How do I start a server before running a test suite in SBT?

Question

Problem is that if I do test in Test <<= (taskA, taskB) { (A, B) => A doFinally B or test in Test := (taskB dependsOn taskA).value and taskA is forked, then sbt execution doesn't continue to taskB and get's stuck indefinitely. It's caused by doFinally/dependsOn, because they probably makes it a single-threaded sequential execution. But I can't find any other way to order those 2 tasks, to make them run sequentially.

So far I've gotten this far :

lazy val startServer = taskKey[Unit]("Start PingPong Server before running Scala-JS tests")

lazy val jvm =
     project.in(file("jvm"))
        fork in (Test, runMain) := true
        startServer := {
          (runMain in Test).toTask(" com.example.PingPong").value
        }
      )

lazy val js =
    project.in(file("js"))
       test in Test <<= (startServer in Project("jvm", file("jvm")), test in(Test, fastOptStage)) {
         (startServer, test) => startServer doFinally test
       }
     )

The sbt execution stops on a task startServer that spawns a thread, even a daemon one. I tried fork in startServer := true but it didn't help.

I also tried dependsOn, but it also blocks :

test in Test := {
  (test in(Test, fastOptStage)).dependsOn(startServer in Project("jvm", file("jvm"))).value
}

If I do not start the server in the main class PingPong, it behaves as expected. Also if I do this, it works but it has a random order of execution and I don't know how to enforce it without doFinally.

test in Test := {
  (startServer in Project("jvm", file("jvm"))).value
  (test in(Test, fastOptStage)).value
}

I think I'm gonna have to try sbt-sequential or fork a new process.

score 2 · Answer 1 · answered Sep 10 '14 at 15:12

Instead of dealing with SBT I can suggest much more simple workaround. Create Class with static method to start server (it will check that server is not yet started), and in each test explicitly start this server. You'll need to set "fork in Test := true", to run server in separate JVM and shutdown it after tests finished.

I use this approach for starting Embedded Cassandra server for integration tests

In my case it's static method with Java, you can do the same with Scala and companion object.

  override def beforeAll() {
    log.info(s"Start Embedded Cassandra Server")
    EmbeddedCassandraServerHelper.startEmbeddedCassandra("/timeseries.yaml")
  }

and

public static void startEmbeddedCassandra(String yamlFile, String tmpDir) throws TTransportException, IOException, ConfigurationException {
        if (cassandraDaemon != null) {
            /* nothing to do Cassandra is already started */
            return;
        }

     // ... Start new server
}

I'm doing this too, I just need a way of starting that server from sbt via task from various other reasons ... It just needs to be forked, but sbt's fork just doesn't work, revolver does... — lisak, Sep 10 '14 at 16:06
Also in this particular case, you can't do what you suggest because the `js` project is compiled to javascript and run on phantomJS and the jvm project has java dependencies. As I need to test the scalaJS project, I can't depend on the JVM project that has Java dependencies that won't compile to javascript :-) It's kinda messy — lisak, Sep 10 '14 at 22:04

score 2 · Answer 2 · answered Sep 10 '14 at 16:00

For some reason none of these settings forks a new process :

fork := true
fork in runMain := true
fork in Test := true
fork in (Test, runMain) := true

That's why sequential dependsOn/doFinally blocks because the process is not forked...

I tried exactly the same with revolver and it works. I recommend revolver to everybody who is trying to fork a process in sbt, because one can't rely the sbt's fork at least from this experience.

lazy val startServer = taskKey[Unit]("Start PingPong Server before running JS tests")

lazy val jvm =
     project.in(file("jvm"))
        mainClass in Revolver.reStart := Option("com.example.PingPong"),
        startServer := {
          (Revolver.reStart in Test).toTask("").value
        }
      )

lazy val js =
    project.in(file("js"))
       test in Test := (test in(Test, fastOptStage)).dependsOn(startServer in Project("jvm", file("jvm"))).value
     )

How do I start a server before running a test suite in SBT?

2 Answers2

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