Fix TestServer for windows

There were two issues with the server tests on windows
1) Sometimes client connections fail on the first attempt but
   will succeed with retries
2) It is possible for named pipes to leak which causes subsequent
   tests to be unable to run
3) ClientTest did not handle lines with carriage returns correctly

Issue #1 is fixed with retries. Issue #2 is fixed by using a
unique temp directory for each test run. Issue #3 was fixed by
simplifying the output stream cache to only cache the bytes returned
and then letting scala do the line splitting for us in linesIterator.

After these changes, all of the server tests work on appveyor.

.appveyor.yml

@@ -155,4 +155,4 @@ for:
     - '%USERPROFILE%\.sbt'
 
   test_script:
-    - sbt "scripted actions/* classloader-cache/* nio/* watch/*" "serverTestProj/testOnly serverTestProj/testOnly testpkg.HandshakeTest"
+    - sbt "scripted actions/* classloader-cache/* nio/* watch/*" "serverTestProj/test"

server-test/src/test/scala/testpkg/ClientTest.scala

@@ -27,15 +27,9 @@ object ClientTest extends AbstractServerTest {
     def lines = cos.lines
   }
   class CachingOutputStream extends OutputStream {
-    private val lineBuffer = new mutable.ArrayBuffer[String]
-    private var byteBuffer = new mutable.ArrayBuffer[Byte]
-    override def write(i: Int) = {
-      if (i == 10) {
-        lineBuffer += new String(byteBuffer.toArray)
-        byteBuffer = new mutable.ArrayBuffer[Byte]
-      } else Util.ignoreResult(byteBuffer += i.toByte)
-    }
-    def lines = lineBuffer.toVector
+    private val byteBuffer = new mutable.ArrayBuffer[Byte]
+    override def write(i: Int) = Util.ignoreResult(byteBuffer += i.toByte)
+    def lines = new String(byteBuffer.toArray, "UTF-8").linesIterator.toSeq
   }
   class FixedInputStream(keys: Char*) extends InputStream {
     var i = 0

server-test/src/test/scala/testpkg/TestServer.scala

@@ -8,7 +8,8 @@
 package testpkg
 
 import java.io.{ File, IOException }
-import java.nio.file.Path
+import java.net.Socket
+import java.nio.file.{ Files, Path }
 import java.util.concurrent.{ LinkedBlockingQueue, TimeUnit }
 import java.util.concurrent.atomic.AtomicBoolean
 
@@ -37,10 +38,11 @@ trait AbstractServerTest extends TestSuite[Unit] {
   }
 
   override def setupSuite(): Unit = {
-    temp = targetDir / "test-server" / testDirectory
-    if (temp.exists) {
-      IO.delete(temp)
-    }
+    val base = Files.createTempDirectory(
+      Files.createDirectories(targetDir.toPath.resolve("test-server")),
+      "server-test"
+    )
+    temp = base.toFile
     val classpath = sys.props.get("sbt.server.classpath") match {
       case Some(s: String) => s.split(java.io.File.pathSeparator).map(file)
       case _               => throw new IllegalStateException("No server classpath was specified.")
@@ -191,8 +193,19 @@ case class TestServer(
   hostLog(s"wait $waitDuration until the server is ready to respond")
   waitForPortfile(waitDuration)
 
+  @tailrec
+  private def connect(attempt: Int): Socket = {
+    val res = try Some(ClientSocket.socket(portfile)._1)
+    catch { case _: IOException if attempt < 10 => None }
+    res match {
+      case Some(s) => s
+      case _ =>
+        Thread.sleep(100)
+        connect(attempt + 1)
+    }
+  }
   // make connection to the socket described in the portfile
-  val (sk, _) = ClientSocket.socket(portfile)
+  val sk = connect(0)
   val out = sk.getOutputStream
   val in = sk.getInputStream
   private val lines = new LinkedBlockingQueue[String]