1 files changed, 108 insertions, 0 deletions
diff --git a/kamon-core/src/test/scala/kamon/metric/instrument/MinMaxCounterSpec.scala b/kamon-core/src/test/scala/kamon/metric/instrument/MinMaxCounterSpec.scala
new file mode 100644
index 00000000..cb03664c
--- /dev/null
+++ b/kamon-core/src/test/scala/kamon/metric/instrument/MinMaxCounterSpec.scala
@@ -0,0 +1,108 @@
+/* =========================================================================================
+ * Copyright © 2013-2014 the kamon project <http://kamon.io/>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+ * either express or implied. See the License for the specific language governing permissions
+ * and limitations under the License.
+ * =========================================================================================
+ */
+
+package kamon.metric.instrument
+
+import java.nio.LongBuffer
+
+import akka.actor.ActorSystem
+import com.typesafe.config.ConfigFactory
+import kamon.metric.CollectionContext
+import kamon.metric.instrument.Histogram.MutableRecord
+import org.scalatest.{ Matchers, WordSpecLike }
+
+class MinMaxCounterSpec extends WordSpecLike with Matchers {
+  val system = ActorSystem("min-max-counter-spec")
+  val minMaxCounterConfig = ConfigFactory.parseString(
+    """
+      |refresh-interval = 1 hour
+      |highest-trackable-value = 1000
+      |significant-value-digits = 2
+    """.stripMargin)
+
+  "the MinMaxCounter" should {
+    "track ascending tendencies" in new MinMaxCounterFixture {
+      mmCounter.increment()
+      mmCounter.increment(3)
+      mmCounter.increment()
+
+      val snapshot = collectCounterSnapshot()
+
+      snapshot.min should be(0)
+      snapshot.max should be(5)
+      snapshot.recordsIterator.toStream should contain allOf (
+        MutableRecord(0, 1), // min
+        MutableRecord(5, 2)) // max and current
+    }
+
+    "track descending tendencies" in new MinMaxCounterFixture {
+      mmCounter.increment(5)
+      mmCounter.decrement()
+      mmCounter.decrement(3)
+      mmCounter.decrement()
+
+      val snapshot = collectCounterSnapshot()
+
+      snapshot.min should be(0)
+      snapshot.max should be(5)
+      snapshot.recordsIterator.toStream should contain allOf (
+        MutableRecord(0, 2), // min and current
+        MutableRecord(5, 1)) // max
+    }
+
+    "reset the min and max to the current value after taking a snapshot" in new MinMaxCounterFixture {
+      mmCounter.increment(5)
+      mmCounter.decrement(3)
+
+      val firstSnapshot = collectCounterSnapshot()
+
+      firstSnapshot.min should be(0)
+      firstSnapshot.max should be(5)
+      firstSnapshot.recordsIterator.toStream should contain allOf (
+        MutableRecord(0, 1), // min
+        MutableRecord(2, 1), // current
+        MutableRecord(5, 1)) // max
+
+      val secondSnapshot = collectCounterSnapshot()
+
+      secondSnapshot.min should be(2)
+      secondSnapshot.max should be(2)
+      secondSnapshot.recordsIterator.toStream should contain(
+        MutableRecord(2, 3)) // min, max and current
+    }
+
+    "report zero as the min and current values if they current value fell bellow zero" in new MinMaxCounterFixture {
+      mmCounter.decrement(3)
+
+      val snapshot = collectCounterSnapshot()
+
+      snapshot.min should be(0)
+      snapshot.max should be(0)
+      snapshot.recordsIterator.toStream should contain(
+        MutableRecord(0, 3)) // min, max and current (even while current really is -3
+    }
+  }
+
+  trait MinMaxCounterFixture {
+    val collectionContext = new CollectionContext {
+      val buffer: LongBuffer = LongBuffer.allocate(64)
+    }
+
+    val mmCounter = MinMaxCounter.fromConfig(minMaxCounterConfig, system).asInstanceOf[PaddedMinMaxCounter]
+    mmCounter.cleanup // cancel the refresh schedule
+
+    def collectCounterSnapshot(): Histogram.Snapshot = mmCounter.collect(collectionContext)
+  }
+}