Switchknife.Testing.Http 0.1.0

Switchknife.Testing.Http

A stub HttpMessageHandler for tests of code that takes an HttpClient. It answers each request from a function and records it, so no test reaches the network. No dependency beyond the BCL and none on a test framework: it works the same under xUnit 2, xUnit v3 or anything else.

var stub = new StubHttpHandler((request, body) => request.RequestUri!.AbsolutePath switch
{
    "/repos/o/r/pulls" => StubHttpHandler.Json("""{"number":7}""", HttpStatusCode.Created),
    _ => new HttpResponseMessage(HttpStatusCode.NotFound),
});
var client = new PullRequests(stub.Client("https://api.example.test/"));

await client.OpenAsync("o", "r", "Title");

var (method, uri, body, headers) = Assert.Single(stub.Requests);
Assert.Equal(HttpMethod.Post, method);
Assert.Equal("/repos/o/r/pulls", uri.PathAndQuery);
Assert.Equal("Bearer the-token", headers["Authorization"]);

• new StubHttpHandler((request, body) => response): the body is read once, before the function runs, and passed to it as a string (empty when the request has none). The function may throw to simulate a dropped connection.
• new StubHttpHandler(async (request, body, ct) => response): for responses that wait, such as a hanging upstream that only the caller's timeout or cancellation ends.
• StubHttpHandler.Sequence(reply1, reply2, ...): the n-th request gets the n-th reply; when they run out, the last one keeps answering (a poller that sees the same state again). Assert on Requests.Count to catch extra calls.
• Requests: every request in arrival order as RecordedRequest(Method, Uri, Body, Headers), copied when it arrived, so it is still readable after the caller disposed the request and its content. Headers holds request and content headers, case-insensitive, repeated values joined with ", ". Recording is thread-safe.
• StubHttpHandler.Json(json, status = 200): a response with application/json; charset=utf-8 content.
• Client(baseAddress?): an HttpClient over the stub; disposing the client leaves the stub and its records alone.

Limits:

• Body is the content decoded as text (its charset, else UTF-8). Reading it buffers the content, so a test of a binary upload can still read request.Content as bytes inside the function.
• No routing table: route inside the function with a switch on method and path, as above.