1 files changed, 46 insertions, 0 deletions
diff --git a/kamon-core/src/test/scala/kamon/metric/instrument/CounterSpec.scala b/kamon-core/src/test/scala/kamon/metric/instrument/CounterSpec.scala
new file mode 100644
index 00000000..26b3456d
--- /dev/null
+++ b/kamon-core/src/test/scala/kamon/metric/instrument/CounterSpec.scala
@@ -0,0 +1,46 @@
+package kamon.metric.instrument
+
+import kamon.LogInterceptor
+import kamon.metric.Entity
+import kamon.testkit.DefaultInstrumentFactory
+import org.scalatest.{Matchers, WordSpec}
+import uk.org.lidalia.slf4jext.Level
+import uk.org.lidalia.slf4jtest.TestLoggerFactory
+
+class CounterSpec extends WordSpec with Matchers with LogInterceptor with DefaultInstrumentFactory {
+  implicit val testLogger = TestLoggerFactory.getTestLogger(classOf[LongAdderCounter])
+
+  "a Counter" should {
+
+    "allow unit and bundled increments" in {
+      val counter = buildCounter("unit-increments")
+      counter.increment()
+      counter.increment()
+      counter.increment(40)
+
+      counter.snapshot().value shouldBe(42)
+    }
+
+    "warn the user and ignore attempts to decrement the counter" in {
+      val counter = buildCounter("attempt-to-decrement")
+      counter.increment(100)
+      counter.increment(100)
+      counter.increment(100)
+
+      interceptLog(Level.WARN) {
+        counter.increment(-10L)
+      }.head.getMessage() shouldBe(s"Ignored attempt to decrement counter [attempt-to-decrement] on entity [$defaultEntity]")
+
+      counter.snapshot().value shouldBe(300)
+    }
+
+    "reset the internal state to zero after taking snapshots" in {
+      val counter = buildCounter("reset-after-snapshot")
+      counter.increment()
+      counter.increment(10)
+
+      counter.snapshot().value shouldBe(11)
+      counter.snapshot().value shouldBe(0)
+    }
+  }
+}