initial import

core/mathx/unstable_test.go

@@ -0,0 +1,71 @@
+package mathx
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestUnstable_AroundDuration(t *testing.T) {
+	unstable := NewUnstable(0.05)
+	for i := 0; i < 1000; i++ {
+		val := unstable.AroundDuration(time.Second)
+		assert.True(t, float64(time.Second)*0.95 <= float64(val))
+		assert.True(t, float64(val) <= float64(time.Second)*1.05)
+	}
+}
+
+func TestUnstable_AroundInt(t *testing.T) {
+	const target = 10000
+	unstable := NewUnstable(0.05)
+	for i := 0; i < 1000; i++ {
+		val := unstable.AroundInt(target)
+		assert.True(t, float64(target)*0.95 <= float64(val))
+		assert.True(t, float64(val) <= float64(target)*1.05)
+	}
+}
+
+func TestUnstable_AroundIntLarge(t *testing.T) {
+	const target int64 = 10000
+	unstable := NewUnstable(5)
+	for i := 0; i < 1000; i++ {
+		val := unstable.AroundInt(target)
+		assert.True(t, 0 <= val)
+		assert.True(t, val <= 2*target)
+	}
+}
+
+func TestUnstable_AroundIntNegative(t *testing.T) {
+	const target int64 = 10000
+	unstable := NewUnstable(-0.05)
+	for i := 0; i < 1000; i++ {
+		val := unstable.AroundInt(target)
+		assert.Equal(t, target, val)
+	}
+}
+
+func TestUnstable_Distribution(t *testing.T) {
+	const (
+		seconds = 10000
+		total   = 10000
+	)
+
+	m := make(map[int]int)
+	expiry := NewUnstable(0.05)
+	for i := 0; i < total; i++ {
+		val := int(expiry.AroundInt(seconds))
+		m[val]++
+	}
+
+	_, ok := m[0]
+	assert.False(t, ok)
+
+	mi := make(map[interface{}]int, len(m))
+	for k, v := range m {
+		mi[k] = v
+	}
+	entropy := CalcEntropy(mi, total)
+	assert.True(t, len(m) > 1)
+	assert.True(t, entropy > 0.95)
+}