void init() {
        updater = new ObservableUpdater();
        metricManager = MetricManager.constructWithCustomUpdater(new ManagerConfig(new ManagerConfig.Builder()), updater);
        receiver = metricManager.get();
    }
Common code for running unit tests of simplemetrics

@author ean
container-core/src/main/java/com/yahoo/metrics/simple/UnitTestSetup.java