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Fill random/edge-case value to target type for unit testing, supports both .NET Standard and Unity. This lib is similar as AutoFixture but has some different things.


NuGet: RandomFixtureKit

Install-Package RandomFixturekit

Unity: releases/RandomFixtureKit.unitypackage

or package.json exists on src/RandomFixtureKit.Unity/Assets/Scripts/RandomFixtureKit for unity package manager.

Table of Contents

How to use

// get single value
var value = FixtureFactory.Create<Foo>();

// get array
var values = FixtureFactory.CreateMany<Bar>();

// get temporal value(you can use this values to use invoke target method)
var (x, y, z) = FixtureFactory.Create<(int, string, short)>();

In the default, all fill values are random(and not includes null). This behaviour is configure by IGeneratorResolver resolver overload.

// default is NotNull resolver, the value is completely random
var value1 = FixtureFactory.Create<int>(resolver: StandardResolver.NotNull);

// you can change the EdgeCaseResolver, 
var value2 = FixtureFactory.Create<int>(resolver: StandardResolver.EdgeCase);

// you can change the default resolver.
FixtureFactory.Default = StandardResolver.EdgeCase;

// or make the new you combine resolver.
// this configuration uses string => fill Japanese Hiragana and others as NonNullResolver
var resolver = new CompositeResolver(new[] {
        new JapaneseHiraganaGenerator(stringLength:9),
    }, new[] {

// for fill interface type, need to map before call create
FixtureFactory.RegisterMap<IFoo, Foo>();
var v = FixtureFactory.Create<IFoo>(); // return Foo object


edge-case, for example int is filled int.MinValue, int.MaxValue, 0, -1 or 1. collection(array, list, etc...) is filled null, zero-elements, one-elements, nine-elements.

Custom Generator

Implement IGenerator and setup composite-resolver, you can control how generate values.

// for example, increment Id on create MyClass value.
public class MyClass
    public int Id { get; set; }
    public int Age { get; set; }
    public string Name { get; set; }

    public override string ToString()
        return (Id, Age, Name).ToString();

// Create IGenerator.
public class MyClassSequentialIdGenerator : IGenerator
    int sequence = 0;
    IGenerator fallbackGenerator = new Int32Generator();

    // this generator called if requires int value.
    public Type Type => typeof(int);

    public object Generate(in GenerationContext context)
        // check target int field belongs MyClass.
        if (context.FieldInfo != null)
            // auto-implemented property's field: <Id>k__BackingField
            if (context.FieldInfo.DeclaringType == typeof(MyClass) && context.FieldInfo.Name.StartsWith("<Id>"))
                return (sequence++);

        return fallbackGenerator.Generate(context);

// setup generator to use
var resolver = new CompositeResolver(new[] { new MyClassSequentialIdGenerator() }, new[] { StandardResolver.NonNull });
var fixture = new Fixture(resolver); // fixture is instance version of FixtureFactory

var foo = fixture.CreateMany<MyClass>(100);
foreach (var item in foo)

Author Info

This library is mainly developed by Yoshifumi Kawai(a.k.a. neuecc).
He is the CEO/CTO of Cysharp which is a subsidiary of Cygames.
He is awarding Microsoft MVP for Developer Technologies(C#) since 2011.
He is known as the creator of UniRx and MessagePack for C#.


This library is under the MIT License.


Fill random/edge-case value to target type for unit testing, supports both .NET Standard and Unity.




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