FactoryBot

FactoryBot is a tool to generate test objects with random data. Inspired by factory_girl.

Sometimes it may be really helpful for unit tests, performance test, any kind of proof of concept to generate random data.

For example:

Bot.Define(x => new Model({ Text = x.Strings.Any() });
var model = Bot.Build<Model>();

Now FactoryBot supports generators for following types:

int
long
short
byte
double
float
decimal
bool
string
DateTime
TimeSpan
Guid
and any enum type

Install

To install FactoryBot run:

Install-Package FactoryBot

Define Model Generators

FactoryBot support two models on defining model generation: manual and auto.

Auto mode

In auto mode FactoryBot goes over all public properties with public setters and binds predefined generators to it. Here is how you can use it:

Bot.DefineAuto<AllTypesModel>();
var model = Bot.Build<AllTypesModel>();

Manual Mode

In manual mode you should specify a generator per each property you want to be set:

Bot.Define(x => new AllTypesModel
{
    Boolean = x.Boolean.Any(),
    Byte = x.Byte.RandomFromList(3, 4, 5, 10, 12, 100),
    DateTime = x.Dates.AfterNow(),
    Decimal = x.Decimal.Any(-1000000, 1000000),
    Double = x.Double.SequenceFromList(12.45, 66.1234, 444.4),
    Enum = x.Enums.RandomFromList(EnumModel.First, EnumModel.Last),
    Float = x.Float.Any(),
    Integer = x.Integer.Any(0, 500),
    Long = x.Long.Any(),
    Short = x.Short.Any(-100, 100),
    String = x.Address.Country(),
    TimeSpan = x.Time.Any()
});

var model = Bot.Build<AllTypesModel>();

Build Mutation

There is an ability to change one particular model during a build.

One way is to provide some modifiers to Build method:

var model = Bot.Build<AllTypesModel>(x => x.Byte = 10, x => x.DateTime = DateTime.UtcNow);

Another way is to use BuildCustom method and provide define expression again to substitute some generators:

var model = Bot.BuildCustom(x => new Model1(5, x.Keep<string>()));

Sometimes you need to change generator in constructor but you want to keep other ones untouched. For this call Keep method as it showed above.

Other features

Build Sequence

Sometimes it's required to generate array of models. It can be easily done BuildSequence method. The method returns IEnumerable<T> and works as yield generator and generates infinite sequence of objects. To not creating infinite loops or generation OutOfMemoryExceptions in your programs the method has protection and if you try to generate more than 100 object you will get an exception. To disable this protection pass true as infinite parameter.

// generates sequence of 10 elements
Bot.BuildSequence<AllTypesModel>().Take(10).ToList().ForEach(x => Console.WriteLine(x)); 

// throws and error
foreach (var model in Bot.BuildSequence<AllTypesModel>()) 
{
  Console.WriteLine(model);
}

// creates an infinite loop
foreach (var model in Bot.BuildSequence<AllTypesModel>(true)) 
{
  Console.WriteLine(model);
}

mezm/factorybot