Foundation HTTP testing

runServer_changes.swift

private func runServer(with condition: ServerSemaphore, delay: TimeInterval? = nil) throws {
        let start = 21961
        for port in start...(start+100) { //we must find at least one port to bind
            do {
                serverPort = port
                let test = try TestURLSessionServer(port: UInt16(port), delay: delay)
                try test.start(started: condition)
                try test.readAndRespond() {
                    test.stop()
                }
            } catch let e as ServerError {
                if e.operation != "bind" { continue }
                throw e
            }
        }
    }

TestURLSessionServer_changes.swift

public class TestURLSessionServer {
    let capitals: [String:String] = ["Nepal":"Kathmandu",
                                     "Peru":"Lima",
                                     "Italy":"Rome",
                                     "USA":"Washington, D.C.",
                                     "country.txt": "A country is a region that is identified as a distinct national entity in political geography"]
    let httpServer: _HTTPServer
    let delay: TimeInterval?
    
    
    public init (port: UInt16, delay: TimeInterval? = nil) throws {
        httpServer = try _HTTPServer.create(port: port)
        self.delay = delay
    }
    public func start(started: ServerSemaphore) throws {
        started.signal()
        try httpServer.listen(notify: started)
    }
   
    public func readAndRespond(callback: @escaping (Void) -> Void) throws {
        if let delay = self.delay {
            DispatchQueue.global().asyncAfter(deadline: .now() + delay) {
                try? self.httpServer.respond(with: self.process(request: self.httpServer.request()))
                callback()
            }
        } else {
            try httpServer.respond(with: process(request: httpServer.request()))
            callback()
        }
    }

    func process(request: _HTTPRequest) -> _HTTPResponse {
        if request.method == .GET {
            return getResponse(uri: request.uri)
        } else {
            fatalError("Unsupported method!")
        }
    }

    func getResponse(uri: String) -> _HTTPResponse {
        if uri == "/country.txt" {
            let text = capitals[String(uri.characters.dropFirst())]!
            return _HTTPResponse(response: .OK, headers: "Content-Length: \(text.characters.count)", body: text)
        }
        return _HTTPResponse(response: .OK, body: capitals[String(uri.characters.dropFirst())]!) 
    }

    func stop() {
        httpServer.stop()
    }
}