JUnit – Parameterized Test

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

  1. Constructor
  2. 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

junit-parameterized-1

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

junit-parameterized-2
Note
TestNG is more flexible in the way of passing the parameters into unit tests, read this TestNG parameter test.

References

  1. Domain Name RegEx Example
  2. JUnit Parameterized JavaDoc
  3. TestNG Parameter Test
  4. Zohhak - JUnit parameterized made simple
  5. JUnit Wiki - Parameterized

About the Author

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mkyong
Founder of Mkyong.com, love Java and open source stuff. Follow him on Twitter, or befriend him on Facebook or Google Plus. If you like my tutorials, consider make a donation to these charities.

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Piotrek
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Piotrek

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(… 
}
mkyong
Guest
mkyong

Thanks, hope JUnit can implements some similar in future release.

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Miguel Ping
Guest
Miguel Ping

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
Guest
tobi

thanks very much.. this really helped me!

kapil
Guest
kapil

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.

mkyong
Guest
mkyong

Better split out the test case.

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Ramesh Kadali
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Ramesh Kadali
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;… Read more »
Dileep
Guest
Dileep

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() {
           ---------------------------------------
            --------------------------------
	}
Neel
Guest
Neel

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();
Manjunath
Guest
Manjunath

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)

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Binod Pant
Guest
Binod Pant
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… Read more »
Harry
Guest
Harry

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

micky
Guest
micky

not nice

mkyong
Guest
mkyong

Sad to heard that, May I know which area should be improve?