✨ Repeatable random numbers

[cbersch]

Description

For some of my tests I need repeatable random numbers, e.g. to test serialization of data objects, for which I must compare the resulting string with a reference string, which isn't currently possible.

For this, I would need to configure the seed of the random number generators used in the RegularExpressionGenerator and RandomNumericSequenceGenerator.

I could give it a try, but I'm not sure how to implement this in accordance with the library's design principles.

Suggestion

Maybe one could create a RandomProvider which is injected to the above two generators and provides a Random instance.

However, an instance of this RandomProvider must be delivered through several constructors to the DefaultPrimitiveBuilders constructor.
I think passing this option later at runtime isn't feasible and not reasonable.

public class RandomProvider
{
    public Random Random { get; private set; } = new Random();
    public void SetSeed(int seed) => Random = new Random(seed);
}

public interface IFixture
{
    void SetRandomSeed(int seed);
}

public class Fixture
{
    private readonly RandomProvider random = new RandomProvider();

    public Fixture() 
        : this(new RandomProvider()) { }

    public Fixture(RandomProvider random)
        : this(new DefaultEngineParts(random))
    {
        this.random = random ?? throw new ArgumentNullException(nameof(random));
    }

    public void SetRandomSeed(int seed) => random.SetSeed(seed);
}

// usage
IFixture fixture = new Fixture();
fixture.SetRandomSeed(27);