diff --git a/.appveyor.yml b/.appveyor.yml
index f9277ae44..0c3f595a1 100644
--- a/.appveyor.yml
+++ b/.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"
diff --git a/server-test/src/test/scala/testpkg/ClientTest.scala b/server-test/src/test/scala/testpkg/ClientTest.scala
index dc85e05ef..145f12e0f 100644
--- a/server-test/src/test/scala/testpkg/ClientTest.scala
+++ b/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
diff --git a/server-test/src/test/scala/testpkg/TestServer.scala b/server-test/src/test/scala/testpkg/TestServer.scala
index 86c0d5e56..b5a45abdb 100644
--- a/server-test/src/test/scala/testpkg/TestServer.scala
+++ b/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]