For each property parameter, junit-quickcheck uses a unique value as a seed for the source of randomness used to generate the parameter’s values. To fix the seed value for a property parameter, use the seed attribute of the @When annotation.

    public class SameValues {
        @Property public void holds(@When(seed = -1L) int i) {
            // ...

You may want to fix the seed when a property fails, so that you can test the property over and over again with the same set of generated values that caused the failure.

junit-quickcheck reports the seed used for a given property parameter in the message of the AssertionError raised when a property fails.

java.lang.AssertionError: Property named 'myProperty' failed:
With arguments: [10]
Original failure message:
Expected: a value less than <1>
     but: <10> was greater than <1>
First arguments found to also provoke a failure: [753701363]
Seeds for reproduction: [-6700838609453830748]