Random Utils Seeding Extension

RandomUtilsSeedingExtension is JUnit Jupiter extension that allows better control of RandomUtils’ random see in unit test environments.

Creating the extension

Like with any extension, the only thing you need to do in order to incorporate it in your test class is to add an @ExtendWith annotation.

@ExtendWith(RandomUtilsSeedingExtension.class)
public class MyTest{
    // Code

Logging the Random Seed

Now that you have the RandomUtilsSeedingRule defined, your test will automagically log the random seed it uses, e.g.:

11:02:24,643 INFO  [RandomUtilsSeedingRule] Property "test.random.seed" was not set, using System.currentTimeMillis() as a seed.
11:02:24,644 INFO  [RandomUtilsSeedingRule] Running test with random seed: 1337155344644

Note that this is done using oVirt’s standard LogFactory and Log, so make sure you configure the logging in your project.

Injecting a Random Seed

Once you have a failed test due to a specific random input, you would probably want to reproduce it. This can be done by specifying the environment variable test.random.seed.

You can make sure the injection worked properly by examining the log. If, for example, you set test.random.seed=123, your output should look like this:

11:11:53,159 INFO  [RandomUtilsSeedingRule] Running test with random seed: 123