"adding" onto a rule

[mlapaglia]

can a rule on an object be added to after the original RuleFor? i'd like to add a OrNull() to every field for "chaos" testing without having to write the whole rule over again.

[bchavez]

Not exactly the most elegant, but here's one way to apply .OrNull/.OrDefault to all rules stored in a Faker<T> object:

void Main()
{
   var faker = new ChaosFaker<User>()
      .RuleFor(u => u.FirstName, f => f.Name.FirstName())
      .RuleFor(u => u.LastName, f => f.Name.LastName())
      .RuleFor(u => u.Age, f => f.Random.Number(18, 27))
      as ChaosFaker<User>;
   
   faker.Generate(5).Dump();
   
   faker.WithChaos();
   
   faker.Generate(5).Dump();
}

public class User
{
   public string FirstName;
   public string LastName;
   public int? Age;
}

public class ChaosFaker<T> : Faker<T> where T : class{
   
   public ChaosFaker<T> WithChaos()
   {
      var allRulesets = this.Actions.Values;
      foreach (var ruleSet in allRulesets)
      {
         foreach( var rule in ruleSet ){
            this.AddRule(rule.Key, (f, t) => rule.Value.Action(f, t).OrDefault(f));
         }
      }
      
      return this;
   }
}

This particular implementation above is a "one time use" kind of situation; ie: once you call .WithChaos() you can't go back because the original rule is overwritten by this.AddRule.

If you want to switch between "original" and "with null" on-demand, you'll need to keep a copy of the "old"/original population rule before overwriting it; and load the originals back.

Hope that helps. Feel free to carry on the conversation after I close the thread.

Thanks,
Brian