Property based testing in C#–How to change the number of runs?

After gaving my talk about Property Based Testing, I was contacted by one of the participants with the following question:

How to change the number of test runs?

In case you have no idea what I’m talking about; by default the property based testing library(FSCheck in my case) will generate a number of inputs and run the tests  for all these inputs. By default 100 inputs are generated and tested:

 

You can change the number of test runs either by setting the MaxTest property on the [Property] attribute:

	[Property(MaxTest =200)]
	public Property Adding_Two_Numbers_Doesnt_Depend_On_Parameter_Order_3(Tuple<int, int> values)
	{
	return (Add(values.Item1, values.Item2) == Add(values.Item1, values.Item2)).ToProperty();
	}

view raw MaxTest.cs hosted with ❤ by GitHub

Or by passing a configuration object when calling Prop.ForAll

	[Fact]
	public void WhenIAddTwoRandomNumbersTheResultShouldNotDependOnParameterOrder_2()
	{
	var config = Configuration.Default;
	config.MaxNbOfTest = 200;
	var addingTwoRandomNumbers = (int x, int y) => Add(x, y) == Add(y, x);
	Prop.ForAll(new Func<int, int, bool>(addingTwoRandomNumbers))
	.Check(config);
	}

view raw Prop.cs hosted with ❤ by GitHub