@Before
  public void initialize() {
    Properties props = new Properties();
    props.setProperty("router.hostname", "localhost");
    props.setProperty("router.datacenter.name", "DC1");
    props.setProperty("router.scaling.unit.max.connections.per.port.plain.text", "3");
    props.setProperty("router.scaling.unit.max.connections.per.port.ssl", "2");
    verifiableProperties = new VerifiableProperties((props));
    routerConfig = new RouterConfig(verifiableProperties);
    networkConfig = new NetworkConfig(verifiableProperties);
    time = new MockTime();
    plainTextPort = new Port(100, PortType.PLAINTEXT);
    sslPort = new Port(200, PortType.SSL);
  }
Tests the {@link ConnectionTracker}. Checks out and checks in connections and ensures that the pool
totalConnectionsCount is honored. Also tests removing connections and closing the connection manager.
ambry-network/src/test/java/com/github/ambry/network/ConnectionTrackerTest.java