
   
       // values for your test case
       double p = 10000.0;
       double t = 1.0;
       double r = 10.0;
   
       @Before
       public void setUp() throws Exception {
           calculator = new Calculator(p, t, r);
       }
   
       @After
       public void tearDown() throws Exception {
       }
   
       @Test
       public void calculateInterest() {
           assertEquals(1000.0, calculator.calculateInterest(), 0.0);
       }
   }
   

5. Create a TestRunner class inside test directory. This will be our entry point to perform all test, paste.
   
   

   import org.junit.runner.JUnitCore;
   import org.junit.runner.Result;
   import org.junit.runner.notification.Failure;
   
   public class TestRunner{
   
       public static void main(String[] str){
   
           // Run test classes and grab result
           Result result = JUnitCore.runClasses(CalculatorTest.class);
   
           // Test result
           System.out.println(result.wasSuccessful());
   
           // print the failure message if failure
           for(Failure failure : result.getFailures()){
               // print string
               System.out.println(failure.toString());
           }
   
       }
   }
   

6. Yey, test success.
   

References:

1. https://www.jetbrains.com/help/idea/configuring-testing-libraries.html