Tutorial 7. Adding A New Random Generator

Why is this necessary?

On occasion, you will have a class or need to randomly generate a class for testing but its construction requires special parameters. For example, if you have an Age class representing a person's age, you may have a single constructor that takes a positive int.

OpenPojo's random default constructor will send a random int without regards for this constraint, which may throw an error. The proper work around for this is to register a RandomGenerator for Age.

Example

1. Create a Random Generator for your Age class.

public class AgeRandomGenerator implements RandomGenerator {
  private static final Class<?>[] TYPES = = new Class<?>[] { Age.class };
  private static final Random RANDOM = new Random(System.currentTimeMillis());

  // Set your upper bound for how old someone can be.
  private static final int MAX_AGE = 130;

  public Object doGenerate(Class<?> type) {
    return new Age(RANDOM.nextInt(MAX_AGE);
  }

  public Collection<Class<?>> getTypes() {
    return Arrays.asList(TYPES);
  }

}

2. Register your new RandomGenerator as part of your test setup.

public class SomeTest {
  @BeforeClass
  public static void onlyOnce() {
    RandomFactory.addRandomGenerator(new AgeRandomGenerator());
  }

  // The rest of your test code goes here.
  // [...]

}