AutoFixure Fixture.Build().With() with different values

Question

Consider a class

class A
{
    public class NestedA
    {
        public string StrWithInt { get; set; }

        public string Str1 { get; set; }

        public string Str2 { get; set; }
    }

    public List<NestedA> Items { get; set; }
}

I am using AutoFixture framework for generating instances of class A with random contents.
The NestedA's class property StrWithInt is a string type but its value has to be a number, int value. So I am using a With() method to customize generation.

My code looks like below:

Random r = new Random();
Fixture fixture = new Fixture();
fixture.Customize<A.NestedA>(ob =>
    ob.With(p => p.StrWithInt, r.Next().ToString())
);
var sut = fixture.Build<A>().Create();

foreach (var it in sut.Items)
{
   Console.WriteLine($"StrWithInt: {it.StrWithInt}");
}
Console.ReadLine();

I get a such result.

StrWithInt: 340189285
StrWithInt: 340189285
StrWithInt: 340189285

All values are same. But I am expected to see different values of this property.
How Can I reach it?

Answer 1

The With(...) method has many overloads among which you can find the following:

IPostprocessComposer<T> With<TProperty>(
      Expression<Func<T, TProperty>> propertyPicker,
      Func<TProperty> valueFactory);

So you can use this one via passing factory of random numbers and after this result always will be different:

fixture.Customize<A.NestedA>(ob =>
    ob.With(p => p.StrWithInt, () => r.Next().ToString())
);

In your case you choose the static one which always assign the same value to the specified property.