Create trig plugin

closes #404

plugins/all/all.go

@@ -28,6 +28,7 @@ import (
 	_ "github.com/influxdb/telegraf/plugins/rethinkdb"
 	_ "github.com/influxdb/telegraf/plugins/statsd"
 	_ "github.com/influxdb/telegraf/plugins/system"
+	_ "github.com/influxdb/telegraf/plugins/trig"
 	_ "github.com/influxdb/telegraf/plugins/twemproxy"
 	_ "github.com/influxdb/telegraf/plugins/zfs"
 	_ "github.com/influxdb/telegraf/plugins/zookeeper"

plugins/trig/trig.go

@@ -0,0 +1,46 @@
+package trig
+
+import (
+	"math"
+
+	"github.com/influxdb/telegraf/plugins"
+)
+
+type Trig struct {
+	x         float64
+	Amplitude float64
+}
+
+var TrigConfig = `
+  # Set the amplitude
+  amplitude = 10.0
+`
+
+func (s *Trig) SampleConfig() string {
+	return TrigConfig
+}
+
+func (s *Trig) Description() string {
+	return "Inserts sine and cosine waves for demonstration purposes"
+}
+
+func (s *Trig) Gather(acc plugins.Accumulator) error {
+	sinner := math.Sin((s.x*math.Pi)/5.0) * s.Amplitude
+	cosinner := math.Cos((s.x*math.Pi)/5.0) * s.Amplitude
+
+	fields := make(map[string]interface{})
+	fields["sine"] = sinner
+	fields["cosine"] = cosinner
+
+	tags := make(map[string]string)
+
+	s.x += 1.0
+	acc.AddFields("trig", fields, tags)
+
+	return nil
+}
+
+func init() {
+
+	plugins.Add("Trig", func() plugins.Plugin { return &Trig{x: 0.0} })
+}

plugins/trig/trig_test.go

@@ -0,0 +1,33 @@
+package trig
+
+import (
+	"math"
+	"testing"
+
+	"github.com/influxdb/telegraf/testutil"
+	"github.com/stretchr/testify/assert"
+	// "github.com/stretchr/testify/require"
+)
+
+func TestTrig(t *testing.T) {
+	s := &Trig{
+		Amplitude: 10.0,
+	}
+
+	for i := 0.0; i < 10.0; i++ {
+
+		var acc testutil.Accumulator
+
+		sine := math.Sin((i*math.Pi)/5.0) * s.Amplitude
+		cosine := math.Cos((i*math.Pi)/5.0) * s.Amplitude
+
+		s.Gather(&acc)
+
+		fields := make(map[string]interface{})
+		fields["sine"] = sine
+		fields["cosine"] = cosine
+
+		assert.True(t, acc.CheckFieldsValue("trig", fields))
+
+	}
+}