feat(tsdb): add interval calculator

pkg/tsdb/interval_test.go

@@ -0,0 +1,57 @@
+package tsdb
+
+import (
+	"testing"
+	"time"
+
+	"github.com/grafana/grafana/pkg/setting"
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestInterval(t *testing.T) {
+	Convey("Default interval ", t, func() {
+		setting.NewConfigContext(&setting.CommandLineArgs{
+			HomePath: "../../",
+		})
+
+		Convey("for 5min", func() {
+			tr := NewTimeRange("5m", "now")
+
+			interval := CalculateInterval(tr)
+			So(interval, ShouldEqual, "200ms")
+		})
+
+		Convey("for 15min", func() {
+			tr := NewTimeRange("15m", "now")
+
+			interval := CalculateInterval(tr)
+			So(interval, ShouldEqual, "500ms")
+		})
+
+		Convey("for 30min", func() {
+			tr := NewTimeRange("30m", "now")
+
+			interval := CalculateInterval(tr)
+			So(interval, ShouldEqual, "1s")
+		})
+
+		Convey("for 1h", func() {
+			tr := NewTimeRange("1h", "now")
+
+			interval := CalculateInterval(tr)
+			So(interval, ShouldEqual, "2s")
+		})
+
+		Convey("Round interval", func() {
+			So(roundInterval(time.Millisecond*30), ShouldEqual, time.Millisecond*20)
+			So(roundInterval(time.Millisecond*45), ShouldEqual, time.Millisecond*50)
+		})
+
+		Convey("Format value", func() {
+			So(formatDuration(time.Second*61), ShouldEqual, "1m")
+			So(formatDuration(time.Millisecond*30), ShouldEqual, "30ms")
+			So(formatDuration(time.Hour*23), ShouldEqual, "23h")
+			So(formatDuration(time.Hour*24*367), ShouldEqual, "1y")
+		})
+	})
+}