SI-7883 - don't iterate over all keys in MapWrapper.containsKey()

1 files changed, 49 insertions, 0 deletions

diff --git a/test/junit/scala/collection/convert/MapWrapperTest.scala b/test/junit/scala/collection/convert/MapWrapperTest.scala
new file mode 100644
index 0000000000..060b6b5937
--- /dev/null
+++ b/test/junit/scala/collection/convert/MapWrapperTest.scala
@@ -0,0 +1,49 @@
+package scala.collection.convert
+
+import org.junit.Assert._
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+
+@RunWith(classOf[JUnit4])
+class MapWrapperTest {
+
+  /* Test for SI-7883 */
+  @Test
+  def testContains() {
+    import scala.collection.JavaConverters.mapAsJavaMapConverter
+    import scala.language.reflectiveCalls  // for accessing containsCounter
+
+    // A HashMap which throws an exception when the iterator() method is called.
+    // Before the fix for SI-7883, calling MapWrapper.containsKey() used to
+    // iterate through every element of the wrapped Map, and thus would crash
+    // in this case.
+    val scalaMap = new scala.collection.mutable.HashMap[String, String] {
+      var containsCounter = 0  // keep track of how often contains() has been called.
+      override def iterator = throw new UnsupportedOperationException
+
+      override def contains(key: String): Boolean = {
+        containsCounter += 1
+        super.contains(key)
+      }
+    }
+
+    val javaMap = scalaMap.asJava
+
+    scalaMap("hello") = "world"
+    scalaMap(null) = "null's value"
+
+    assertEquals(0, scalaMap.containsCounter)
+    assertTrue(javaMap.containsKey("hello"))     // positive test
+    assertTrue(javaMap.containsKey(null))        // positive test, null key
+
+    assertFalse(javaMap.containsKey("goodbye"))  // negative test
+    // Note: this case does NOT make it to scalaMap's contains() method because the runtime
+    // cast fails in MapWrapper, so the containsCounter is not incremented in this case.
+    assertFalse(javaMap.containsKey(42))         // negative test, wrong key type
+
+    assertEquals(Some("null's value"), scalaMap.remove(null))
+    assertFalse(javaMap.containsKey(null))       // negative test, null key
+    assertEquals(4, scalaMap.containsCounter)
+  }
+}