Single Abstract Method support: java8 test

Inspired by test/files/run/t7398.scala and sammy_poly.
Added some notes to original tests.

Elaborating on that note: we don't yet desugar `f(a)` to `f.sam(a)`,
like we do for regular functions: `f(a)` becomes `f.apply(a)`.

It seems pleasingly symmetrical and is easy to implement,
but not sure it's a good idea...

4 files changed, 37 insertions, 1 deletions

diff --git a/test/files/pos/sammy_poly.scala b/test/files/pos/sammy_poly.scala
index f03be4f8f5..c629be7166 100644
--- a/test/files/pos/sammy_poly.scala
+++ b/test/files/pos/sammy_poly.scala
@@ -1,6 +1,7 @@
 // test synthesizeSAMFunction where the sam type is not fully defined
 class T {
   trait F[T, U] { def apply(x: T): U }
+  // NOTE: the f(x) desugaring for now assumes the single abstract method is called 'apply'
   def app[T, U](x: T)(f: F[T, U]): U = f(x)
   app(1)(x => List(x))
 }
\ No newline at end of file
diff --git a/test/files/run/sammy_java8.flags b/test/files/run/sammy_java8.flags
new file mode 100644
index 0000000000..48fd867160
--- /dev/null
+++ b/test/files/run/sammy_java8.flags
@@ -0,0 +1 @@
+-Xexperimental
diff --git a/test/files/run/sammy_java8.scala b/test/files/run/sammy_java8.scala
new file mode 100644
index 0000000000..db9df7f5fe
--- /dev/null
+++ b/test/files/run/sammy_java8.scala
@@ -0,0 +1,34 @@
+import scala.tools.partest._
+
+// java8 version of sammy_poly.scala
+object Test extends CompilerTest {
+  import global._
+
+  override lazy val units: List[CompilationUnit] = {
+    global.settings.Xexperimental.value = true
+
+    // This test itself does not depend on JDK8.
+    javaCompilationUnits(global)(samSource) ++
+    compilationUnits(global)(useSamSource)
+  }
+
+  private def samSource = """
+//   trait F[T, U] { def apply(x: T): U }
+public interface F<T, U> {
+    U apply(T t);
+    default void yadayada() {
+        throw new UnsupportedOperationException("yadayada");
+    }
+}
+  """
+
+  private def useSamSource = """
+class T {
+  def app[T, U](x: T)(f: F[T, U]): U = f(x)
+  app(1)(x => List(x))
+}
+  """
+
+  // We're only checking we can compile it.
+  def check(source: String, unit: global.CompilationUnit): Unit = ()
+}
diff --git a/test/files/run/t7398.scala b/test/files/run/t7398.scala
index 493c4dcf40..4b46850768 100644
--- a/test/files/run/t7398.scala
+++ b/test/files/run/t7398.scala
@@ -21,6 +21,6 @@ public interface Iterator<E> {
 }
   """
 
-  // We're only checking we can parse it.
+  // We're only checking we can compile it.
   def check(source: String, unit: global.CompilationUnit): Unit = ()
 }