package ostat

import (
	"math"
	"testing"
)

func TestInsert(t *testing.T) {
	os := NewOnlineStat()
	v := []float64{4, 7, 13, 16}
	for _, i := range v {
		os.Push(i)
	}
	if os.Min != 4 {
		t.Errorf("incorrectly calculated min")
	}
	if os.Max != 16 {
		t.Errorf("incorrectly calculated max")
	}
	if m, _ := os.Mean(); m != 10.0 {
		t.Errorf("incorrect mean")
	}
	if variance, _ := os.Variance(); variance != 30.0 {
		t.Errorf("incorrect variance: %f", variance)
	}
	if stdev, _ := os.StdDev(); stdev != math.Sqrt(30.0) {
		t.Errorf("incorrect stdev: %f", stdev)
	}
}

func TestEmpty(t *testing.T) {
	os := NewOnlineStat()
	_, err := os.Mean()
	if err == nil {
		t.Errorf("failure to notify the running stat was empty")
	}
	_, err = os.Variance()
	if err == nil {
		t.Errorf("failure to notify the running stat was empty")
	}
	_, err = os.StdDev()
	if err == nil {
		t.Errorf("failure to notify the running stat was empty")
	}
}