Add test for pickled refinement types bug (#610).

sbt/src/sbt-test/compiler-project/inc-pickled-refinement/build.sbt

@@ -0,0 +1,7 @@
+InputKey[Unit]("check-number-of-compiler-iterations") <<= inputTask { (argTask: TaskKey[Seq[String]]) =>
+  (argTask, compile in Compile) map { (args: Seq[String], a: sbt.inc.Analysis) =>
+    assert(args.size == 1)
+    val expectedIterationsNumber = args(0).toInt
+    assert(a.compilations.allCompilations.size == expectedIterationsNumber, "a.compilations.allCompilations.size = %d (expected %d)".format(a.compilations.allCompilations.size, expectedIterationsNumber))
+  }
+}

sbt/src/sbt-test/compiler-project/inc-pickled-refinement/changes/Impl1.scala

@@ -0,0 +1,5 @@
+package test3
+
+class Impl extends B with A with C {
+  def bleep = println("fooo")
+}

sbt/src/sbt-test/compiler-project/inc-pickled-refinement/src/main/scala/A.scala

@@ -0,0 +1,3 @@
+package test3
+
+trait A

sbt/src/sbt-test/compiler-project/inc-pickled-refinement/src/main/scala/B.scala

@@ -0,0 +1,9 @@
+package test3
+
+trait B { self: A with C => 
+  class Inner {
+    def b = B.this
+  }
+
+  def ref: Impl = throw new RuntimeException
+}

sbt/src/sbt-test/compiler-project/inc-pickled-refinement/src/main/scala/C.scala

@@ -0,0 +1,3 @@
+package test3
+
+trait C { }

sbt/src/sbt-test/compiler-project/inc-pickled-refinement/src/main/scala/Impl.scala

@@ -0,0 +1,5 @@
+package test3
+
+class Impl extends B with A with C {
+  def bleep = println("foo")
+}

sbt/src/sbt-test/compiler-project/inc-pickled-refinement/test

@@ -0,0 +1,14 @@
+# Tests if refinement types are pickled correctly so they
+# do not introduce unnecessary compile iterations
+# See https://issues.scala-lang.org/browse/SI-6596,
+#     https://github.com/harrah/xsbt/issues/610
+
+# introduces first compile iteration
+> compile
+# this change is local to method and does not change api so introduces
+# only one additional compile iteration
+$ copy-file changes/Impl1.scala src/main/scala/Impl.scala
+# second iteration
+> compile
+# check if there are only two compile iterations performed
+> check-number-of-compiler-iterations 2