1 files changed, 72 insertions, 0 deletions
diff --git a/kamon-core-tests/src/test/scala/kamon/metric/TimerSpec.scala b/kamon-core-tests/src/test/scala/kamon/metric/TimerSpec.scala
new file mode 100644
index 00000000..3fc1e169
--- /dev/null
+++ b/kamon-core-tests/src/test/scala/kamon/metric/TimerSpec.scala
@@ -0,0 +1,72 @@
+package kamon.metric
+
+import kamon.Kamon
+import org.scalatest.{Matchers, WordSpec}
+
+
+class TimerSpec extends WordSpec with Matchers {
+  import TimerTestHelper._
+
+  "a Timer" should {
+    "record the duration between calls to .start() and .stop() in the StartedTimer" in {
+      val timer = Kamon.timer("timer-spec")
+      timer.start().stop()
+      timer.start().stop()
+      timer.start().stop()
+
+      timer.distribution().count shouldBe(3)
+    }
+
+    "ensure that a started timer can only be stopped once" in {
+      val timer = Kamon.timer("timer-spec")
+      val startedTimer = timer.start()
+      startedTimer.stop()
+      startedTimer.stop()
+      startedTimer.stop()
+
+      timer.distribution().count shouldBe(1)
+    }
+
+
+    "allow to record values and produce distributions as Histograms do" in {
+      val timer = Kamon.timer("test-timer")
+      timer.record(100)
+      timer.record(150, 998)
+      timer.record(200)
+
+      val distribution = timer.distribution()
+      distribution.min shouldBe(100)
+      distribution.max shouldBe(200)
+      distribution.count shouldBe(1000)
+      distribution.buckets.length shouldBe 3
+      distribution.buckets.map(b => (b.value, b.frequency)) should contain.allOf(
+        (100 -> 1),
+        (150 -> 998),
+        (200 -> 1)
+      )
+
+      val emptyDistribution = timer.distribution()
+      emptyDistribution.min shouldBe(0)
+      emptyDistribution.max shouldBe(0)
+      emptyDistribution.count shouldBe(0)
+      emptyDistribution.buckets.length shouldBe 0
+    }
+  }
+}
+
+object TimerTestHelper {
+
+  implicit class HistogramMetricSyntax(histogram: Histogram) {
+    def distribution(resetState: Boolean = true): Distribution = histogram  match {
+      case h: AtomicHdrHistogram  => h.snapshot(resetState).distribution
+      case h: HdrHistogram        => h.snapshot(resetState).distribution
+    }
+  }
+
+  implicit class TimerMetricSyntax(metric: TimerMetric) {
+    def distribution(resetState: Boolean = true): Distribution =
+      metric.refine(Map.empty[String, String]) match {
+        case t: TimerImpl     => t.histogram.distribution(resetState)
+      }
+  }
+}