unit test Updated June 10, 2016 by mkyong 16 comments

JUnit – Parameterized Test

In JUnit, you can pass the parameters into the unit test method via the following methods :

Constructor
Fields injection via @Parameter

P.S Tested with JUnit 4.12

1. MatchUtils – Test with multiple parameters

A simple add operation.

MathUtils.java


package com.mkyong.examples;

public class MathUtils {

    public static int add(int a, int b) {
        return a + b;
    }

}

1.2 MatchUtils – Parameterized via Constructor

The parameters are passed into the test method via constructor.

ParameterizedTest.java


package com.mkyong;

import com.mkyong.examples.MathUtils;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;

import java.util.Arrays;
import java.util.Collection;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

@RunWith(value = Parameterized.class)
public class ParameterizedTest {

    private int numberA;
    private int numberB;
    private int expected;

    // Inject via constructor
    // for {8, 2, 10}, numberA = 8, numberB = 2, expected = 10
    public ParameterizedTest(int numberA, int numberB, int expected) {
        this.numberA = numberA;
        this.numberB = numberB;
        this.expected = expected;
    }

	// name attribute is optional, provide an unique name for test
	// multiple parameters, uses Collection<Object[]>
    @Parameters(name = "{index}: testAdd({0}+{1}) = {2}")
    public static Collection<Object[]> data() {
        return Arrays.asList(new Object[][]{
                {1, 1, 2},
                {2, 2, 4},
                {8, 2, 10},
                {4, 5, 9},
                {5, 5, 10}
        });
    }

    @Test
    public void test_addTwoNumbes() {
        assertThat(MathUtils.add(numberA, numberB), is(expected));
    }

}

1.3 MatchUtils – Parameterized via Field Injection

The parameters are passed into the test method via field injection.

ParameterizedTest.java


package com.mkyong;

import com.mkyong.examples.MathUtils;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;
import org.junit.runners.Parameterized.Parameter;

import java.util.Arrays;
import java.util.Collection;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

@RunWith(value = Parameterized.class)
public class ParameterizedTest {

    //default value = 0
    @Parameter(value = 0)
    public int numberA;

    @Parameter(value = 1)
    public int numberB;

    @Parameter(value = 2)
    public int expected;

    @Parameters(name = "{index}: testAdd({0}+{1}) = {2}")
    public static Collection<Object[]> data() {
        return Arrays.asList(new Object[][]{
                {1, 1, 2},
                {2, 2, 4},
                {8, 2, 10},
                {4, 5, 9},
                {5, 5, 10}
        });
    }

    @Test
    public void test_addTwoNumbes() {
        assertThat(MathUtils.add(numberA, numberB), is(expected));
    }

}

Note
For @Parameters, the “name” attribute is optional, it helps you to identify individual test cases by providing a unique name.

What is {0}, {1} and {2}?
If the parameter is “{ 3, 4, 7 }”, then {0} = 3, {1} = 4, {2} = 7.

Output

2. DomainUtils – Test with single parameter

Another simple class, validate a domain name.

DomainUtils.java


package com.mkyong.examples;

import java.util.regex.Pattern;

public class DomainUtils {

    private static final String DOMAIN_NAME_PATTERN = "^((?!-)[A-Za-z0-9-]{1,63}(?<!-)\\.)+[A-Za-z]{2,6}$";
    private static Pattern pDomainName = Pattern.compile(DOMAIN_NAME_PATTERN);

    public static boolean isValid(String domainName) {
        return pDomainName.matcher(domainName).find();
    }

}

2.1 DomainUtils Parameterized Test

The parameters are passed into the test method via field injection.

ParameterizedTest.java


package com.mkyong;

import com.mkyong.examples.DomainUtils;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameter;
import org.junit.runners.Parameterized.Parameters;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

@RunWith(value = Parameterized.class)
public class Parameterized2Test {

    //default value = 0
    @Parameter
    public String domainName;

	//Single parameter, use Object[]
    @Parameters(name = "{index}: testDomain - {0}")
    public static Object[] data() {
        return new Object[]{
                "google.com",
                "mkyong.com",
                "twitter.com"
        };
    }

    @Test
    public void test_valid_domain() {
        assertThat(DomainUtils.isValid(domainName), is(true));
    }

}

Output

Note
TestNG is more flexible in the way of passing the parameters into unit tests, read this TestNG parameter test.

References

Written by mkyong

Software Engineer • Writer • Dad

20+ years hands-on, writing about Java, Spring, and AI. Every code example here is tested.

All posts by mkyong

16 comments on “JUnit – Parameterized Test”

Nayanb
January 21, 2020 at 3:10 pm

please change the title heading from MatchUtils to MathUtils

Reply
micky
December 11, 2013 at 3:04 pm

not nice

Reply
1. mkyong
  June 10, 2016 at 11:49 am
  
  Sad to heard that, May I know which area should be improve?
  
  Reply
Piotrek
December 7, 2012 at 4:14 pm
there is a simpler way. check zohhak.googlecode.com it lets you write:
```
@TestWith({ 
   “2,  true”, 
   “6,  false”,
   “19, true” 
})
public void testPrimeNumberValidator(int number, boolean isPrime) { 
   assertThat(… 
}
```
Reply
1. mkyong
  June 10, 2016 at 11:49 am
  
  Thanks, hope JUnit can implements some similar in future release.
  
  Reply

Miguel Ping

September 25, 2012 at 7:06 pm

Nice post. BTW, it seems that is supporting any data time:

	@Parameters
	public static List<Object[]> data()
	{
		return Arrays.asList(new Object[][] { { DesiredCapabilities.chrome() }, { DesiredCapabilities.internetExplorer() } });
	}

tobi
July 17, 2012 at 4:52 pm

thanks very much.. this really helped me!

Reply
kapil
July 9, 2012 at 5:34 pm

Hi ,

I want to know that how we can implement different assertion for each parameter in same test case.
As the collection of object is passed to constructor of Class. for every test run i want to have different assertion but that is not possible in current example.
Thanks in advance.

Reply
1. mkyong
  June 10, 2016 at 11:52 am
  
  Better split out the test case.
  
  Reply

Ramesh Kadali

May 8, 2012 at 4:11 am

Hi,
Could you please help me out regarding below issue:
First Test case failure is carried to other consecutive tests when I used Parameterized tests. How can I skip this error:

Below is the snippet of the code:

package com.ncr.travel.airline.tests.myCopy;

import static org.junit.Assert.*;

import java.util.Arrays;
import java.util.List;

import org.junit.AfterClass;
import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ErrorCollector;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;

@RunWith(Parameterized.class)
public class ServerBuilderTest {
       @Parameters
       public static List<Object[]> data() {
    	   Object[][] lc = new Object[3][1];
    		lc[0][0]=0;
    		lc[1][0]=1;
    		lc[2][0]=0;
               return Arrays.asList(lc);
       }

       private int fInput;
       private int fExpected;

       public ServerBuilderTest(int input) {
           super();    
    	   fInput= input;
       }
       @Rule
   	public static ErrorCollector errCollect = new ErrorCollector();
   	@BeforeClass
	public static void setUp() throws Exception {
   		System.out.println("test");
   	}
	@AfterClass
	public static void tearDown() throws Exception {
		System.out.println("After Test");
	}
       
       @Test
       public void test() {
    	   try{
               Assert.assertEquals(0, fInput);
    	   }
    	   catch (Throwable t) {
    		   System.out.println(t);
    		   errCollect.addError(t);
    	   }

               
       }
}

Dileep
July 17, 2012 at 11:24 pm
Just remove the try and catch construct in test method
issue found in the above code is :

1) junit4 doesn’t have (Not worked for me)
```
@Rule
public static ErrorCollector errCollect = new ErrorCollector();
```
2) private int fExpected;
an unnecessary variable
3) Exception handling in the test case is not appreciated …
good to use like below
```
@Test(expected = XXXXXXException.class)
	public void XXXXX() {
           ---------------------------------------
            --------------------------------
	}
```
Reply
Neel
July 25, 2012 at 8:57 am
Hello Ramesh,
I think the issue is that you have ‘static’ declared in your @Rule.
create error collector instance without the ‘static’ keyword and it should work fine in Junit 4.
```
@Rule
public ErrorCollector errColl = new ErrorCollector();
```
Reply

Manjunath
February 18, 2012 at 8:10 pm

Hi ,

Am new to Junit Testing and getting Initialization error while running Test class . pls help in resolving it , Thanks in advance

code :

package com.source;

import java.util.Arrays;
import java.util.Collection;

import static org.junit.Assert.*;

import org.junit.After;
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;

@RunWith(Parameterized.class)
public class ParameterizedAddclassTest {
public int a[];
public int expected;

ParameterizedAddclassTest(int inputparameters[],int expected)
{
this.a=inputparameters;
this.expected=expected;
}
@Parameterized.Parameters
public static Collection parameterPassing()
{
return Arrays.asList(new Object[][]{ {new int[]{5,2,3},10} ,
{new int[] {5,10,15},30}
});
}

@Test
public void TestaddClass()
{
Addclass add =new Addclass();
int actual=add.addClass(a);
System.out.println(actual);
assertEquals(actual,expected);
}

}

error :
java.lang.AssertionError: expected: but was:
at org.junit.Assert.fail(Assert.java:58)
at org.junit.Assert.failNotEquals(Assert.java:259)
at org.junit.Assert.assertEquals(Assert.java:80)
at org.junit.Assert.assertEquals(Assert.java:88)
at org.junit.runners.Parameterized$TestClassRunnerForParameters.getOnlyConstructor(Parameterized.java:100)
at org.junit.runners.Parameterized$TestClassRunnerForParameters.(Parameterized.java:80)
at org.junit.runners.Parameterized$RunAllParameterMethods.(Parameterized.java:115)
at org.junit.runners.Parameterized.(Parameterized.java:140)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:27)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.(JUnit4TestReference.java:29)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestClassReference.(JUnit4TestClassReference.java:25)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createTest(JUnit4TestLoader.java:40)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.loadTests(JUnit4TestLoader.java:30)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:452)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

Reply
Binod Pant
September 11, 2010 at 3:14 am

I am trying to subclass a Junit class to be used a ‘harness’ for parameterizing tests. I Want to subsclass a class that looks like

@RunWith(Parameterized.class)
public class A {
@Parameters
public Collection data() {
return overrideableMethod();
}

}

Subclass

public class B extends A {
@Override
public Object[] overrideableMethod() {
// change list of parmeters
}
@Test a() {
}
}

However, this seems not to be possible due to Java treating the @Parameters annotation.

My main objective is to simplify subclasses so that they don’t have to use the @Parameters and @RunWith annotations, and automatically get benefit of some standard parameters built into the base class

Any tips / ideas?

Reply
Harry
October 19, 2009 at 9:02 pm

How do you make it jdk 1.5 (or above) compliance? I’m getting: The expression of type List needs unchecked conversion to conform to Collection

Reply
1. mkyong Author
  October 21, 2009 at 3:17 pm
  
  I’m using jdk1.6, has no warning at the above code.
  
  May be you can explicit convert the List to collection by using the following code,
  @Parameters
  public static Collection data() {
  Object[][] data = new Object[][] { { 1 }, { 2 }, { 3 }, { 4 } };
  return (Collection) Arrays.asList(data);
  }
  
  Did you use tTestNG before? Personally i more prefer to use TestNG as my unit test framework.
  
  https://mkyong.com/unittest/junit-4-vs-testng-comparison/
  
  Reply

JUnit – Parameterized Test

1. MatchUtils – Test with multiple parameters

1.2 MatchUtils – Parameterized via Constructor

1.3 MatchUtils – Parameterized via Field Injection

2. DomainUtils – Test with single parameter

2.1 DomainUtils Parameterized Test

References

16 comments on “JUnit – Parameterized Test”

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