// Checking the error cases first.
	p.collectMetricsData(cpuCounter, memWorkingSetCounter, memCommittedBytesCounter, networkAdapterCounter)
	metrics, _ := p.getNodeMetrics()
	expectedMetrics := nodeMetrics{}
	assert.Equal(t, expectedMetrics, metrics)

	cpuCounter.raiseError = false
	p.collectMetricsData(cpuCounter, memWorkingSetCounter, memCommittedBytesCounter, networkAdapterCounter)

	if err != nil {
		return err
	}

	networkAdapterCounter, err := newNetworkCounters()
	if err != nil {
		return err
	}

	go wait.Forever(func() {
		p.collectMetricsData(cpuCounter, memWorkingSetCounter, memCommittedBytesCounter, networkAdapterCounter)
	}, perfCounterUpdatePeriod)

	// Cache the CPU usage every defaultCachePeriod
	go wait.Forever(func() {