tmenier/Flurl Flurl.Http.3.0.0 on GitHub

FlurlResponse introduced, primarily to enable inspecting response and deserializing body in separate steps. (#354)
Major overhaul of cookie functionality. (#506)
Overhaul of redirect handling. (#500)
Tests can be set up to return different fake responses depending on the URL or any other request conditions. (#481)
HttpTest.ForCallsTo(...).AllowRealHttp() for allowing real calls to be made in a test for specific URLs or any other request conditions. (#225)
New/more complete set of test assertions for headers and cookies. (#508)
All extension methods on Flurl.Url and string are now also available on System.Uri. (#489)
Providing a body for PostAsync, PutAsync, and PatchAsync now optional. (#515)

Making HTTP calls

Fluent methods that previously returned HttpResponseMessage (such GetAsync, PostAsync, etc) now return FlurlResponse. If you're using GetJsonAsync or chaining ReceiveXXX methods, this shouldn't break anything. (#354)
HttpCall is now FlurlCall, and several properties of FlurlCall and FlurlHttpException were moved or renamed. (#488)
Slightly different rules on when a redirect causes the verb to change to GET. (Never on 300, always on 303. #500)
Minor changes to CapturedStringContent constructors. (#452)

Headers

New collection type for IFlurlRequest.Headers and IFlurlClient.Headers. (#541)
HttpRequestMessage.GetHeaderValue and HttpResponseMessage.GetHeaderValue extension methods removed. (#553)
For multipart requests, Content-Type header for text parts allowed but not defaulted. (#452)
Cookie request header and Set-Cookie response headers are always visible in Headers collection of request and response. (#506)

CookiesEnabled removed at all settings levels. (#506)
Cookies, WithCookie and WithCookies removed from IFlurlClient. Use CookieSession instead. (#506)
IFlurlRequest.Cookies is now read-only IEnumerable<(string Name, string Value)>. Use WithCookies instead. (#506)

Testing

When asserting a specific URL was called, it must be a full string match rather than "contains" or "starts with". Add a * wildcard to the beginning or end if you need partial match behavior. (#323)
When faking responses in tests, the last response in the queue becomes "sticky" rather than falling back to empty 200 responses. (#482)
HttpTest.ResponseQueue public property has been removed. Underlying queue implementation changed significantly to support new features, and hopefully accessing it directly isn't needed. Use RespondWith methods to build the queues.
Minor changes/enhancements to HttpCallAssertion. (#483)

Other

UseCookies and AllowAutoRedirect are disabled on the default HttpClientHandler . Any custom factory-provided handler must do the same if Flurl's new cookie and redirect features are required. (#500 & #506)
Default HttpClient caching strategy based on host, scheme, and port, rather than just host. (#550)
Dropping support for older platforms. (#544)

tmenier/Flurl Flurl.Http.3.0.0 Flurl.Http 3.0 on GitHub