Humble Object Example

Channel.kt

package org.geepawhill.rws

import java.io.*
import java.net.Socket

class SocketWrapper(val input: InputStream, val output: OutputStream, val machine: String) {
    constructor(socket: Socket) : this(socket.getInputStream(), socket.getOutputStream(), socket.inetAddress.toString())
}

class Channel(socket: SocketWrapper, private val listener: Listener) : Talker, Runnable {
    private val input: BufferedReader = BufferedReader(
        InputStreamReader(
            socket.input
        )
    )
    private val output: PrintStream = PrintStream(socket.output, true)

    init {
        println("Channel: ${socket.machine}")
        listener.birth(this)
        println("Waiting for client...")
    }

    override fun run() {
        try {
            while (true) {
                val message = input.readLine()
                if (message != null) listener.hear(this, message)
                break
            }
        } finally {
            closeQuietly()
        }
    }

    private fun closeQuietly() {
        try {
            listener.death(this)
            input.close()
            output.close()
        } catch (ex: IOException) {
        }
    }

    @Synchronized
    override fun say(message: String) {
        output.println(message)
    }
}

ChannelTest.kt

package org.geepawhill.rws

import org.assertj.core.api.Assertions.assertThat
import org.junit.jupiter.api.Test
import java.io.ByteArrayOutputStream

class ChannelTest {
    val listener = TestingListener()
    val inputStream = "This is a string".byteInputStream()
    val outputStream = ByteArrayOutputStream()
    val socket = SocketWrapper(inputStream, outputStream, "TEST")

    @Test
    fun `gives birth message`() {
        val channel = Channel(socket, listener)
        assertThat(listener.talkers).containsExactly(channel)
    }

    @Test
    fun `passes message on`() {
        val channel = Channel(socket, listener)
        channel.run()
        assertThat(listener.messages).containsExactly(ReceivedSay(channel, "This is a string"))
    }

    @Test
    fun `dies on eof`() {
        // The input has one line, read during the run, and then has the same effect as the user closing the socket.
        val channel = Channel(socket, listener)
        channel.run()
        assertThat(listener.talkers).isEmpty()
    }

    @Test
    fun `says to output`() {
        val channel = Channel(socket, listener)
        channel.say("Hi mom!")
        channel.run()
        assertThat(outputStream.toByteArray()).isEqualTo("Hi mom!\r\n".toByteArray())
    }
}