add metric inspection facility for tests

1 files changed, 45 insertions, 0 deletions

diff --git a/kamon-core/src/test/scala/kamon/testkit/MetricInspection.scala b/kamon-core/src/test/scala/kamon/testkit/MetricInspection.scala
new file mode 100644
index 00000000..d0681fb5
--- /dev/null
+++ b/kamon-core/src/test/scala/kamon/testkit/MetricInspection.scala
@@ -0,0 +1,45 @@
+package kamon.testkit
+
+import kamon.metric._
+import _root_.scala.collection.concurrent.TrieMap
+
+
+trait MetricInspection {
+
+  implicit class MetricSyntax(metric: Metric[_]) {
+    def valuesForTag(tag: String): Seq[String] = {
+      val instrumentsField = classOf[BaseMetric[_, _]].getDeclaredField("instruments")
+      instrumentsField.setAccessible(true)
+
+      val instruments = instrumentsField.get(metric).asInstanceOf[TrieMap[Map[String, String], _]]
+      val instrumentsWithTheTag = instruments.keys.filter(_.keys.find(_ == tag).nonEmpty)
+      instrumentsWithTheTag.map(t => t(tag)).toSeq
+    }
+  }
+
+  implicit class HistogramMetricSyntax(histogram: Histogram) {
+    def distribution(resetState: Boolean = true): Distribution =
+      histogram match {
+        case hm: HistogramMetric    => hm.refine(Map.empty[String, String]).distribution(resetState)
+        case h: AtomicHdrHistogram  => h.snapshot(resetState).distribution
+        case h: HdrHistogram        => h.snapshot(resetState).distribution
+      }
+  }
+
+  implicit class MinMaxCounterMetricSyntax(mmCounter: MinMaxCounter) {
+    def distribution(resetState: Boolean = true): Distribution =
+      mmCounter match {
+        case mmcm: MinMaxCounterMetric  => mmcm.refine(Map.empty[String, String]).distribution(resetState)
+        case mmc: SimpleMinMaxCounter   => mmc.snapshot(resetState).distribution
+      }
+  }
+
+  implicit class CounterMetricSyntax(counter: Counter) {
+    def value(resetState: Boolean = true): Long =
+      counter match {
+        case cm: CounterMetric    => cm.refine(Map.empty[String, String]).value(resetState)
+        case c: LongAdderCounter  => c.snapshot(resetState).value
+      }
+  }
+}
+