The most popular and friendly mocking library for .NET ```csharp var mock = new Mock(); // WOW! No record/replay weirdness?! :) mock.Setup(library => library.DownloadExists("2.0.0.0")) .Returns(true); // Use the Object property on the mock to get a reference to the object // implementing ILoveThisLibrary, and then exercise it by calling // methods on it ILoveThisLibrary lovable = mock.Object; bool download = lovable.DownloadExists("2.0.0.0"); // Verify that the given method was indeed called with the expected value at most once mock.Verify(library => library.DownloadExists("2.0.0.0"), Times.AtMostOnce()); ``` Moq also is the first and only library so far to provide Linq to Mocks, so that the same behavior above can be achieved much more succinctly: ```csharp ILoveThisLibrary lovable = Mock.Of(l => l.DownloadExists("2.0.0.0") == true); // Exercise the instance returned by Mock.Of by calling methods on it... bool download = lovable.DownloadExists("2.0.0.0"); // Simply assert the returned state: Assert.True(download); // If you want to go beyond state testing and want to // verify the mock interaction instead... Mock.Get(lovable).Verify(library => library.DownloadExists("2.0.0.0")); ``` You can think of Linq to Mocks as "from the universe of mocks, give me one whose behavior matches this expression". Check out the [Quickstart](https://github.com/devlooped/moq/wiki/Quickstart) for more examples! # Sponsors [](https://github.com/clarius) [](https://github.com/KirillOsenkov) [](https://github.com/MFB-Technologies-Inc) [](https://github.com/decriptor) [](https://github.com/torutek-gh) [](https://github.com/drivenet) [](https://github.com/AshleyMedway) [](https://github.com/Keflon) [](https://github.com/tbolon) [](https://github.com/kfrancis) [](https://github.com/twenzel) [](https://github.com/Giorgi) [](https://github.com/unoplatform) [](https://github.com/dansiegel) [](https://github.com/rbnswartz) [](https://github.com/jfoshee) [](https://github.com/Mrxx99) [](https://github.com/eajhnsn1) [](https://github.com/IxTechnologies) [](https://github.com/davidjenni) [](https://github.com/Jonathan-Hickey) [](https://github.com/okyrylchuk) [](https://github.com/akunzai) [](https://github.com/jakobt) [](https://github.com/seanalexander) [](https://github.com/tinohager) [](https://github.com/ploeh) [](https://github.com/KenBonny) [](https://github.com/SimonCropp) [](https://github.com/agileworks-eu) [](https://github.com/sorahex) [](https://github.com/arsdragonfly) [](https://github.com/vezel-dev) [](https://github.com/ChilliCream) [](https://github.com/4OTC) [](https://github.com/v-limo) [](https://github.com/brooke-hamilton) [](https://github.com/sponsors/devlooped)   [Learn more about GitHub Sponsors](https://github.com/sponsors)