Top 20 NuGet testable Packages

An abstraction of appsettings allowing easy and testable retrieval of settings asynchronously from arbitrary sources.
A testable replacement for DateTime.
Provides a HttpClient that can be used in unit-tests. HttpClientMock allows to setup a HttpClient instance which returns a predefined response.
Library for defining validation rules, combine them to sets of rules and test objects against that rules.
Remove the ceremony from your test classes. Easily mock your dependencies using the testable pattern. AutoWrockTestable is an adaptation of Richard Cirerol's AutoMocking wrapper that uses StructureMap's AutoMocking assembly along with the popular MOQ mocking toolset to make it easy to test classes a...
Provides a dialog to show a ValidationSummary (Ifp.Validation package) in WPF.
Provides interface abstractions for System.IO filesystem entities. Also provides a default implementation of IFileSystem that provides the default behavior of the System.IO implementations.
Implements TestableFileSystem.Interfaces by forwarding to the .NET Framework or .NET Core.
Implements TestableFileSystem.Interfaces using a blazingly fast in-memory NTFS-based file system.
Plug-in for FluentFactory. Integrates Ninject IoC to the factory and provides fluent API for getting dependencies.
Interfaces to substitute System.IO calls in the .NET Framework and .NET Core.
Simple factory with fluent interface: thin, easy, testable. Use 'Get.The.Service' syntax for your common services in solution, delivered by IoC container.
Simple factory with fluent interface: thin, easy, testable. This is a slave factory, which can be derived from the base factory to provide additional getters also with possibility to override base getters.
Testable EntityFramework: Easy and straightforward way to test EF queries
A library for generating testable proxy classes.
A flexible and testable validator library for C#.
EMSm is a simple, TDD-testable hierarchical state machine library for .Net, perfectly suitable for developing the behavior of your embedded systems.