1 files changed, 48 insertions, 0 deletions
diff --git a/test/junit/scala/collection/ReusableBuildersTest.scala b/test/junit/scala/collection/ReusableBuildersTest.scala
new file mode 100644
index 0000000000..8dd1a37adf
--- /dev/null
+++ b/test/junit/scala/collection/ReusableBuildersTest.scala
@@ -0,0 +1,48 @@
+package scala.collection
+
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+import org.junit.Test
+
+/* Tests various maps by making sure they all agree on the same answers. */
+@RunWith(classOf[JUnit4])
+class ReusableBuildersTest {
+  // GrowingBuilders are NOT reusable but can clear themselves
+  @Test
+  def test_SI8648() {
+    val b = collection.mutable.HashSet.newBuilder[Int]
+    b += 3
+    b.clear
+    assert(!b.isInstanceOf[collection.mutable.ReusableBuilder[_,_]])
+    assert(b.isInstanceOf[collection.mutable.GrowingBuilder[_,_]])
+    assert(b.result == Set[Int]())
+  }
+
+  // ArrayBuilders ARE reusable, regardless of whether they returned their internal array or not
+  @Test
+  def test_SI9564() {
+    val b = Array.newBuilder[Float]
+    b += 3f
+    val three = b.result
+    b.clear
+    b ++= (1 to 16).map(_.toFloat)
+    val sixteen = b.result
+    b.clear
+    b += 0f
+    val zero = b.result
+    assert(b.isInstanceOf[collection.mutable.ReusableBuilder[_,_]])
+    assert(three.toList == 3 :: Nil)
+    assert(sixteen.toList == (1 to 16))
+    assert(zero.toList == 0 :: Nil)
+  }
+
+  @Test
+  def test_reusability() {
+    val bl = List.newBuilder[String]
+    val bv = Vector.newBuilder[String]
+    val ba = collection.mutable.ArrayBuffer.newBuilder[String]
+    assert(bl.isInstanceOf[collection.mutable.ReusableBuilder[_, _]])
+    assert(bv.isInstanceOf[collection.mutable.ReusableBuilder[_, _]])
+    assert(!ba.isInstanceOf[collection.mutable.ReusableBuilder[_, _]])
+  }
+}