Parameterized Object Mother in C# as an alternative to Test Data Builder pattern (thanks to named arguments with default values)

AddressObjectMother.cs

public static class AddressObjectMother
{
    public static Address Create(string street = "", string city = "", PostCode postCode = null)
    {
        if (postCode == null)
        {
            postCode = PostCodeObjectMother.Create();
        }
        
        return new Address(street, city, postCode);
    }
}

PostCodeObjectMother.cs

public static class PostCodeObjectMother
{
    public static PostCode Create(string postCode = "NL-1000")
    {
        return new PostCode(postCode);
    }
    
    public static PostCode CreateEmpty()
    {       
        return new PostCode();
    }
}

SampleCompostition.cs

var address = AddressObjectMother.Create(
  postCode: PostCodeObjectMother.CreateEmpty()
);