Add scripted test

sbt-app/src/sbt-test/reporter/command-progress/build.sbt

@@ -0,0 +1,39 @@
+commandProgress += new ExecuteProgress2 {
+  override def beforeCommand(cmd: String, state: State): Unit = {
+    EventLog.logs += (s"BEFORE: $cmd")
+    // assert that `state` is the current state indeed
+    assert(state.currentCommand.isDefined)
+    assert(state.currentCommand.get.commandLine == cmd)
+  }
+  override def afterCommand(cmd: String, result: Either[Throwable, State]): Unit = {
+    EventLog.logs += (s"AFTER: $cmd")
+    result.left.foreach(EventLog.errors +=)
+  }
+  override def initial(): Unit = {}
+  override def afterRegistered(
+      task: Task[_],
+      allDeps: Iterable[Task[_]],
+      pendingDeps: Iterable[Task[_]]
+  ): Unit = {}
+  override def afterReady(task: Task[_]): Unit = {}
+  override def beforeWork(task: Task[_]): Unit = {}
+  override def afterWork[A](task: Task[A], result: Either[Task[A], Result[A]]): Unit = {}
+  override def afterCompleted[A](task: Task[A], result: Result[A]): Unit = {}
+  override def afterAllCompleted(results: RMap[Task, Result]): Unit = {}
+  override def stop(): Unit = {}
+}
+
+val check = taskKey[Unit]("Check basic command events")
+val checkParseError = taskKey[Unit]("Check that parse error is recorded")
+
+check := {
+  def hasEvent(cmd: String): Boolean =
+    EventLog.logs.contains(s"BEFORE: $cmd") && EventLog.logs.contains(s"AFTER: $cmd")
+
+  assert(hasEvent("compile"), "Missing command event `compile`")
+  assert(hasEvent("+compile"), "Missing command event `+compile`")
+}
+
+checkParseError := {
+  assert(EventLog.errors.exists(_.getMessage.toLowerCase.contains("not a valid command")))
+}

sbt-app/src/sbt-test/reporter/command-progress/project/EventLog.scala

@@ -0,0 +1,8 @@
+import scala.collection.mutable.ListBuffer
+
+object EventLog {
+  val logs = ListBuffer.empty[String]
+  val errors = ListBuffer.empty[Throwable]
+
+  def reset(): Unit = logs.clear()
+}

sbt-app/src/sbt-test/reporter/command-progress/test

@@ -0,0 +1,5 @@
+> compile
+> +compile
+> check
+-> asdf
+> checkParseError