Implement kafka consumer metrics

- bump Micrometer version 1.0.8 -> 1.1.5

Change-Id: I7a00fbf252df0f31f12f8743e8719701bd282ce2
Issue-ID: DCAEGEN2-1626
Signed-off-by: Filip Krzywka <filip.krzywka@nokia.com>

9 files changed, 200 insertions, 105 deletions

diff --git a/pom.xml b/pom.xml
index 662e17e8..2d2fb544 100644
--- a/pom.xml
+++ b/pom.xml
@@ -520,7 +520,7 @@
             <dependency>
                 <groupId>io.micrometer</groupId>
                 <artifactId>micrometer-registry-prometheus</artifactId>
-                <version>1.0.8</version>
+                <version>1.1.5</version>
             </dependency>
             <dependency>
                 <groupId>org.onap.dcaegen2.services.sdk</groupId>
diff --git a/sources/hv-collector-kafka-consumer/pom.xml b/sources/hv-collector-kafka-consumer/pom.xml
index ef09c063..c7645edf 100644
--- a/sources/hv-collector-kafka-consumer/pom.xml
+++ b/sources/hv-collector-kafka-consumer/pom.xml
@@ -74,6 +74,13 @@
       <scope>compile</scope>
     </dependency>
     <dependency>
+      <groupId>${project.parent.groupId}</groupId>
+      <artifactId>hv-collector-test-utils</artifactId>
+      <version>${project.parent.version}</version>
+      <scope>test</scope>
+    </dependency>
+
+    <dependency>
       <groupId>io.micrometer</groupId>
       <artifactId>micrometer-registry-prometheus</artifactId>
     </dependency>
@@ -91,30 +98,6 @@
       <scope>runtime</scope>
     </dependency>
     <dependency>
-      <groupId>com.nhaarman.mockitokotlin2</groupId>
-      <artifactId>mockito-kotlin</artifactId>
-      <scope>test</scope>
-    </dependency>
-    <dependency>
-      <groupId>org.jetbrains.kotlin</groupId>
-      <artifactId>kotlin-test</artifactId>
-      <scope>test</scope>
-    </dependency>
-    <dependency>
-      <groupId>org.jetbrains.spek</groupId>
-      <artifactId>spek-api</artifactId>
-      <scope>test</scope>
-    </dependency>
-    <dependency>
-      <groupId>org.jetbrains.spek</groupId>
-      <artifactId>spek-junit-platform-engine</artifactId>
-      <scope>test</scope>
-    </dependency>
-    <dependency>
-      <groupId>io.micrometer</groupId>
-      <artifactId>micrometer-registry-prometheus</artifactId>
-    </dependency>
-    <dependency>
       <groupId>io.projectreactor.netty</groupId>
       <artifactId>reactor-netty</artifactId>
     </dependency>
diff --git a/sources/hv-collector-kafka-consumer/src/main/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/metrics/Metrics.kt b/sources/hv-collector-kafka-consumer/src/main/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/metrics/Metrics.kt
index 64a7fb3e..2fabf30e 100644
--- a/sources/hv-collector-kafka-consumer/src/main/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/metrics/Metrics.kt
+++ b/sources/hv-collector-kafka-consumer/src/main/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/metrics/Metrics.kt
@@ -20,5 +20,6 @@
 package org.onap.dcae.collectors.veshv.kafkaconsumer.metrics
 
 internal interface Metrics {
-    fun notifyOffsetChanged(size: Long)
-}
+    fun notifyOffsetChanged(offset: Long)
+    fun notifyMessageTravelTime(messageSentTimeMicros: Long)
+}
\ No newline at end of file
diff --git a/sources/hv-collector-kafka-consumer/src/main/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/metrics/MicrometerMetrics.kt b/sources/hv-collector-kafka-consumer/src/main/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/metrics/MicrometerMetrics.kt
index f137d074..748e43fc 100644
--- a/sources/hv-collector-kafka-consumer/src/main/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/metrics/MicrometerMetrics.kt
+++ b/sources/hv-collector-kafka-consumer/src/main/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/metrics/MicrometerMetrics.kt
@@ -19,22 +19,40 @@
  */
 package org.onap.dcae.collectors.veshv.kafkaconsumer.metrics
 
+import io.micrometer.core.instrument.Timer
 import io.micrometer.prometheus.PrometheusConfig
 import io.micrometer.prometheus.PrometheusMeterRegistry
+import org.onap.dcae.collectors.veshv.utils.TimeUtils
 import reactor.core.publisher.Mono
+import java.time.Duration
+import java.time.Instant
+import java.util.concurrent.atomic.AtomicLong
 
 internal class MicrometerMetrics constructor(
         private val registry: PrometheusMeterRegistry = PrometheusMeterRegistry(PrometheusConfig.DEFAULT)
 ) : Metrics {
-    override fun notifyOffsetChanged(size: Long) {
-        // TODO implementation here
-    }
+
+    private val currentOffset = registry.gauge(name("consumer.offset"), AtomicLong(0))
+    private val travelTime = Timer.builder(name("travel.time"))
+            .publishPercentileHistogram(true)
+            .register(registry)
 
     fun lastStatus(): Mono<String> = Mono.fromCallable {
         registry.scrape()
     }
 
+    override fun notifyOffsetChanged(offset: Long) {
+        currentOffset.lazySet(offset)
+    }
+
+    override fun notifyMessageTravelTime(messageSentTimeMicros: Long) {
+        travelTime.record(Duration.between(TimeUtils.epochMicroToInstant(messageSentTimeMicros), Instant.now()))
+    }
+
     companion object {
         val INSTANCE by lazy { MicrometerMetrics() }
+
+        private const val PREFIX = "hv-kafka-consumer"
+        private fun name(vararg name: String) = "$PREFIX.${name.joinToString(".")}"
     }
 }
diff --git a/sources/hv-collector-kafka-consumer/src/test/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/SampleTest.kt b/sources/hv-collector-kafka-consumer/src/test/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/SampleTest.kt
deleted file mode 100644
index b7ea126f..00000000
--- a/sources/hv-collector-kafka-consumer/src/test/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/SampleTest.kt
+++ /dev/null
@@ -1,30 +0,0 @@
-/*
- * ============LICENSE_START=======================================================
- * dcaegen2-collectors-veshv
- * ================================================================================
- * Copyright (C) 2018-2019 NOKIA
- * ================================================================================
- * 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.
- * ============LICENSE_END=========================================================
- */
-package org.onap.dcae.collectors.veshv.kafkaconsumer
-
-import org.jetbrains.spek.api.Spek
-import org.jetbrains.spek.api.dsl.describe
-import kotlin.test.assertTrue
-
-object SampleTest : Spek({
-    describe("sample test") {
-        assertTrue(true)
-    }
-})
diff --git a/sources/hv-collector-kafka-consumer/src/test/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/metrics/MicrometerMetricsTest.kt b/sources/hv-collector-kafka-consumer/src/test/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/metrics/MicrometerMetricsTest.kt
new file mode 100644
index 00000000..41587867
--- /dev/null
+++ b/sources/hv-collector-kafka-consumer/src/test/kotlin/org/onap/dcae/collectors/veshv/kafkaconsumer/metrics/MicrometerMetricsTest.kt
@@ -0,0 +1,85 @@
+/*
+ * ============LICENSE_START=======================================================
+ * dcaegen2-collectors-veshv
+ * ================================================================================
+ * Copyright (C) 2019 NOKIA
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcae.collectors.veshv.kafkaconsumer.metrics
+
+import io.micrometer.prometheus.PrometheusConfig
+import io.micrometer.prometheus.PrometheusMeterRegistry
+import org.assertj.core.api.Assertions.assertThat
+import org.assertj.core.data.Percentage
+import org.jetbrains.spek.api.Spek
+import org.jetbrains.spek.api.dsl.describe
+import org.jetbrains.spek.api.dsl.it
+import org.jetbrains.spek.api.dsl.on
+import org.onap.dcae.collectors.veshv.tests.utils.verifyGauge
+import org.onap.dcae.collectors.veshv.tests.utils.verifyTimer
+import java.time.Instant
+import java.util.concurrent.TimeUnit
+
+object MicrometerMetricsTest : Spek({
+    val PREFIX = "hv-kafka-consumer"
+    val doublePrecision = Percentage.withPercentage(0.5)
+    lateinit var registry: PrometheusMeterRegistry
+    lateinit var cut: MicrometerMetrics
+
+    beforeEachTest {
+        registry = PrometheusMeterRegistry(PrometheusConfig.DEFAULT)
+        cut = MicrometerMetrics(registry)
+    }
+
+    describe("Timers") {
+        val arbitraryMessageTravelTime = 100L
+        val messageSentTimeMicros = Instant.now().minusMillis(arbitraryMessageTravelTime).toEpochMilli() * 1000
+        val timerName = "$PREFIX.travel.time"
+
+        on("notifyMessageTravelTime") {
+            it("should update timer $timerName") {
+
+                val timeBeforeNotifyMicros = Instant.now().toEpochMilli() * 1000
+                cut.notifyMessageTravelTime(messageSentTimeMicros)
+                val timeAfterNotifyMicros = Instant.now().toEpochMilli() * 1000
+
+                registry.verifyTimer(timerName) { timer ->
+                    val travelTimeBeforeNotify = (timeBeforeNotifyMicros - messageSentTimeMicros).toDouble()
+                    val travelTimeAfterNotify = (timeAfterNotifyMicros - messageSentTimeMicros).toDouble()
+                    assertThat(timer.totalTime(TimeUnit.MICROSECONDS))
+                            .isLessThanOrEqualTo(travelTimeAfterNotify)
+                            .isGreaterThanOrEqualTo(travelTimeBeforeNotify)
+
+                }
+            }
+        }
+    }
+
+    describe("Gauges") {
+        val gaugeName = "$PREFIX.consumer.offset"
+
+        on("notifyOffsetChanged") {
+            val offset = 966L
+
+            it("should update $gaugeName") {
+                cut.notifyOffsetChanged(offset)
+
+                registry.verifyGauge(gaugeName) {
+                    assertThat(it.value()).isCloseTo(offset.toDouble(), doublePrecision)
+                }
+            }
+        }
+    }
+})
diff --git a/sources/hv-collector-main/src/test/kotlin/org/onap/dcae/collectors/veshv/main/MicrometerMetricsTest.kt b/sources/hv-collector-main/src/test/kotlin/org/onap/dcae/collectors/veshv/main/MicrometerMetricsTest.kt
index f260f158..66f3a5fc 100644
--- a/sources/hv-collector-main/src/test/kotlin/org/onap/dcae/collectors/veshv/main/MicrometerMetricsTest.kt
+++ b/sources/hv-collector-main/src/test/kotlin/org/onap/dcae/collectors/veshv/main/MicrometerMetricsTest.kt
@@ -20,12 +20,10 @@
 package org.onap.dcae.collectors.veshv.main
 
 import arrow.core.Option
-import arrow.core.Try
 import io.micrometer.core.instrument.Counter
-import io.micrometer.core.instrument.Gauge
 import io.micrometer.core.instrument.Meter
+import io.micrometer.core.instrument.Tags
 import io.micrometer.core.instrument.Timer
-import io.micrometer.core.instrument.search.RequiredSearch
 import io.micrometer.prometheus.PrometheusConfig
 import io.micrometer.prometheus.PrometheusMeterRegistry
 import org.assertj.core.api.Assertions.assertThat
@@ -43,6 +41,9 @@ import org.onap.dcae.collectors.veshv.model.MessageDropCause.ROUTE_NOT_FOUND
 import org.onap.dcae.collectors.veshv.domain.RoutedMessage
 import org.onap.dcae.collectors.veshv.domain.VesMessage
 import org.onap.dcae.collectors.veshv.tests.utils.emptyWireProtocolFrame
+import org.onap.dcae.collectors.veshv.tests.utils.verifyCounter
+import org.onap.dcae.collectors.veshv.tests.utils.verifyGauge
+import org.onap.dcae.collectors.veshv.tests.utils.verifyTimer
 import org.onap.dcae.collectors.veshv.tests.utils.vesEvent
 import org.onap.dcae.collectors.veshv.tests.utils.wireProtocolFrame
 import org.onap.ves.VesEventOuterClass
@@ -65,29 +66,6 @@ object MicrometerMetricsTest : Spek({
         cut = MicrometerMetrics(registry)
     }
 
-    fun registrySearch(counterName: String) = RequiredSearch.`in`(registry).name(counterName)
-
-    fun <M, T> verifyMeter(search: RequiredSearch, map: (RequiredSearch) -> M, verifier: (M) -> T) =
-            Try {
-                map(search)
-            }.fold(
-                    { ex -> assertThat(ex).doesNotThrowAnyException() },
-                    verifier
-            )
-
-    fun <T> verifyGauge(name: String, verifier: (Gauge) -> T) =
-            verifyMeter(registrySearch(name), RequiredSearch::gauge, verifier)
-
-    fun <T> verifyTimer(name: String, verifier: (Timer) -> T) =
-            verifyMeter(registrySearch(name), RequiredSearch::timer, verifier)
-
-    fun <T> verifyCounter(search: RequiredSearch, verifier: (Counter) -> T) =
-            verifyMeter(search, RequiredSearch::counter, verifier)
-
-    fun <T> verifyCounter(name: String, verifier: (Counter) -> T) =
-            verifyCounter(registrySearch(name), verifier)
-
-
     fun verifyCountersAndTimersAreUnchangedBut(vararg changedMeters: String) {
         fun <T : Meter> verifyAllMetersAreUnchangedBut(
                 clazz: KClass<T>,
@@ -120,7 +98,7 @@ object MicrometerMetricsTest : Spek({
                 val bytes = 128
                 cut.notifyBytesReceived(bytes)
 
-                verifyCounter(counterName) {
+                registry.verifyCounter(counterName) {
                     assertThat(it.count()).isCloseTo(bytes.toDouble(), doublePrecision)
                 }
             }
@@ -139,7 +117,7 @@ object MicrometerMetricsTest : Spek({
             it("should increment counter") {
                 cut.notifyMessageReceived(emptyWireProtocolFrame())
 
-                verifyCounter(counterName) {
+                registry.verifyCounter(counterName) {
                     assertThat(it.count()).isCloseTo(1.0, doublePrecision)
                 }
             }
@@ -152,7 +130,7 @@ object MicrometerMetricsTest : Spek({
                 val bytes = 888
                 cut.notifyMessageReceived(emptyWireProtocolFrame().copy(payloadSize = bytes))
 
-                verifyCounter(counterName) {
+                registry.verifyCounter(counterName) {
                     assertThat(it.count()).isCloseTo(bytes.toDouble(), doublePrecision)
                 }
             }
@@ -177,7 +155,7 @@ object MicrometerMetricsTest : Spek({
             it("should increment counter") {
                 cut.notifyMessageSent(routedMessage(topicName1))
 
-                verifyCounter(counterName) {
+                registry.verifyCounter(counterName) {
                     assertThat(it.count()).isCloseTo(1.0, doublePrecision)
                 }
                 verifyCountersAndTimersAreUnchangedBut(
@@ -196,11 +174,11 @@ object MicrometerMetricsTest : Spek({
                 cut.notifyMessageSent(routedMessage(topicName2))
                 cut.notifyMessageSent(routedMessage(topicName2))
 
-                verifyCounter(registrySearch(counterName).tag("topic", topicName1)) {
+                registry.verifyCounter(counterName, Tags.of("topic", topicName1)) {
                     assertThat(it.count()).isCloseTo(1.0, doublePrecision)
                 }
 
-                verifyCounter(registrySearch(counterName).tag("topic", topicName2)) {
+                registry.verifyCounter(counterName, Tags.of("topic", topicName2)) {
                     assertThat(it.count()).isCloseTo(2.0, doublePrecision)
                 }
             }
@@ -214,7 +192,7 @@ object MicrometerMetricsTest : Spek({
 
                 cut.notifyMessageSent(routedMessageReceivedAt(topicName1, Instant.now().minusMillis(processingTimeMs)))
 
-                verifyTimer(counterName) { timer ->
+                registry.verifyTimer(counterName) { timer ->
                     assertThat(timer.mean(TimeUnit.MILLISECONDS)).isGreaterThanOrEqualTo(processingTimeMs.toDouble())
                 }
                 verifyCountersAndTimersAreUnchangedBut(
@@ -233,7 +211,7 @@ object MicrometerMetricsTest : Spek({
 
                 cut.notifyMessageSent(routedMessageSentAt(topicName1, Instant.now().minusMillis(latencyMs)))
 
-                verifyTimer(counterName) { timer ->
+                registry.verifyTimer(counterName) { timer ->
                     assertThat(timer.mean(TimeUnit.MILLISECONDS))
                             .isGreaterThanOrEqualTo(latencyMs.toDouble())
                             .isLessThanOrEqualTo(latencyMs + 10000.0)
@@ -256,7 +234,7 @@ object MicrometerMetricsTest : Spek({
                 cut.notifyMessageDropped(ROUTE_NOT_FOUND)
                 cut.notifyMessageDropped(INVALID_MESSAGE)
 
-                verifyCounter(counterName) {
+                registry.verifyCounter(counterName) {
                     assertThat(it.count()).isCloseTo(2.0, doublePrecision)
                 }
                 verifyCountersAndTimersAreUnchangedBut(counterName, "$PREFIX.messages.dropped.cause")
@@ -271,11 +249,11 @@ object MicrometerMetricsTest : Spek({
                 cut.notifyMessageDropped(INVALID_MESSAGE)
                 cut.notifyMessageDropped(INVALID_MESSAGE)
 
-                verifyCounter(registrySearch(counterName).tag("cause", ROUTE_NOT_FOUND.tag)) {
+                registry.verifyCounter(counterName, Tags.of("cause", ROUTE_NOT_FOUND.tag)) {
                     assertThat(it.count()).isCloseTo(1.0, doublePrecision)
                 }
 
-                verifyCounter(registrySearch(counterName).tag("cause", INVALID_MESSAGE.tag)) {
+                registry.verifyCounter(counterName, Tags.of("cause", INVALID_MESSAGE.tag)) {
                     assertThat(it.count()).isCloseTo(2.0, doublePrecision)
                 }
             }
@@ -290,7 +268,7 @@ object MicrometerMetricsTest : Spek({
                 cut.notifyClientConnected()
                 cut.notifyClientConnected()
 
-                verifyCounter(counterName) {
+                registry.verifyCounter(counterName) {
                     assertThat(it.count()).isCloseTo(2.0, doublePrecision)
                 }
                 verifyCountersAndTimersAreUnchangedBut(counterName)
@@ -307,7 +285,7 @@ object MicrometerMetricsTest : Spek({
                 cut.notifyClientDisconnected()
                 cut.notifyClientDisconnected()
 
-                verifyCounter(counterName) {
+                registry.verifyCounter(counterName) {
                     assertThat(it.count()).isCloseTo(2.0, doublePrecision)
                 }
                 verifyCountersAndTimersAreUnchangedBut(counterName)
@@ -324,7 +302,7 @@ object MicrometerMetricsTest : Spek({
                 cut.notifyClientRejected(INVALID_WIRE_FRAME_MARKER)
                 cut.notifyClientRejected(PAYLOAD_SIZE_EXCEEDED_IN_MESSAGE)
 
-                verifyCounter(counterName) {
+                registry.verifyCounter(counterName) {
                     assertThat(it.count()).isCloseTo(2.0, doublePrecision)
                 }
                 verifyCountersAndTimersAreUnchangedBut(counterName, "$PREFIX.clients.rejected.cause")
@@ -338,11 +316,11 @@ object MicrometerMetricsTest : Spek({
                 cut.notifyClientRejected(PAYLOAD_SIZE_EXCEEDED_IN_MESSAGE)
                 cut.notifyClientRejected(PAYLOAD_SIZE_EXCEEDED_IN_MESSAGE)
 
-                verifyCounter(registrySearch(counterName).tag("cause", INVALID_WIRE_FRAME_MARKER.tag)) {
+                registry.verifyCounter(counterName, Tags.of("cause", INVALID_WIRE_FRAME_MARKER.tag)) {
                     assertThat(it.count()).isCloseTo(1.0, doublePrecision)
                 }
 
-                verifyCounter(registrySearch(counterName).tag("cause", PAYLOAD_SIZE_EXCEEDED_IN_MESSAGE.tag)) {
+                registry.verifyCounter(counterName, Tags.of("cause", PAYLOAD_SIZE_EXCEEDED_IN_MESSAGE.tag)) {
                     assertThat(it.count()).isCloseTo(2.0, doublePrecision)
                 }
             }
@@ -359,7 +337,7 @@ object MicrometerMetricsTest : Spek({
                 cut.notifyClientConnected()
                 cut.notifyClientDisconnected()
 
-                verifyGauge(gaugeName) {
+                registry.verifyGauge(gaugeName) {
                     assertThat(it.value()).isCloseTo(2.0, doublePrecision)
                 }
             }
@@ -368,7 +346,7 @@ object MicrometerMetricsTest : Spek({
                 cut.notifyClientDisconnected()
                 cut.notifyClientDisconnected()
 
-                verifyGauge(gaugeName) {
+                registry.verifyGauge(gaugeName) {
                     assertThat(it.value()).isCloseTo(0.0, doublePrecision)
                 }
             }
@@ -376,7 +354,7 @@ object MicrometerMetricsTest : Spek({
             it("should calculate negative difference between connected and disconnected clients") {
                 cut.notifyClientDisconnected()
 
-                verifyGauge(gaugeName) {
+                registry.verifyGauge(gaugeName) {
                     assertThat(it.value()).isCloseTo(0.0, doublePrecision)
                 }
             }
diff --git a/sources/hv-collector-test-utils/pom.xml b/sources/hv-collector-test-utils/pom.xml
index bf70e180..97737e84 100644
--- a/sources/hv-collector-test-utils/pom.xml
+++ b/sources/hv-collector-test-utils/pom.xml
@@ -86,5 +86,10 @@
             <artifactId>logback-classic</artifactId>
             <scope>compile</scope>
         </dependency>
+        <dependency>
+            <groupId>io.micrometer</groupId>
+            <artifactId>micrometer-registry-prometheus</artifactId>
+            <scope>compile</scope>
+        </dependency>
     </dependencies>
 </project>
\ No newline at end of file
diff --git a/sources/hv-collector-test-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/tests/utils/metrics.kt b/sources/hv-collector-test-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/tests/utils/metrics.kt
new file mode 100644
index 00000000..1aefdb34
--- /dev/null
+++ b/sources/hv-collector-test-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/tests/utils/metrics.kt
@@ -0,0 +1,55 @@
+/*
+ * ============LICENSE_START=======================================================
+ * dcaegen2-collectors-veshv
+ * ================================================================================
+ * Copyright (C) 2019 NOKIA
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcae.collectors.veshv.tests.utils
+
+import arrow.core.Try
+import io.micrometer.core.instrument.Counter
+import io.micrometer.core.instrument.Gauge
+import io.micrometer.core.instrument.Tags
+import io.micrometer.core.instrument.Timer
+import io.micrometer.core.instrument.search.RequiredSearch
+import io.micrometer.prometheus.PrometheusMeterRegistry
+import org.assertj.core.api.Assertions
+
+
+fun <T> PrometheusMeterRegistry.verifyGauge(name: String, verifier: (Gauge) -> T) =
+        verifyMeter(findMeter(name), RequiredSearch::gauge, verifier)
+
+fun <T> PrometheusMeterRegistry.verifyTimer(name: String, verifier: (Timer) -> T) =
+        verifyMeter(findMeter(name), RequiredSearch::timer, verifier)
+
+fun <T> PrometheusMeterRegistry.verifyCounter(name: String, verifier: (Counter) -> T) =
+        verifyCounter(findMeter(name), verifier)
+
+fun <T> PrometheusMeterRegistry.verifyCounter(name: String, tags: Tags, verifier: (Counter) -> T) =
+        verifyCounter(findMeter(name).tags(tags), verifier)
+
+private fun PrometheusMeterRegistry.findMeter(meterName: String) = RequiredSearch.`in`(this).name(meterName)
+
+private fun <T> verifyCounter(search: RequiredSearch, verifier: (Counter) -> T) =
+        verifyMeter(search, RequiredSearch::counter, verifier)
+
+private inline fun <M, T> verifyMeter(search: RequiredSearch,
+                               map: (RequiredSearch) -> M,
+                               verifier: (M) -> T) =
+        Try { map(search) }.fold(
+                { ex -> Assertions.assertThat(ex).doesNotThrowAnyException() },
+                verifier
+        )
\ No newline at end of file