Conjecture.NET

Property-based testing for .NET — a ground-up port of Python's Hypothesis to C#.

Write tests that describe what your code should do, and let Conjecture generate hundreds of random inputs to find the edge cases you'd never think of. When it finds a failure, it automatically shrinks the input to the smallest possible counterexample.

Quick Example

using Conjecture.Xunit;

public class SortTests
{
    [Property]
    public bool Sorting_is_idempotent(List<int> items)
    {
        var sorted = items.OrderBy(x => x).ToList();
        var sortedTwice = sorted.OrderBy(x => x).ToList();
        return sorted.SequenceEqual(sortedTwice);
    }
}

No hand-written test cases. Conjecture generates random lists, runs the property 100 times, and if it fails, shrinks the input to the minimal failing case.

Features

  • Automatic test generation — generates random inputs from type-aware strategies
  • Intelligent shrinking — finds the smallest failing input via byte-stream minimization
  • LINQ composition — build complex strategies with Select, Where, SelectMany
  • All major frameworks — xUnit v2, xUnit v3, NUnit, MSTest
  • Source generators — derive strategies for your types with [Arbitrary]
  • Roslyn analyzers — catch common mistakes at compile time
  • Stateful testing — model systems as state machines and explore command sequences
  • Targeted testing — steer generation toward extremes with Target.Maximize / Target.Minimize
  • Recursive strategies — generate bounded-depth trees and self-referential types
  • Example database — persist failing inputs for automatic regression prevention
  • Structured logging — structured events for generation, shrinking, and targeting phases

Install

# Pick the adapter for your test framework:
dotnet add package Conjecture.Xunit      # xUnit v2
dotnet add package Conjecture.Xunit.V3   # xUnit v3
dotnet add package Conjecture.NUnit      # NUnit
dotnet add package Conjecture.MSTest     # MSTest

Get Started

Edit this page