Is there a Java alternative to Ploeh's AutoFixture for .Net?

Question

I am looking for a Java tool that would create anonymous variables (variables whose value I don't care about) in my tests, similar to AutoFixture in .Net. Here is a link to AutoFixture's readme, which has pretty good examples of what it does.

Here is a short example taken from the same readme:

[TestMethod]
public void IntroductoryTest()
{
    // Fixture setup
    Fixture fixture = new Fixture();

    int expectedNumber = fixture.CreateAnonymous<int>();
    MyClass sut = fixture.CreateAnonymous<MyClass>();
    // Exercise system
    int result = sut.Echo(expectedNumber);
    // Verify outcome
    Assert.AreEqual<int>(expectedNumber, result, "Echo");
    // Teardown
}

Is there such a tool in the Java world?

Edit:

I tried QuickCheck and while it managed to do something like what I was looking for:

import net.java.quickcheck.Generator;
import net.java.quickcheck.generator.PrimitiveGenerators;
import net.java.quickcheck.generator.support.ObjectGeneratorImpl;

public class Main {

interface Test{
     String getTestValue();
}

public static void main(String[] args) {
    Generator<String> stringGen = PrimitiveGenerators.strings(5, 100);
    Generator<Integer> intGen = PrimitiveGenerators.integers(5, 20);

    ObjectGeneratorImpl<Test> g = new ObjectGeneratorImpl<>(Test.class);
    g.on(g.getRecorder().getTestValue()).returns(stringGen);


    for (int i = 0; i < intGen.next(); i++) {
        System.out.println("value of testValue is: " + g.next().getTestValue());
    }
}

}

The tool seems to work only with interfaces. If I change Test to be a class and the method to a field, the generator throws an exception that only interfaces are supported.

I sincerely hope that there is something better, especially since the documentation is seriously lacking.

Answer 1

There is a Java implementation of QuickCheck, which has APIs for generating test data:

http://java.net/projects/quickcheck/pages/Home

I'm not too familiar with AutoFixture, and I suspect that QuickCheck is a slightly different kind of test framework, but maybe it is useful for solving your specific problem.

Answer 2

There's also JFixture which is available on github and published to maven central.

This is still under active development, and feature requests are being honoured.

Answer 3

Ivan,

I started a project focused on reimplementing core features of AutoFixture in java. AutoFixture has certainly a lot of features, so I need to prioritize which ones to implement first and which ones not to bother implementing at all. As the project is just started, I welcome testing, defect reports and feature requests.

Answer 4

I am using JFixture along Mockito.spy() for that ;)

Let's see an example how to do something that it would be trivial with AutoFixture and C#. The idea here is to generate random data in your object except for some specific methods that need to have specific values. It is interesting I didn't find that somewhere stated.. This technique eliminates the "Arrange" part of your unit tests to be a small number of lines and in addition focuses on what values need to be specific for this unit test to pass

public class SomeClass {
    public int id; //field I care
    public String name; // fields I don't care
    public String description; //fields I don't care

    public int getId(){
        return id;
    } 

    public void setId(int id){
        this.id = id;
    }

    public String getName(){
        return name;
    }

    public void setName(String name){
        this.name = name;
    }

    public String getDescription(){
        return description;
    }

    public void setDescirption(String description){
        this.description = description;
    }
}



public static void main(String args[]){
    JFixture fixture = new JFixture();
    fixture.customise().circularDependencyBehaviour().omitSpecimen(); //omit circular dependencies
    fixture.customise().noResolutionBehaviour().omitSpecimen(); // omit methods that cannot be resolved
    SomeClass entity = fixture.create(SomeClass.class);
    SomeClass mock = Mockito.spy(entity);
    Mockito.when(mock.getId()).thenReturn(3213);

    System.out.println(mock.getId()); // always 3213
    System.out.println(mock.getName()); // random
    System.out.println(mock.getDescription()); //random
}

This prints:

3213
name9a800265-d8ef-4be9-bd45-f0b62f791d9c
descriptiona9f9245f-eba1-4805-89e3-308ef69e7091

Answer 5

Try object factory. It is open sourced on github. It can create random Java objects in just a single line of code. And it is highly configurable.

Example:

ObjectFactory rof = new ReflectionObjectFactory();

String str = rof.create(String.class);
Customer cus = rof.create(Customer.class);

It is also available in Maven Central Repository.

Answer 6

ObjectGenerator is more of an experimental feature:

ObjectGenerator<Test> objects = PrimitiveGenerators.objects(Test.class);
objects.on(objects.getRecorder().getTestValue()).returns(PrimitiveGenerators.strings());

Test next = objects.next();
System.out.println(next.getTestValue());

I'd prefer a simple Generator implementation:

class TestGenerator implements Generator<Test>{
    Generator<String> values = PrimitiveGenerators.strings();
    @Override public Test next() {
        return new TestImpl(values.next());
    }   
}

Answer 7

Yet Another QuickCheck for Java is another tool you may probably take a look.

It is very integrated with JUnit (it supports tests with parameters, annotations to configure the generated objects and so on).

It has a lot of generators (all of quickcheck, and some specific to OOP, such as interfaces, abstract classes and singleton generators), and you can define your own ones. There is also a constructor-based generator.

Currently is in alpha status, but if you take a look to the downloads page you'll see a basic documentation.