Add a test to interrogate the expanded tree.

 - checks that only one function is synthesized
 - checks the set of vars created (TODO minimize these)
 - use x$1 rather than x1 for the freshened names for lifted vars.
 - make execContext a val, not a var.

4 files changed, 49 insertions, 6 deletions

diff --git a/src/main/scala/scala/async/Async.scala b/src/main/scala/scala/async/Async.scala
index 9f43b0b..4f7fa01 100644
--- a/src/main/scala/scala/async/Async.scala
+++ b/src/main/scala/scala/async/Async.scala
@@ -139,7 +139,7 @@ abstract class AsyncBase {
       // Initialize the state
       var state$async = 0
       // Resolve the execution context
-      var execContext$async = futureSystemOps.execContext.splice
+      val execContext$async = futureSystemOps.execContext.splice
       var onCompleteHandler$async: util.Try[Any] => Unit = null
 
       // Spawn a future to:
diff --git a/src/main/scala/scala/async/ExprBuilder.scala b/src/main/scala/scala/async/ExprBuilder.scala
index 09489d4..1a3f866 100644
--- a/src/main/scala/scala/async/ExprBuilder.scala
+++ b/src/main/scala/scala/async/ExprBuilder.scala
@@ -34,6 +34,8 @@ final class ExprBuilder[C <: Context, FS <: FutureSystem](val c: C, val futureSy
     val x1 = newTermName("x$1")
     val tr = newTermName("tr")
     val onCompleteHandler = suffixedName("onCompleteHandler")
+
+    def fresh(name: TermName) = newTermName(c.fresh("" + name + "$"))
   }
 
   private val execContext = futureSystemOps.execContext
@@ -295,7 +297,7 @@ final class ExprBuilder[C <: Context, FS <: FutureSystem](val c: C, val futureSy
     for (stat <- stats) stat match {
       // the val name = await(..) pattern
       case ValDef(mods, name, tpt, Apply(fun, args)) if fun.symbol == Async_await =>
-        val newName = c.fresh(name)
+        val newName = builder.name.fresh(name)
         toRename += (stat.symbol -> newName)
 
         asyncStates += stateBuilder.complete(args.head, newName, tpt, toRename).result // complete with await
@@ -309,7 +311,7 @@ final class ExprBuilder[C <: Context, FS <: FutureSystem](val c: C, val futureSy
       case ValDef(mods, name, tpt, rhs) =>
         checkForUnsupportedAwait(rhs)
 
-        val newName = c.fresh(name)
+        val newName = builder.name.fresh(name)
         toRename += (stat.symbol -> newName)
         // when adding assignment need to take `toRename` into account
         stateBuilder.addVarDef(mods, newName, tpt, rhs, toRename)
diff --git a/src/test/scala/scala/async/TestUtils.scala b/src/test/scala/scala/async/TestUtils.scala
index 0920659..bac22a3 100644
--- a/src/test/scala/scala/async/TestUtils.scala
+++ b/src/test/scala/scala/async/TestUtils.scala
@@ -40,11 +40,14 @@ trait TestUtils {
   }
 
   def eval(code: String, compileOptions: String = ""): Any = {
+    val tb = mkToolbox(compileOptions)
+    tb.eval(tb.parse(code))
+  }
+
+  def mkToolbox(compileOptions: String = "") = {
     val m = scala.reflect.runtime.currentMirror
     import scala.tools.reflect.ToolBox
-    val tb = m.mkToolBox(options = compileOptions)
-    val result = tb.eval(tb.parse(code))
-    result
+    m.mkToolBox(options = compileOptions)
   }
 
   def expectError(errorSnippet: String, compileOptions: String = "")(code: String) {
diff --git a/src/test/scala/scala/async/TreeInterrogation.scala b/src/test/scala/scala/async/TreeInterrogation.scala
new file mode 100644
index 0000000..7c277b1
--- /dev/null
+++ b/src/test/scala/scala/async/TreeInterrogation.scala
@@ -0,0 +1,38 @@
+package scala.async
+
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+import org.junit.Test
+import AsyncId._
+
+@RunWith(classOf[JUnit4])
+class TreeInterrogation {
+  @Test
+  def `a minimal set of vals are lifted to vars`() {
+    val cm = reflect.runtime.currentMirror
+    val tb = mkToolbox()
+    val tree = mkToolbox().parse(
+      """| import _root_.scala.async.AsyncId._
+        | async {
+        |   val x = await(1)
+        |   val y = x * 2
+        |   val z = await(x * 3)
+        |   z
+        | }""".stripMargin)
+    val tree1 = tb.typeCheck(tree)
+
+    // println(cm.universe.showRaw(tree1))
+
+    import tb.mirror.universe._
+    val functions = tree1.collect {
+      case f: Function => f
+    }
+    functions.size mustBe 1
+
+    val varDefs = tree1.collect {
+      case ValDef(mods, name, _, _) if mods.hasFlag(Flag.MUTABLE) => name
+    }
+    // TODO no need to lift `y` as it is only accessed from a single state.
+    varDefs.map(_.decoded).toSet mustBe(Set("state$async", "onCompleteHandler$async", "x$1", "z$1", "y$1"))
+  }
+}