diff --git a/cassovary-core/src/main/scala/com/twitter/cassovary/graph/TestGraph.scala b/cassovary-core/src/main/scala/com/twitter/cassovary/graph/TestGraph.scala
index 7417ddf0..2987d83d 100644
--- a/cassovary-core/src/main/scala/com/twitter/cassovary/graph/TestGraph.scala
+++ b/cassovary-core/src/main/scala/com/twitter/cassovary/graph/TestGraph.scala
@@ -15,9 +15,10 @@ package com.twitter.cassovary.graph
 
 import com.twitter.cassovary.graph.StoredGraphDir._
 import com.twitter.cassovary.util.{Sampling, BinomialDistribution}
+import java.util.concurrent.ConcurrentLinkedQueue
 import scala.collection.mutable
+import scala.collection.JavaConverters._
 import scala.util.Random
-import scala.collection.mutable.ArrayBuffer
 
 /**
  * A simple implementation of a DirectedGraph
@@ -155,8 +156,8 @@ object TestGraphs {
    */
   def generateRandomUndirectedGraph(numNodes: Int, probEdge: Double,
                                     graphDir: StoredGraphDir = StoredGraphDir.BothInOut) = {
-    val nodes = Array.fill[mutable.Buffer[Int]](numNodes){new ArrayBuffer[Int]() with mutable.SynchronizedBuffer[Int]}
-    def addMutualEdge(i: Int)(j: Int) {nodes(i) += j; nodes(j) += i}
+    val nodes = Array.fill(numNodes){new ConcurrentLinkedQueue[Int]()}
+    def addMutualEdge(i: Int)(j: Int) {nodes(i).add(j); nodes(j).add(i)}
     val rand = new Random
     val binomialDistribution = new BinomialDistribution(numNodes - 1, probEdge)
     // Sampling edges only from nodes with lower id to higher id. In order to
@@ -176,7 +177,7 @@ object TestGraphs {
           higherNodeNeighbors map (higherNode + _ + 1) foreach addMutualEdge(higherNode)
     }
     val nodesEdges = nodes.indices map { i =>
-      NodeIdEdgesMaxId(i, nodes(i).toArray)
+      NodeIdEdgesMaxId(i, nodes(i).asScala.toArray)
     }
     ArrayBasedDirectedGraph( () => nodesEdges.iterator, graphDir)
   }
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/algorithms/PageRankSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/algorithms/PageRankSpec.scala
index 6b0303b0..9af9d4f0 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/algorithms/PageRankSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/algorithms/PageRankSpec.scala
@@ -14,10 +14,10 @@
 package com.twitter.cassovary.algorithms
 
 import com.twitter.cassovary.graph.TestGraphs
-import org.scalatest.matchers._
-import org.scalatest.WordSpec
+import org.scalatest.{Matchers, WordSpec}
+import org.scalatest.matchers.{Matcher, MatchResult}
 
-class PageRankSpec extends WordSpec with ShouldMatchers {
+class PageRankSpec extends WordSpec with Matchers {
 
   val EPSILON = 1e-6
 
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/algorithms/TriangleCountSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/algorithms/TriangleCountSpec.scala
index a7554342..1632fbc5 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/algorithms/TriangleCountSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/algorithms/TriangleCountSpec.scala
@@ -14,10 +14,9 @@
 package com.twitter.cassovary.algorithms
 
 import com.twitter.cassovary.graph.TestGraphs
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 
-class TriangleCountSpec extends WordSpec with ShouldMatchers {
+class TriangleCountSpec extends WordSpec with Matchers {
 
   def averageOfPairs(f: => (Double, Double), repetitions: Int): (Double, Double) = {
     val sums = (0 until repetitions).map(_ => f).reduce((p1, p2) => (p1._1 + p2._1, p1._2 + p2._2))
@@ -47,9 +46,9 @@ class TriangleCountSpec extends WordSpec with ShouldMatchers {
       val graph = TestGraphs.generateRandomUndirectedGraph(numberOfNodes, 2.0 / numberOfNodes)
       val pars = TriangleCountParameters(200, 200)
       val (transitivity, triangles) = TriangleCount(graph, pars)
-      transitivity should be(0.0 plusOrMinus 0.05)
+      transitivity should be(0.0 +- 0.05)
 
-      triangles should be(0.0 plusOrMinus 20.0)
+      triangles should be(0.0 +- 20.0)
     }
 
 
@@ -59,13 +58,13 @@ class TriangleCountSpec extends WordSpec with ShouldMatchers {
       val erGraph = TestGraphs.generateRandomUndirectedGraph(numberOfNodes, edgeProbability)
       val pars = TriangleCountParameters(500, 500)
       val (transitivity, triangles) = averageOfPairs(TriangleCount(erGraph, pars), 10)
-      transitivity should be(edgeProbability plusOrMinus 0.15 * edgeProbability)
+      transitivity should be(edgeProbability +- (0.15 * edgeProbability))
 
       def averageTrianglesInERGraph(nodes: Int, p: Double) = {
         p * p * p * nodes * (nodes - 1) * (nodes - 2) / 6
       }
       val expectedTriangles = averageTrianglesInERGraph(numberOfNodes, edgeProbability)
-      triangles should be(expectedTriangles plusOrMinus (0.3 * expectedTriangles))
+      triangles should be (expectedTriangles +- (0.3 * expectedTriangles))
     }
 
     "Return correct results for complete graph" in {
@@ -73,14 +72,14 @@ class TriangleCountSpec extends WordSpec with ShouldMatchers {
       val graph = TestGraphs.generateCompleteGraph(nodes)
       val pars = TriangleCountParameters(1000, 1000)
       val (transitivity, triangles) = averageOfPairs(TriangleCount(graph, pars), 5)
-      transitivity should be(1.0 plusOrMinus 0.1)
+      transitivity should be(1.0 +- 0.1)
 
       def trianglesInCompleteGraph(nodes: Int): Double = {
         (nodes * (nodes - 1) * (nodes - 2)) / 6
       }
 
       val expectedTriangles = trianglesInCompleteGraph(nodes)
-      triangles should be(expectedTriangles plusOrMinus (0.25 * expectedTriangles))
+      triangles should be(expectedTriangles +- (0.25 * expectedTriangles))
     }
   }
 }
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedGraphSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedGraphSpec.scala
index 971d634a..0ec5dedd 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedGraphSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedGraphSpec.scala
@@ -14,12 +14,11 @@
 package com.twitter.cassovary.graph
 
 import org.junit.runner.RunWith
-import org.scalatest.WordSpec
+import org.scalatest.{Matchers, WordSpec}
 import org.scalatest.junit.JUnitRunner
-import org.scalatest.matchers.ShouldMatchers
 
 @RunWith(classOf[JUnitRunner])
-class DirectedGraphSpec extends WordSpec with ShouldMatchers {
+class DirectedGraphSpec extends WordSpec with Matchers {
 
   val twoNodeGraph = TestGraphs.g2_mutual
   val sixNodeGraph = TestGraphs.g6
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedGraphUtilsSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedGraphUtilsSpec.scala
index 4115c125..983d0e4a 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedGraphUtilsSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedGraphUtilsSpec.scala
@@ -14,12 +14,11 @@
 package com.twitter.cassovary.graph
 
 import org.junit.runner.RunWith
-import org.scalatest.WordSpec
+import org.scalatest.{Matchers, WordSpec}
 import org.scalatest.junit.JUnitRunner
-import org.scalatest.matchers.ShouldMatchers
 
 @RunWith(classOf[JUnitRunner])
-class DirectedGraphUtilsSpec extends WordSpec with ShouldMatchers {
+class DirectedGraphUtilsSpec extends WordSpec with Matchers {
 
   private def utils(graph: DirectedGraph) = {
     (graph, new DirectedGraphUtils(graph))
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedPathCollectionSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedPathCollectionSpec.scala
index 7ce55b22..044132ca 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedPathCollectionSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedPathCollectionSpec.scala
@@ -16,12 +16,11 @@ package com.twitter.cassovary.graph
 import com.twitter.cassovary.util.FastUtilUtils
 import it.unimi.dsi.fastutil.objects.Object2IntMap
 import org.junit.runner.RunWith
-import org.scalatest.WordSpec
+import org.scalatest.{Matchers, WordSpec}
 import org.scalatest.junit.JUnitRunner
-import org.scalatest.matchers.ShouldMatchers
 
 @RunWith(classOf[JUnitRunner])
-class DirectedPathCollectionSpec extends WordSpec with ShouldMatchers {
+class DirectedPathCollectionSpec extends WordSpec with Matchers {
 
 
   "DirectedPathCollection" when {
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedPathSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedPathSpec.scala
index c5ed22c9..671b47e9 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedPathSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/DirectedPathSpec.scala
@@ -13,10 +13,9 @@
  */
 package com.twitter.cassovary.graph
 
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 
-class DirectedPathSpec extends WordSpec with ShouldMatchers  {
+class DirectedPathSpec extends WordSpec with Matchers  {
 
   "path of many nodes" should {
     "length, append, exists, equals" in {
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/GraphBehaviours.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/GraphBehaviours.scala
index 5929961c..d1d86b85 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/GraphBehaviours.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/GraphBehaviours.scala
@@ -14,10 +14,9 @@ package com.twitter.cassovary.graph
 
 import com.twitter.cassovary.graph.StoredGraphDir._
 import com.twitter.cassovary.util.NodeNumberer
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 
-trait GraphBehaviours extends ShouldMatchers {
+trait GraphBehaviours extends Matchers {
   this: WordSpec =>
 
   private def correctNumberOfNodesAndEdges(graph: DirectedGraph, numNodes: Int) {
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/GraphUtilsSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/GraphUtilsSpec.scala
index bf095109..1de5c5a1 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/GraphUtilsSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/GraphUtilsSpec.scala
@@ -19,11 +19,10 @@ import com.twitter.util.Duration
 import com.twitter.util.Stopwatch
 import it.unimi.dsi.fastutil.ints.Int2IntMap
 import it.unimi.dsi.fastutil.objects.Object2IntMap
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 
 // TODO add a fake random so that the random walk tests can be controlled
-class GraphUtilsSpec extends WordSpec with ShouldMatchers {
+class GraphUtilsSpec extends WordSpec with Matchers {
 
   def utils(graph: DirectedGraph) = {
     (graph, new GraphUtils(graph))
@@ -185,7 +184,7 @@ class GraphUtilsSpec extends WordSpec with ShouldMatchers {
         val walk = graphUtils.randomWalk(OutDir, Seq(startNodeId), walkParams)
         val duration: Duration = elapsed()
         val (visitsCounter, _) = walk
-        visitsCounter.infoAllNodes.size should be > (graph.getNodeById(startNodeId).get.outboundCount)
+        visitsCounter.infoAllNodes.size should be > graph.getNodeById(startNodeId).get.outboundCount
         if (times > ignoreFirstNum) {
           sumDuration += duration.inMilliseconds
         }
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/NodeSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/NodeSpec.scala
index 5b5b1561..7f12c4df 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/NodeSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/NodeSpec.scala
@@ -13,10 +13,9 @@
  */
 package com.twitter.cassovary.graph
 
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 
-class NodeSpec extends WordSpec with ShouldMatchers {
+class NodeSpec extends WordSpec with Matchers {
 
   def noInboundOrOutboundEdges = TestNode(1, Nil, Nil)
   def onlyInboundEdges = TestNode(1, List(2), Nil)
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/NodeUtilsSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/NodeUtilsSpec.scala
index 4bc117eb..5fbb6855 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/NodeUtilsSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/NodeUtilsSpec.scala
@@ -14,10 +14,9 @@
 package com.twitter.cassovary.graph
 
 import com.twitter.cassovary.graph.GraphDir._
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 
-class NodeUtilsSpec extends WordSpec with ShouldMatchers  {
+class NodeUtilsSpec extends WordSpec with Matchers  {
 
   def fixture = TestNode(100, List(1,2,3), List(60, 70))
 
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/SynchronizedDynamicGraphSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/SynchronizedDynamicGraphSpec.scala
index e65f7404..c47128cc 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/SynchronizedDynamicGraphSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/SynchronizedDynamicGraphSpec.scala
@@ -14,13 +14,12 @@
 package com.twitter.cassovary.graph
 
 import java.util.concurrent.Executors
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 import StoredGraphDir._
 import scala.concurrent.{Await, ExecutionContext, Future}
 import scala.concurrent.duration.Duration
 
-class SynchronizedDynamicGraphSpec extends WordSpec with ShouldMatchers {
+class SynchronizedDynamicGraphSpec extends WordSpec with Matchers {
   implicit val ecctxt = ExecutionContext.fromExecutorService(Executors.newFixedThreadPool(4))
 
   "Add new nodes" in {
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/TestGraphSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/TestGraphSpec.scala
index c3178283..b5526c65 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/TestGraphSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/TestGraphSpec.scala
@@ -13,12 +13,11 @@
 
 package com.twitter.cassovary.graph
 import org.junit.runner.RunWith
-import org.scalatest.WordSpec
+import org.scalatest.{Matchers, WordSpec}
 import org.scalatest.junit.JUnitRunner
-import org.scalatest.matchers.ShouldMatchers
 
 @RunWith(classOf[JUnitRunner])
-class TestGraphSpec extends WordSpec with ShouldMatchers with GraphBehaviours {
+class TestGraphSpec extends WordSpec with Matchers with GraphBehaviours {
 
   "three node graph g3 stored in both directions" should {
     val graph = TestGraphs.g3
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/TraverserSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/TraverserSpec.scala
index 5d961828..bcf303b1 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/TraverserSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/TraverserSpec.scala
@@ -14,13 +14,12 @@
 package com.twitter.cassovary.graph
 
 import org.mockito.Mockito._
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 import org.scalatest.mock.MockitoSugar
 
 import scala.util.Random
 
-class TraverserSpec extends WordSpec with MockitoSugar with ShouldMatchers {
+class TraverserSpec extends WordSpec with MockitoSugar with Matchers {
 
   class TestIter extends Iterator[Int] {
     var i = 0
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/bipartite/BipartiteGraphSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/bipartite/BipartiteGraphSpec.scala
index 985a5ef3..7ccfb479 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/bipartite/BipartiteGraphSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/bipartite/BipartiteGraphSpec.scala
@@ -14,11 +14,10 @@
 package com.twitter.cassovary.graph.bipartite
 
 import com.twitter.cassovary.graph.GraphDir
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 import scala.collection.mutable
 
-class BipartiteGraphSpec extends WordSpec with ShouldMatchers {
+class BipartiteGraphSpec extends WordSpec with Matchers {
 
   def bipartiteExampleSingleSide() = {
    /*
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/NodeBehaviors.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/NodeBehaviors.scala
index 895fe1e5..a867e14b 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/NodeBehaviors.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/NodeBehaviors.scala
@@ -14,10 +14,9 @@ package com.twitter.cassovary.graph.node
 
 import NodeTestUtils._
 import com.twitter.cassovary.graph.Node
-import org.scalatest.matchers.ShouldMatchers
-import org.scalatest.WordSpec
+import org.scalatest.{Matchers, WordSpec}
 
-trait NodeBehaviors extends WordSpec with ShouldMatchers {
+trait NodeBehaviors extends WordSpec with Matchers {
   val nodeId = 100
   val neighbors = Array(1,2,3)
   val inEdges = Array(4,5)
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/NodeTestUtils.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/NodeTestUtils.scala
index 8ee102ec..e34eba0e 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/NodeTestUtils.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/NodeTestUtils.scala
@@ -14,8 +14,7 @@
 
 package com.twitter.cassovary.graph.node
 
-import com.twitter.cassovary.graph.StoredGraphDir._
-import com.twitter.cassovary.graph.{Node, StoredGraphDir}
+import com.twitter.cassovary.graph.Node
 import org.scalatest.matchers.{MatchResult, Matcher}
 
 object NodeTestUtils {
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/SharedArrayBasedDirectedNodeSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/SharedArrayBasedDirectedNodeSpec.scala
index a07cb133..f7ceddd7 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/SharedArrayBasedDirectedNodeSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/SharedArrayBasedDirectedNodeSpec.scala
@@ -13,7 +13,7 @@
  */
 package com.twitter.cassovary.graph.node
 
-import com.twitter.cassovary.graph.{Node, StoredGraphDir}
+import com.twitter.cassovary.graph.StoredGraphDir
 
 class SharedArrayBasedDirectedNodeSpec extends NodeBehaviors {
   val sharedArray = Array[Array[Int]](neighbors)
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/SynchronizedDynamicNodeSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/SynchronizedDynamicNodeSpec.scala
index 0be36cb5..992ff900 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/SynchronizedDynamicNodeSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/node/SynchronizedDynamicNodeSpec.scala
@@ -13,10 +13,9 @@
  */
 package com.twitter.cassovary.graph.node
 
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 
-class SynchronizedDynamicNodeSpec extends WordSpec with ShouldMatchers {
+class SynchronizedDynamicNodeSpec extends WordSpec with Matchers {
 
   def fixture(id: Int) = new SynchronizedDynamicNode(id)
 
@@ -27,7 +26,7 @@ class SynchronizedDynamicNodeSpec extends WordSpec with ShouldMatchers {
       node1.addInBoundNode(2)
       val node3 = fixture(2)
       node1 shouldEqual node2
-      node1 should not equal (node3)
+      node1 should not equal node3
     }
 
     "perform add/delete functions correctly" in {
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/tourist/NodeTouristSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/tourist/NodeTouristSpec.scala
index 95719ade..4ccdbb2e 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/graph/tourist/NodeTouristSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/graph/tourist/NodeTouristSpec.scala
@@ -17,10 +17,9 @@ import com.twitter.cassovary.graph.{DirectedPath, TestNode}
 import com.twitter.cassovary.util.FastUtilUtils
 import it.unimi.dsi.fastutil.ints.Int2IntMap
 import it.unimi.dsi.fastutil.objects.Object2IntMap
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 
-class NodeTouristSpec extends WordSpec with ShouldMatchers {
+class NodeTouristSpec extends WordSpec with Matchers {
 
   def testNode(id: Int) = TestNode(id, Nil, Nil)
 
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/util/BinomialDistributionSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/util/BinomialDistributionSpec.scala
index 2bad2232..6ccb4220 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/util/BinomialDistributionSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/util/BinomialDistributionSpec.scala
@@ -15,12 +15,11 @@ package com.twitter.cassovary.util
 
 import org.junit.runner.RunWith
 import org.scalatest.junit.JUnitRunner
-import org.scalatest.matchers.ShouldMatchers
-import org.scalatest.{PrivateMethodTester, WordSpec}
+import org.scalatest.{Matchers, PrivateMethodTester, WordSpec}
 import scala.util.Random
 
 @RunWith(classOf[JUnitRunner])
-class BinomialDistributionSpec extends WordSpec with ShouldMatchers with PrivateMethodTester {
+class BinomialDistributionSpec extends WordSpec with Matchers with PrivateMethodTester {
   val twoPoint = new BinomialDistribution(1, 0.3)
 
   val twoTrials = new BinomialDistribution(2, 0.8)
@@ -45,12 +44,12 @@ class BinomialDistributionSpec extends WordSpec with ShouldMatchers with Private
   "binomial distribution with 2 trials" should {
     val expected = Array(0.2 * 0.2, 2 * 0.2 * 0.8, 0.8 * 0.8)
     "have correct pdf" in {
-      (twoTrials invokePrivate pdf()).zip(expected).foreach{case (x, y) => x should be (y plusOrMinus 0.001)}
+      (twoTrials invokePrivate pdf()).zip(expected).foreach{case (x, y) => x should be (y +- 0.001)}
     }
 
     "have correct cdf" in {
       val expected = Array(0.2 * 0.2, 0.2 * 0.2 + 2 * 0.2 * 0.8)
-      (twoTrials invokePrivate cdf()).zip(expected).foreach{case (x, y) => x should be (y plusOrMinus 0.001)}
+      (twoTrials invokePrivate cdf()).zip(expected).foreach{case (x, y) => x should be (y +- 0.001)}
     }
   }
 
@@ -80,7 +79,7 @@ class BinomialDistributionSpec extends WordSpec with ShouldMatchers with Private
     }
 
     "have pdf that sums up to 1" in {
-      (distribution10 invokePrivate pdf()).sum should be (1.0 plusOrMinus 0.005)
+      (distribution10 invokePrivate pdf()).sum should be (1.0 +- 0.005)
     }
 
     "have increasing cdf" in {
@@ -100,7 +99,7 @@ class BinomialDistributionSpec extends WordSpec with ShouldMatchers with Private
         val error = (distribution10 invokePrivate pdf())(i) - histogram.getOrElse(i, 0.0)
         mse += error * error
       }
-      mse should be (0.0 plusOrMinus 0.01) // checked experimentally to be true with high probability
+      mse should be (0.0 +- 0.01) // checked experimentally to be true with high probability
     }
   }
 }
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/util/MapNodeNumbererSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/util/MapNodeNumbererSpec.scala
index d308b24c..90838f9f 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/util/MapNodeNumbererSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/util/MapNodeNumbererSpec.scala
@@ -16,11 +16,10 @@ package com.twitter.cassovary.util
 
 import org.junit.runner.RunWith
 import org.scalatest.junit.JUnitRunner
-import org.scalatest.WordSpec
-import org.scalatest.matchers.{ShouldMatchers}
+import org.scalatest.{Matchers, WordSpec}
 
 @RunWith(classOf[JUnitRunner])
-class MapNodeNumbererSpec extends WordSpec with ShouldMatchers {
+class MapNodeNumbererSpec extends WordSpec with Matchers {
   val directory = "cassovary-core/src/test/resources/nodeNumberers/"
 
   "Map node numberer" should {
@@ -36,19 +35,17 @@ class MapNodeNumbererSpec extends WordSpec with ShouldMatchers {
       numberer.internalToExternal(29) should be ("spoon")
       numberer.internalToExternal(12) should be ("bike")
 
-      evaluating (numberer.externalToInternal("apple")) should produce [NoSuchElementException]
+      an [NoSuchElementException] should be thrownBy numberer.externalToInternal("apple")
 
-      evaluating (numberer.internalToExternal(3)) should produce [NoSuchElementException]
+      an [NoSuchElementException] should be thrownBy numberer.internalToExternal(3)
     }
 
     "find duplicated names" in {
-      evaluating (MapNodeNumberer.forStringsFromFile(directory + "numbering-duplicatedId.txt")) should
-        produce [Exception]
+      an [Exception] should be thrownBy MapNodeNumberer.forStringsFromFile(directory + "numbering-duplicatedId.txt")
     }
 
     "find duplicated ids" in {
-      evaluating (MapNodeNumberer.forStringsFromFile(directory + "numbering-duplicatedName.txt")) should
-        produce [Exception]
+      an [Exception] should be thrownBy MapNodeNumberer.forStringsFromFile(directory + "numbering-duplicatedName.txt")
     }
   }
 }
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/util/SamplingSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/util/SamplingSpec.scala
index c5df6530..2f99a3fa 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/util/SamplingSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/util/SamplingSpec.scala
@@ -15,12 +15,11 @@ package com.twitter.cassovary.util
 
 import org.junit.runner.RunWith
 import org.scalatest.junit.JUnitRunner
-import org.scalatest.matchers.ShouldMatchers
-import org.scalatest.WordSpec
+import org.scalatest.{Matchers, WordSpec}
 import scala.util.Random
 
 @RunWith(classOf[JUnitRunner])
-class SamplingSpec extends WordSpec with ShouldMatchers {
+class SamplingSpec extends WordSpec with Matchers {
   val array = (1 to 100).toArray
   val range =  1 to 100
 
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/util/SequentialNodeNumbererSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/util/SequentialNodeNumbererSpec.scala
index f891f7c6..5e2f8916 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/util/SequentialNodeNumbererSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/util/SequentialNodeNumbererSpec.scala
@@ -14,13 +14,12 @@
 package com.twitter.cassovary.util
 
 import org.junit.runner.RunWith
-import org.scalatest.WordSpec
+import org.scalatest.{Matchers, WordSpec}
 import org.scalatest.junit.JUnitRunner
-import org.scalatest.matchers.{ShouldMatchers}
 
 
 @RunWith(classOf[JUnitRunner])
-class SequentialNodeNumbererSpec extends WordSpec with ShouldMatchers {
+class SequentialNodeNumbererSpec extends WordSpec with Matchers {
   "SequentialNodeNumberer" when {
     "numbering Longs" should {
       "use consecutive numbers" in {
@@ -39,7 +38,7 @@ class SequentialNodeNumbererSpec extends WordSpec with ShouldMatchers {
       }
       "raise exception when using internal id not defined so far" in {
         val numberer = new SequentialNodeNumberer[Long]
-        evaluating (numberer.internalToExternal(4)) should produce [IndexOutOfBoundsException]
+        an [IndexOutOfBoundsException] should be thrownBy numberer.internalToExternal(4)
       }
     }
     "numbering Strings" should {
@@ -59,7 +58,7 @@ class SequentialNodeNumbererSpec extends WordSpec with ShouldMatchers {
       }
       "raise exception when using internal id not defined so far" in {
         val numberer = new SequentialNodeNumberer[String]
-        evaluating (numberer.internalToExternal(4)) should produce [IndexOutOfBoundsException]
+        an [IndexOutOfBoundsException] should be thrownBy numberer.internalToExternal(4)
       }
     }
   }
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/util/SharedArraySeqSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/util/SharedArraySeqSpec.scala
index 93df5e04..8dff6023 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/util/SharedArraySeqSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/util/SharedArraySeqSpec.scala
@@ -13,10 +13,9 @@
  */
 package com.twitter.cassovary.util
 
-import org.scalatest.matchers.ShouldMatchers
-import org.scalatest.WordSpec
+import org.scalatest.{Matchers, WordSpec}
 
-class SharedArraySeqSpec extends WordSpec with ShouldMatchers {
+class SharedArraySeqSpec extends WordSpec with Matchers {
   val arr1 = Array(1,2,3)
   val arr2 = Array(4,5)
 
@@ -27,15 +26,15 @@ class SharedArraySeqSpec extends WordSpec with ShouldMatchers {
       "construct seqs correctly" in {
         val seq1 = new SharedArraySeq(0, sharedArray, 0, 3)
         seq1.toList shouldEqual arr1.toList
-        (new SharedArraySeq(0, sharedArray, 1, 2)).toList shouldEqual List(2, 3)
+        new SharedArraySeq(0, sharedArray, 1, 2).toList shouldEqual List(2, 3)
         seq1(0) shouldEqual 1
         seq1(1) shouldEqual 2
         seq1(2) shouldEqual 3
-        evaluating { seq1(3) } should produce [IndexOutOfBoundsException]
+        an [IndexOutOfBoundsException] should be thrownBy { seq1(3) }
       }
 
       "implement foreach correctly" in {
-        ((new SharedArraySeq(0, sharedArray, 0, 3)) map { _ + 1 }) shouldEqual List(2, 3, 4)
+        (new SharedArraySeq(0, sharedArray, 0, 3) map { _ + 1 }) shouldEqual List(2, 3, 4)
       }
     }
 
@@ -55,15 +54,15 @@ class SharedArraySeqSpec extends WordSpec with ShouldMatchers {
         seq1(0) shouldEqual 1
         seq1(1) shouldEqual 2
         seq1(2) shouldEqual 3
-        evaluating { seq1(3) } should produce [IndexOutOfBoundsException]
+        an [IndexOutOfBoundsException] should be thrownBy { seq1(3) }
 
         seq2(0) shouldEqual 4
         seq2(1) shouldEqual 5
-        evaluating { seq2(2) } should produce [IndexOutOfBoundsException]
+        an [IndexOutOfBoundsException] should be thrownBy { seq2(2) }
       }
 
       "implement foreach correctly" in {
-        ((new SharedArraySeq(111, sharedArray, 0, 2)) map { _ + 1 }) shouldEqual List(5, 6)
+        (new SharedArraySeq(111, sharedArray, 0, 2) map { _ + 1 }) shouldEqual List(5, 6)
       }
     }
   }
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/util/SmallBoundedPriorityQueueSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/util/SmallBoundedPriorityQueueSpec.scala
index c83f1b71..c56e77bc 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/util/SmallBoundedPriorityQueueSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/util/SmallBoundedPriorityQueueSpec.scala
@@ -13,12 +13,10 @@
  */
 package com.twitter.cassovary.util
 
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
-
+import org.scalatest.{Matchers, WordSpec}
 import scala.reflect.ClassTag
 
-class SmallBoundedPriorityQueueSpec extends WordSpec with ShouldMatchers {
+class SmallBoundedPriorityQueueSpec extends WordSpec with Matchers {
   def emptyQueue[A](maxSize: Int)(implicit m: ClassTag[A], ord: Ordering[A]) = {
     new SmallBoundedPriorityQueue[A](maxSize)
   }
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/util/io/AdjacencyListGraphReaderSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/util/io/AdjacencyListGraphReaderSpec.scala
index 4651c5ef..afc128eb 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/util/io/AdjacencyListGraphReaderSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/util/io/AdjacencyListGraphReaderSpec.scala
@@ -16,10 +16,9 @@ package com.twitter.cassovary.util.io
 import com.twitter.cassovary.graph.GraphBehaviours
 import com.twitter.cassovary.util.SequentialNodeNumberer
 import java.util.concurrent.Executors
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 
-class AdjacencyListGraphReaderSpec extends WordSpec with ShouldMatchers with GraphBehaviours {
+class AdjacencyListGraphReaderSpec extends WordSpec with Matchers with GraphBehaviours {
   val directory = "cassovary-core/src/test/resources/graphs/"
 
   val toy6nodeMap = Map( 10 -> List(11, 12, 13), 11 -> List(12, 14), 12 -> List(14),
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/util/io/GraphWriterSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/util/io/GraphWriterSpec.scala
index 229d2650..fb70b823 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/util/io/GraphWriterSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/util/io/GraphWriterSpec.scala
@@ -15,10 +15,9 @@ package com.twitter.cassovary.util.io
 
 import com.twitter.cassovary.graph.TestGraphs
 import java.io.StringWriter
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 
-class GraphWriterSpec extends WordSpec with ShouldMatchers {
+class GraphWriterSpec extends WordSpec with Matchers {
   "Graph writer" should {
     "write graph to single file" in {
       val graph = TestGraphs.g6
diff --git a/cassovary-core/src/test/scala/com/twitter/cassovary/util/io/ListOfEdgesGraphReaderSpec.scala b/cassovary-core/src/test/scala/com/twitter/cassovary/util/io/ListOfEdgesGraphReaderSpec.scala
index 32e7ba4b..209bcb2b 100644
--- a/cassovary-core/src/test/scala/com/twitter/cassovary/util/io/ListOfEdgesGraphReaderSpec.scala
+++ b/cassovary-core/src/test/scala/com/twitter/cassovary/util/io/ListOfEdgesGraphReaderSpec.scala
@@ -16,10 +16,9 @@ package com.twitter.cassovary.util.io
 import com.twitter.cassovary.graph.GraphBehaviours
 import com.twitter.cassovary.util.SequentialNodeNumberer
 import java.util.concurrent.Executors
-import org.scalatest.WordSpec
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.{Matchers, WordSpec}
 
-class ListOfEdgesGraphReaderSpec extends WordSpec with GraphBehaviours with ShouldMatchers {
+class ListOfEdgesGraphReaderSpec extends WordSpec with GraphBehaviours with Matchers {
 
   val intGraphMap = Map(1 -> List(2, 3), 2 -> List(3), 3 -> List(4), 4 -> List(1))