diff --git a/reader/src/main/resources/config/base.conf b/reader/src/main/resources/config/base.conf
index 628eec4e..35dc9853 100644
--- a/reader/src/main/resources/config/base.conf
+++ b/reader/src/main/resources/config/base.conf
@@ -75,8 +75,8 @@ trace {
       sequence = [
         # "com.expedia.www.haystack.trace.reader.readers.transformers.OrphanedTraceTransformer"
         "com.expedia.www.haystack.trace.reader.readers.transformers.PartialSpanTransformer"
+        "com.expedia.www.haystack.trace.reader.readers.transformers.ServerClientSpanMergeTransformer"
         "com.expedia.www.haystack.trace.reader.readers.transformers.ClockSkewTransformer"
-        "com.expedia.www.haystack.trace.reader.readers.transformers.ClockSkewFromParentTransformer"
         "com.expedia.www.haystack.trace.reader.readers.transformers.SortSpanTransformer"
       ]
     }
diff --git a/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/transformers/PartialSpanTransformer.scala b/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/transformers/PartialSpanTransformer.scala
index 1315e0ea..dfc90ed5 100644
--- a/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/transformers/PartialSpanTransformer.scala
+++ b/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/transformers/PartialSpanTransformer.scala
@@ -16,12 +16,8 @@
 
 package com.expedia.www.haystack.trace.reader.readers.transformers
 
-import com.expedia.open.tracing.{Span, Tag}
-import com.expedia.www.haystack.trace.reader.readers.utils.TagBuilders.{buildBoolTag, buildLongTag, buildStringTag}
-import com.expedia.www.haystack.trace.reader.readers.utils.TagExtractors.extractTagStringValue
-import com.expedia.www.haystack.trace.reader.readers.utils.{AuxiliaryTags, MutableSpanForest, SpanMarkers, SpanUtils}
-
-import scala.collection.JavaConverters._
+import com.expedia.open.tracing.Span
+import com.expedia.www.haystack.trace.reader.readers.utils._
 
 /**
   * Merges partial spans and generates a single Span combining a client and corresponding server span
@@ -33,106 +29,11 @@ class PartialSpanTransformer extends SpanTreeTransformer {
 
     val mergedSpans: Seq[Span] = spanForest.getUnderlyingSpans.groupBy(_.getSpanId).map((pair) => pair._2 match {
       case Seq(span: Span) => span
-      case list: Seq[Span] =>
+      case spans: Seq[Span] =>
         hasAnySpanMerged = true
-        mergeSpans(list)
+        SpanMerger.mergeSpans(spans)
     }).toSeq
 
     spanForest.updateUnderlyingSpans(mergedSpans, hasAnySpanMerged)
   }
-
-  private def mergeSpans(spans: Seq[Span]): Span = {
-    val serverSpanOptional = collapseSpans(spans.filter(SpanUtils.containsServerLogTag))
-    val clientSpanOptional = collapseSpans(spans.filter(SpanUtils.containsClientLogTag))
-
-    (clientSpanOptional, serverSpanOptional) match {
-      // ideally there should be one server and one client span
-      // merging these partial spans to form a new single span
-      case (Some(clientSpan), Some(serverSpan)) =>
-        Span
-          .newBuilder(serverSpan)
-          .setParentSpanId(clientSpan.getParentSpanId) // use the parentSpanId of the client span to stitch in the client's trace tree
-          .addAllTags((clientSpan.getTagsList.asScala ++ auxiliaryCommonTags(clientSpan, serverSpan) ++ auxiliaryClientTags(clientSpan) ++ auxiliaryServerTags(serverSpan)).asJavaCollection)
-          .clearLogs().addAllLogs((clientSpan.getLogsList.asScala ++ serverSpan.getLogsList.asScala.sortBy(_.getTimestamp)).asJavaCollection)
-          .build()
-
-      // imperfect scenario, fallback to return available server span
-      case (None, Some(serverSpan)) => serverSpan
-
-      // imperfect scenario, fallback to return available client span
-      case (Some(clientSpan), None) => clientSpan
-
-      // imperfect scenario, fallback to collapse all spans
-      case _ => collapseSpans(spans).get
-    }
-  }
-
-  // collapse all spans of a type(eg. client or server) if needed,
-  // ideally there would be just one span in the list and hence no need of collapsing
-  private def collapseSpans(spans: Seq[Span]): Option[Span] = {
-    spans match {
-      case Nil => None
-      case Seq(span) => Some(span)
-      case _ =>
-        // if there are multiple spans fallback to collapse all the spans in a single span
-        // start the collapsed span from startTime of the first and end at ending of last such span
-        // also add an error marker in the collapsed span
-        val firstSpan = spans.minBy(_.getStartTime)
-        val lastSpan = spans.maxBy(span => span.getStartTime + span.getDuration)
-        val allTags = spans.flatMap(span => span.getTagsList.asScala)
-        val allLogs = spans.flatMap(span => span.getLogsList.asScala)
-        val opName = spans.map(_.getOperationName).reduce((a, b) => a + " & " + b)
-
-        Some(
-          Span
-            .newBuilder(firstSpan)
-            .setOperationName(opName)
-            .setDuration(lastSpan.getStartTime + lastSpan.getDuration - firstSpan.getStartTime)
-            .clearTags().addAllTags(allTags.asJava)
-            .addTags(buildBoolTag(AuxiliaryTags.ERR_IS_MULTI_PARTIAL_SPAN, tagValue = true))
-            .clearLogs().addAllLogs(allLogs.asJava)
-            .build())
-    }
-  }
-
-  // Network delta - difference between server and client duration
-  // calculate only if serverDuration is smaller then client
-  private def calculateNetworkDelta(clientSpan: Span, serverSpan: Span): Option[Long] = {
-    val clientDuration = SpanUtils.getEventTimestamp(clientSpan, SpanMarkers.CLIENT_RECV_EVENT) - SpanUtils.getEventTimestamp(clientSpan, SpanMarkers.CLIENT_SEND_EVENT)
-    val serverDuration = SpanUtils.getEventTimestamp(serverSpan, SpanMarkers.SERVER_SEND_EVENT) - SpanUtils.getEventTimestamp(serverSpan, SpanMarkers.SERVER_RECV_EVENT)
-
-    // difference of duration of spans
-    if (serverDuration < clientDuration) {
-      Some(clientDuration - serverDuration)
-    } else {
-      None
-    }
-  }
-
-  private def auxiliaryCommonTags(clientSpan: Span, serverSpan: Span): List[Tag]  =
-    List(
-      buildBoolTag(AuxiliaryTags.IS_MERGED_SPAN, tagValue = true),
-      buildLongTag(AuxiliaryTags.NETWORK_DELTA, calculateNetworkDelta(clientSpan, serverSpan).getOrElse(-1))
-    )
-
-  private def auxiliaryClientTags(span: Span): List[Tag] =
-    List(
-      buildStringTag(AuxiliaryTags.CLIENT_SERVICE_NAME, span.getServiceName),
-      buildStringTag(AuxiliaryTags.CLIENT_OPERATION_NAME, span.getOperationName),
-      buildStringTag(AuxiliaryTags.CLIENT_INFRASTRUCTURE_PROVIDER, extractTagStringValue(span, AuxiliaryTags.INFRASTRUCTURE_PROVIDER)),
-      buildStringTag(AuxiliaryTags.CLIENT_INFRASTRUCTURE_LOCATION, extractTagStringValue(span, AuxiliaryTags.INFRASTRUCTURE_LOCATION)),
-      buildLongTag(AuxiliaryTags.CLIENT_START_TIME, span.getStartTime),
-      buildLongTag(AuxiliaryTags.CLIENT_DURATION, span.getDuration)
-    )
-
-  private def auxiliaryServerTags(span: Span): List[Tag] = {
-    List(
-      buildStringTag(AuxiliaryTags.SERVER_SERVICE_NAME, span.getServiceName),
-      buildStringTag(AuxiliaryTags.SERVER_OPERATION_NAME, span.getOperationName),
-      buildStringTag(AuxiliaryTags.SERVER_INFRASTRUCTURE_PROVIDER, extractTagStringValue(span, AuxiliaryTags.INFRASTRUCTURE_PROVIDER)),
-      buildStringTag(AuxiliaryTags.SERVER_INFRASTRUCTURE_LOCATION, extractTagStringValue(span, AuxiliaryTags.INFRASTRUCTURE_LOCATION)),
-      buildLongTag(AuxiliaryTags.SERVER_START_TIME, span.getStartTime),
-      buildLongTag(AuxiliaryTags.SERVER_DURATION, span.getDuration)
-    )
-  }
 }
diff --git a/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/transformers/ServerClientSpanMergeTransformer.scala b/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/transformers/ServerClientSpanMergeTransformer.scala
new file mode 100644
index 00000000..e368b8f1
--- /dev/null
+++ b/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/transformers/ServerClientSpanMergeTransformer.scala
@@ -0,0 +1,32 @@
+/*
+ *  Copyright 2018 Expedia, Inc.
+ *
+ *       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 com.expedia.www.haystack.trace.reader.readers.transformers
+
+import com.expedia.www.haystack.trace.reader.readers.utils.{MutableSpanForest, SpanMerger}
+
+class ServerClientSpanMergeTransformer extends SpanTreeTransformer {
+  override def transform(spanForest: MutableSpanForest): MutableSpanForest = {
+    spanForest.collapse((tree) =>
+      tree.children match {
+        case Seq(singleChild) if singleChild.span.getServiceName != tree.span.getServiceName && !SpanMerger.isAlreadyMergedSpan(tree.span) &&  !SpanMerger.isAlreadyMergedSpan(singleChild.span) =>
+          Some(SpanMerger.mergeParentChildSpans(tree.span, singleChild.span))
+        case _ => None
+      })
+
+    spanForest
+  }
+}
diff --git a/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/utils/SpanMerger.scala b/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/utils/SpanMerger.scala
new file mode 100644
index 00000000..f1ada41c
--- /dev/null
+++ b/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/utils/SpanMerger.scala
@@ -0,0 +1,133 @@
+/*
+ *  Copyright 2018 Expedia, Inc.
+ *
+ *       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 com.expedia.www.haystack.trace.reader.readers.utils
+
+import com.expedia.open.tracing.{Span, Tag}
+import com.expedia.www.haystack.trace.reader.readers.utils.TagBuilders.{buildBoolTag, buildLongTag, buildStringTag}
+import com.expedia.www.haystack.trace.reader.readers.utils.TagExtractors.extractTagStringValue
+
+import scala.collection.JavaConverters._
+
+object SpanMerger {
+
+  def mergeParentChildSpans(parentSpan: Span, childSpan: Span): Span = {
+    val clientSpan = if (SpanUtils.containsClientLogTag(parentSpan)) parentSpan else SpanUtils.addClientLogTag(parentSpan)
+    val serverSpan = if (SpanUtils.containsServerLogTag(childSpan)) childSpan else SpanUtils.addServerLogTag(childSpan)
+    merge(clientSpan, serverSpan)
+  }
+
+  def mergeSpans(spans: Seq[Span]): Span = {
+    val serverSpanOptional = collapseSpans(spans.filter(SpanUtils.containsServerLogTag))
+    val clientSpanOptional = collapseSpans(spans.filter(SpanUtils.containsClientLogTag))
+    (clientSpanOptional, serverSpanOptional) match {
+      // ideally there should be one server and one client span
+      // merging these partial spans to form a new single span
+      case (Some(clientSpan), Some(serverSpan)) => merge(clientSpan, serverSpan)
+
+      // imperfect scenario, fallback to return available server span
+      case (None, Some(serverSpan)) => serverSpan
+
+      // imperfect scenario, fallback to return available client span
+      case (Some(clientSpan), None) => clientSpan
+
+      // imperfect scenario, fallback to collapse all spans
+      case _ => collapseSpans(spans).get
+    }
+  }
+
+  private def merge(clientSpan: Span, serverSpan: Span): Span = {
+    Span
+      .newBuilder(serverSpan)
+      .setParentSpanId(clientSpan.getParentSpanId) // use the parentSpanId of the client span to stitch in the client's trace tree
+      .addAllTags((clientSpan.getTagsList.asScala ++ auxiliaryCommonTags(clientSpan, serverSpan) ++ auxiliaryClientTags(clientSpan) ++ auxiliaryServerTags(serverSpan)).asJavaCollection)
+      .clearLogs().addAllLogs((clientSpan.getLogsList.asScala ++ serverSpan.getLogsList.asScala.sortBy(_.getTimestamp)).asJavaCollection)
+      .build()
+  }
+
+  // collapse all spans of a type(eg. client or server) if needed,
+  // ideally there would be just one span in the list and hence no need of collapsing
+  private def collapseSpans(spans: Seq[Span]): Option[Span] = {
+    spans match {
+      case Nil => None
+      case Seq(span) => Some(span)
+      case _ =>
+        // if there are multiple spans fallback to collapse all the spans in a single span
+        // start the collapsed span from startTime of the first and end at ending of last such span
+        // also add an error marker in the collapsed span
+        val firstSpan = spans.minBy(_.getStartTime)
+        val lastSpan = spans.maxBy(span => span.getStartTime + span.getDuration)
+        val allTags = spans.flatMap(span => span.getTagsList.asScala)
+        val allLogs = spans.flatMap(span => span.getLogsList.asScala)
+        val opName = spans.map(_.getOperationName).reduce((a, b) => a + " & " + b)
+
+        Some(
+          Span
+            .newBuilder(firstSpan)
+            .setOperationName(opName)
+            .setDuration(lastSpan.getStartTime + lastSpan.getDuration - firstSpan.getStartTime)
+            .clearTags().addAllTags(allTags.asJava)
+            .addTags(buildBoolTag(AuxiliaryTags.ERR_IS_MULTI_PARTIAL_SPAN, tagValue = true))
+            .clearLogs().addAllLogs(allLogs.asJava)
+            .build())
+    }
+  }
+
+  // Network delta - difference between server and client duration
+  // calculate only if serverDuration is smaller then client
+  private def calculateNetworkDelta(clientSpan: Span, serverSpan: Span): Option[Long] = {
+    val clientDuration = SpanUtils.getEventTimestamp(clientSpan, SpanMarkers.CLIENT_RECV_EVENT) - SpanUtils.getEventTimestamp(clientSpan, SpanMarkers.CLIENT_SEND_EVENT)
+    val serverDuration = SpanUtils.getEventTimestamp(serverSpan, SpanMarkers.SERVER_SEND_EVENT) - SpanUtils.getEventTimestamp(serverSpan, SpanMarkers.SERVER_RECV_EVENT)
+
+    // difference of duration of spans
+    if (serverDuration < clientDuration) {
+      Some(clientDuration - serverDuration)
+    } else {
+      None
+    }
+  }
+
+  private def auxiliaryCommonTags(clientSpan: Span, serverSpan: Span): List[Tag]  =
+    List(
+      buildBoolTag(AuxiliaryTags.IS_MERGED_SPAN, tagValue = true),
+      buildLongTag(AuxiliaryTags.NETWORK_DELTA, calculateNetworkDelta(clientSpan, serverSpan).getOrElse(-1))
+    )
+
+  private def auxiliaryClientTags(span: Span): List[Tag] =
+    List(
+      buildStringTag(AuxiliaryTags.CLIENT_SERVICE_NAME, span.getServiceName),
+      buildStringTag(AuxiliaryTags.CLIENT_OPERATION_NAME, span.getOperationName),
+      buildStringTag(AuxiliaryTags.CLIENT_INFRASTRUCTURE_PROVIDER, extractTagStringValue(span, AuxiliaryTags.INFRASTRUCTURE_PROVIDER)),
+      buildStringTag(AuxiliaryTags.CLIENT_INFRASTRUCTURE_LOCATION, extractTagStringValue(span, AuxiliaryTags.INFRASTRUCTURE_LOCATION)),
+      buildLongTag(AuxiliaryTags.CLIENT_START_TIME, span.getStartTime),
+      buildLongTag(AuxiliaryTags.CLIENT_DURATION, span.getDuration)
+    )
+
+  private def auxiliaryServerTags(span: Span): List[Tag] = {
+    List(
+      buildStringTag(AuxiliaryTags.SERVER_SERVICE_NAME, span.getServiceName),
+      buildStringTag(AuxiliaryTags.SERVER_OPERATION_NAME, span.getOperationName),
+      buildStringTag(AuxiliaryTags.SERVER_INFRASTRUCTURE_PROVIDER, extractTagStringValue(span, AuxiliaryTags.INFRASTRUCTURE_PROVIDER)),
+      buildStringTag(AuxiliaryTags.SERVER_INFRASTRUCTURE_LOCATION, extractTagStringValue(span, AuxiliaryTags.INFRASTRUCTURE_LOCATION)),
+      buildLongTag(AuxiliaryTags.SERVER_START_TIME, span.getStartTime),
+      buildLongTag(AuxiliaryTags.SERVER_DURATION, span.getDuration)
+    )
+  }
+
+  def isAlreadyMergedSpan(span: Span): Boolean = {
+    span.getTagsList.asScala.exists(tag => tag.getKey.equals(AuxiliaryTags.IS_MERGED_SPAN))
+  }
+}
diff --git a/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/utils/SpanTree.scala b/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/utils/SpanTree.scala
index 2beb3ce9..d537d97f 100644
--- a/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/utils/SpanTree.scala
+++ b/reader/src/main/scala/com/expedia/www/haystack/trace/reader/readers/utils/SpanTree.scala
@@ -128,6 +128,33 @@ case class MutableSpanForest(private var spans: Seq[Span]) {
       })
     }
   }
+
+  def collapse(applyCondition: (SpanTree) => Option[Span]): Unit = {
+    val underlyingSpans = mutable.ListBuffer[Span]()
+
+    def collapseTree(spanTree: SpanTree): Unit = {
+      val queue = mutable.Queue[SpanTree]()
+      queue.enqueue(spanTree)
+
+      while (queue.nonEmpty) {
+        val tree = queue.dequeue()
+        applyCondition(tree) match {
+          case Some(mergedSpan) =>
+            tree.span = mergedSpan
+            val childSpanTrees = new ListBuffer[SpanTree]()
+            tree.children.foreach(t => childSpanTrees.appendAll(t.children))
+            tree.children.clear()
+            childSpanTrees.foreach(tr => tree.children.append(tr))
+          case _ =>
+        }
+        underlyingSpans.append(tree.span)
+        queue.enqueue(tree.children:_*)
+      }
+    }
+
+    getAllTrees.foreach(collapseTree)
+    updateUnderlyingSpans(underlyingSpans, triggerForestUpdate = false)
+  }
 }
 
 case class SpanTree(var span: Span, children: mutable.ListBuffer[SpanTree] = mutable.ListBuffer[SpanTree]())
diff --git a/reader/src/test/scala/com/expedia/www/haystack/trace/reader/unit/readers/transformers/ServerClientSpanMergeTransformerSpec.scala b/reader/src/test/scala/com/expedia/www/haystack/trace/reader/unit/readers/transformers/ServerClientSpanMergeTransformerSpec.scala
new file mode 100644
index 00000000..1fa8e4bc
--- /dev/null
+++ b/reader/src/test/scala/com/expedia/www/haystack/trace/reader/unit/readers/transformers/ServerClientSpanMergeTransformerSpec.scala
@@ -0,0 +1,145 @@
+/*
+ *  Copyright 2018 Expedia, Inc.
+ *
+ *       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 com.expedia.www.haystack.trace.reader.unit.readers.transformers
+
+
+import com.expedia.open.tracing.Span
+import com.expedia.www.haystack.trace.reader.readers.transformers.ServerClientSpanMergeTransformer
+import com.expedia.www.haystack.trace.reader.readers.utils.{AuxiliaryTags, MutableSpanForest, SpanMarkers}
+import com.expedia.www.haystack.trace.reader.unit.BaseUnitTestSpec
+import com.expedia.www.haystack.trace.reader.unit.readers.builders.ValidTraceBuilder
+
+import scala.collection.JavaConverters._
+
+class ServerClientSpanMergeTransformerSpec extends BaseUnitTestSpec with ValidTraceBuilder {
+
+  private def createSpansWithClientAndServer() = {
+    val traceId = "traceId"
+
+    val timestamp = System.currentTimeMillis() * 1000
+
+    val serverSpanA = Span.newBuilder()
+      .setSpanId("sa")
+      .setTraceId(traceId)
+      .setServiceName("aSvc")
+      .setStartTime(timestamp + 100)
+      .setDuration(1000)
+      .build()
+
+    val clientSpanA = Span.newBuilder()
+      .setSpanId("ca")
+      .setParentSpanId("sa")
+      .setTraceId(traceId)
+      .setServiceName("aSvc")
+      .setStartTime(timestamp + 100)
+      .setDuration(1000)
+      .build()
+
+    val serverSpanB = Span.newBuilder()
+      .setSpanId("sb")
+      .setParentSpanId("ca")
+      .setServiceName("bSvc")
+      .setTraceId(traceId)
+      .setStartTime(timestamp + 200)
+      .setDuration(100)
+      .build()
+
+    val clientSpanB_1 = Span.newBuilder()
+      .setSpanId("cb1")
+      .setParentSpanId("sb")
+      .setServiceName("bSvc")
+      .setTraceId(traceId)
+      .setStartTime(timestamp + 300)
+      .setDuration(100)
+      .build()
+
+    val clientSpanB_2 = Span.newBuilder()
+      .setSpanId("cb2")
+      .setParentSpanId("sb")
+      .setServiceName("bSvc")
+      .setStartTime(timestamp + 400)
+      .setTraceId(traceId)
+      .setDuration(100)
+      .build()
+
+    val serverSpanC_1 = Span.newBuilder()
+      .setSpanId("sc1")
+      .setParentSpanId("cb1")
+      .setServiceName("cSvc")
+      .setTraceId(traceId)
+      .setStartTime(timestamp + 500)
+      .setDuration(100)
+      .build()
+
+    val serverSpanC_2 = Span.newBuilder()
+      .setSpanId("sc2")
+      .setParentSpanId("cb2")
+      .setServiceName("cSvc")
+      .setTraceId(traceId)
+      .setStartTime(timestamp + 600)
+      .setDuration(100)
+      .build()
+
+    List(serverSpanA, clientSpanA, serverSpanB, clientSpanB_1, clientSpanB_2, serverSpanC_1, serverSpanC_2)
+  }
+
+  describe("ServerClientSpanMergeTransformer") {
+    it("should merge the server client spans") {
+      Given("a sequence of spans of a given trace")
+      val spans = createSpansWithClientAndServer()
+
+      When("invoking transform")
+      val mergedSpans =
+        new ServerClientSpanMergeTransformer().transform(MutableSpanForest(spans))
+
+      val underlyingSpans = mergedSpans.getUnderlyingSpans
+
+      Then("return partial spans merged with server span being primary")
+      underlyingSpans.length should be(4)
+      underlyingSpans.foreach(span => span.getTraceId shouldBe traceId)
+      underlyingSpans.head.getSpanId shouldBe "sa"
+      underlyingSpans.head.getParentSpanId shouldBe ""
+
+      underlyingSpans.apply(1).getSpanId shouldBe "sb"
+      underlyingSpans.apply(1).getParentSpanId shouldBe "sa"
+      underlyingSpans.apply(1).getServiceName shouldBe "bSvc"
+      underlyingSpans.apply(1).getTagsList.asScala.find(tag => tag.getKey.equals(AuxiliaryTags.IS_MERGED_SPAN)).get.getVBool shouldBe true
+      underlyingSpans.apply(1).getLogsCount shouldBe 4
+
+      underlyingSpans.apply(2).getSpanId shouldBe "sc1"
+      underlyingSpans.apply(2).getParentSpanId shouldBe "sb"
+      underlyingSpans.apply(2).getServiceName shouldBe "cSvc"
+      underlyingSpans.apply(2).getTagsList.asScala.find(tag => tag.getKey.equals(AuxiliaryTags.IS_MERGED_SPAN)).get.getVBool shouldBe true
+      underlyingSpans.apply(2).getLogsCount shouldBe 4
+
+      underlyingSpans.apply(3).getSpanId shouldBe "sc2"
+      underlyingSpans.apply(3).getParentSpanId shouldBe "sb"
+      underlyingSpans.apply(3).getServiceName shouldBe "cSvc"
+      underlyingSpans.apply(3).getTagsList.asScala.find(tag => tag.getKey.equals(AuxiliaryTags.IS_MERGED_SPAN)).get.getVBool shouldBe true
+      underlyingSpans.apply(3).getLogsCount shouldBe 4
+
+      mergedSpans.countTrees shouldBe 1
+      val spanTree = mergedSpans.getAllTrees.head
+      spanTree.span shouldBe underlyingSpans.head
+      spanTree.children.size shouldBe 1
+      spanTree.children.head.children.size shouldBe 2
+      spanTree.children.head.span shouldBe underlyingSpans.apply(1)
+      spanTree.children.head.children.map(_.span) should contain allOf(underlyingSpans.apply(2), underlyingSpans.apply(3))
+      spanTree.children.head.children.foreach(tree => tree.children.size shouldBe 0)
+    }
+  }
+}
\ No newline at end of file