SI-9197 Duration.Inf not a singleton when deserialized

Made `Duration.Undefined`, `.Inf`, and `.MinusInf` all give back the singleton instance instead of creating a new copy by overriding readResolve.

This override can be (and is) private, which at least on Sun's JDK8 doesn't mess with the auto-generated SerialVersionUIDs.

Thus, the patch should make things strictly better: if you're on 2.11.7+ on JVMs which pick the same SerialVersionUIDs, you can recover singletons.  Everywhere else you were already in trouble anyway.

1 files changed, 24 insertions, 0 deletions

diff --git a/test/junit/scala/concurrent/duration/SerializationTest.scala b/test/junit/scala/concurrent/duration/SerializationTest.scala
new file mode 100644
index 0000000000..af90a10984
--- /dev/null
+++ b/test/junit/scala/concurrent/duration/SerializationTest.scala
@@ -0,0 +1,24 @@
+package scala.concurrent.duration
+
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+import org.junit.Test
+
+
+@RunWith(classOf[JUnit4])
+class SerializationTest {
+  @Test
+  def test_SI9197 {
+    def ser(a: AnyRef): Array[Byte] = {
+      val bais = new java.io.ByteArrayOutputStream
+      (new java.io.ObjectOutputStream(bais)).writeObject(a)
+      bais.toByteArray
+    }
+    def des(ab: Array[Byte]): AnyRef =
+      (new java.io.ObjectInputStream(new java.io.ByteArrayInputStream(ab))).readObject
+    
+    assert(Duration.Undefined eq des(ser(Duration.Undefined)))
+    assert(Duration.Inf eq des(ser(Duration.Inf)))
+    assert(Duration.MinusInf eq des(ser(Duration.MinusInf)))
+  }
+}