connutil

Utility net.Conns for testing and more

Usage

$ go get github.com/cbeuw/connutil

See the full documentation here: https://pkg.go.dev/github.com/cbeuw/connutil?tab=doc

AsyncPipe() is a function that returns two ends of an in-memory pipe, with both ends implementing net.Conn. They are fully duplex and behave similar to two ends of a TCP connection. It is a drop-in replacement for net.Pipe(), but is asynchronous and buffered.

oneEnd, otherEnd := AsyncPipe()
oneEnd.Write([]byte("hello")) // will not block

receivingBuffer := make([]byte, 5)
io.ReadFull(otherEnd, receivingBuffer)
// string(receivingBuffer) == "hello"

go func(){
    otherEnd.Write([]byte("world"))
}()
oneEnd.Read(receivingBuffer) // will block until there is something to read

Examples

To test a tls implementation, for instance

package test

import (
    "crypto/tls"
    "testing"

    "github.com/cbeuw/connutil"
)

func TestTLS(t *testing.T){
    clientEnd, serverEnd := connutil.AsyncPipe()

    clientConn := tls.Client(clientEnd, fooClientConfig)
    serverConn := tls.Server(serverEnd, fooServerConfig)

    // do things with clientConn and serverConn...
    // e.g.
    clientConn.Handshake()
    go serverConn.Handshake()
    err := clientConn.VerifyHostname("example.com")
    if err != nil {
        t.Error(err)
    }
}

Or to test the behaviour of an http server

package test

import(
    "crypto/rand"
    "io"
    "net/http"
    "testing"

    "github.com/cbeuw/connutil"
)

func TestHttp(t *testing.T){
    // DialerListener returns a pair of Dialer and net.Listener
    dialer, listener := connutil.DialerListener(128)

    go http.Serve(listener, fooHandler)
    
    // Here you get one end of an async pipe. http.Serve will get the other end from
    // listener.Accept() 
    clientConn, err := dialer.Dial("","")
    if err != nil {
        // handle error
    }
    
    // Do stuff with the client conn...
    clientConn.Write([]byte("GET ..."))
    // Writing junk to the server
    io.Copy(clientConn, rand.Reader)
}