add test file

pkg/tsdb/testdata/scenarios_test.go

+package testdata
+
+import (
+	"testing"
+	"time"
+
+	"github.com/grafana/grafana/pkg/components/simplejson"
+	"github.com/grafana/grafana/pkg/tsdb"
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestTestdataScenarios(t *testing.T) {
+	Convey("random walk ", t, func() {
+		if scenario, exist := ScenarioRegistry["random_walk"]; exist {
+
+			Convey("Should start at the requested value", func() {
+				req := &tsdb.TsdbQuery{
+					TimeRange: tsdb.NewFakeTimeRange("5m", "now", time.Now()),
+					Queries: []*tsdb.Query{
+						{RefId: "A", IntervalMs: 100, MaxDataPoints: 10, Model: simplejson.New()},
+					},
+				}
+				query := req.Queries[0]
+				query.Model.Set("startValue", 1.234)
+
+				result := scenario.Handler(req.Queries[0], req)
+				points := result.Series[0].Points
+
+				So(result.Series, ShouldNotBeNil)
+				So(points[0][0].Float64, ShouldEqual, 1.234)
+			})
+
+		} else {
+			t.Fail()
+		}
+	})
+}