QuickFuzzr

A type-walking cheetah with a hand full of random.

Generate realistic test data and fuzz your domain models using composable LINQ expressions.

Examples

It Just Works

Fuzzr.One<Person>().Generate();
// Results in => Person { Name = "ddnegsn", Age = 18 }

Configurable

var fuzzr =
    // Generate complete customer with orders and payments
    from counter in Fuzzr.Counter("my-key") // <= keyed auto incrementing int
    from customer in Fuzzr.One(() => new Customer($"Customer-{counter}"))
    from orders in Fuzzr.One<Order>()
        .Apply(customer.PlaceOrder) // <= add order to customer
        .Many(1, 3) // <= add between 1 and 3 random orders
    from payment in Fuzzr.One<Payment>()
        .Apply(p => p.Amount = orders.Sum(o => o.Total)) // <= calculate total from orders
        .Apply(customer.MakePayment) // <= add payment to customer
    select customer;
fuzzr.Many(2).Generate();

Output:

[
    Customer {
        Name: "Customer-1",
        Orders: [ Order { Total: 42.72 }, Order { Total: 67.24 } ],
        Payments: [ Payment { Amount: 109.96 } ]
    },
    Customer {
        Name: "Customer-2",
        Orders: [ Order { Total: 10.50 }, Order { Total: 14.66 }, Order { Total: 60.86 } ],
        Payments: [ Payment { Amount: 86.02 } ]
    }
]

Highlights

• Zero-config generation: Fuzzr.One<T>() works out of the box.
• LINQ-composable: Build complex fuzzrs from simple parts.
• Configurable defaults: Fine-tune generation with Configr.
• Recursive object graphs: Automatic depth-controlled nesting.
• Seed-based reproducibility: Deterministic results for reliable tests.
• Built for Devs: Clean LINQ workflows and Elm-style errors that guide you to the fix.

Installation

QuickFuzzr is available on NuGet:

Install-Package QuickFuzzr

Or via the .NET CLI:

dotnet add package QuickFuzzr

Documentation

QuickFuzzr is fully documented, with real, executable examples for every feature, and every statement in the docs is backed by a test.

You can explore it here:

• Table of Contents
• One File Guide
• One File Reference

Roadmap

• Add a 'When Things Go Wrong' chapter to reference.
• Benchmarks: Only believe the measured hype.
• Add the missing Primitives: DateTimeOffset, NInt, NUint, ...
• Expand the Cookbook with more real-world recipes
• QuickFuzzr.Reactor: Convention-based generation and reusable patterns.
• QuickFuzzr.Evil: For all your property-based testing needs.

License

This project is licensed under the MIT License.

Addendum

The How and Why of QuickFuzzr: From Kitten to Cheetah.