Top 20 NuGet fluent Packages

NSpectator is a ready-to-use solution for development using .NET with Context/Specification flavor. Toolset is intended to be used to drive development through specifying behavior and interaction at the unit level. NSpectator has no dependencies. Feel free to use any assertion library.
Library provides expression expanding. Used by Slant.Entity
Provides a fluent way to configure your DbContext's Model
Extensions and conventions for Relational Entity Framework Core configuration using FluentModelBuilder
My Tested ASP.NET Core MVC is a powerful testing library providing easy fluent interface to test the ASP.NET Core MVC framework.
Behaviour tree library with a fluent API for C#.
An easy to use console for writing colorful text - designed for .NET Core
Build query XPath with fluent style code
A simple library for authoring self-describing, or BDD-Style tests
A fluent API that you can use to build processes using the SOA concept and RESTful services.
Library contains set of actions and assertions used to configure Wiremock application.
Library contains set of actions and assertions used to create System tests and Component tests for microservices.
Little workflow engine with fluent definition Full documentation & sample here : http://www.alphablog.org/2013/01/12/a-little-workflow-engine/
Fluent interface for writing XML. Based on XmlOutput written by Mark S. Rasmussen. For examples see https://github.com/jtomkiew/XmlFluentDocument#example
FluendComparator is a .NET library which allows you compare generic objects effectively. It makes it easy to exclude certain properties from the comparison process and it can return the list of differences.
Client for calling HTTP REST APIs, mapping HTTP responses to C# types using a fluent API
This project implements a Finite-State-Machine (FSM) as a PCL (portable class library) designed to be used in games. Furthermore it implements even a Stack-Based-FSM (SBFSM). So you may tell it to 'continue with the last state before the active one'. You describe your FSM using a nice and well...
Command line tool used to measure REST API test coverage. Tool takes StoryLine.Rest tests execution report and compares it to API information stored in Swagger document.
Fluent library (essentially ILog) to introduce a complete application logging stack to your application. Fluent logging uses NLog to perist messages and comes with Ninject and Elmah connectors
Library contains set of actions and assertions used to create UI tests using Selenium WebDriver.