Added Mono.cache(ttl)

Author: sinwe

src/main/scala/reactor/core/scala/publisher/Mono.scala

@@ -165,9 +165,9 @@ class Mono[T] private(private val jMono: JMono[T]) extends Publisher[T] with Map
     *
     * @return a replaying [[Mono]]
     */
-  final def cache(): Mono[T] = Mono[T](
-    jMono.cache()
-  )
+  final def cache(): Mono[T] = Mono[T](jMono.cache())
+
+  final def cache(ttl: Duration) = Mono(jMono.cache(ttl))
 
   /**
     * Prepare this [[Mono]] so that subscribers will cancel from it on a

src/test/scala/reactor/core/scala/publisher/MonoTest.scala

@@ -412,10 +412,17 @@ class MonoTest extends FreeSpec with Matchers with TableDrivenPropertyChecks wit
       number shouldBe a[ScalaNumber]
     }
 
-    ".cache should call the underlying cache method" in {
-      val jMono = spy(JMono.just(1))
-      Mono(jMono).cache()
-      Mockito.verify(jMono).cache()
+    ".cache" - {
+      "should call the underlying cache method" in {
+        val jMono = spy(JMono.just(1))
+        Mono(jMono).cache()
+        Mockito.verify(jMono).cache()
+      }
+      "with ttl should call the underlying cache method" in {
+        val jMono = spy(JMono.just(1))
+        Mono(jMono).cache(10 seconds)
+        Mockito.verify(jMono).cache(10 seconds)
+      }
     }
 
     ".cancelOn should cancel the subscriber on a particular scheduler" in {