sql datasource: extract common logic for converting time column to epoch time in ms

pkg/tsdb/sql_engine_test.go

@@ -0,0 +1,46 @@
+package tsdb
+
+import (
+	"testing"
+	"time"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestSqlEngine(t *testing.T) {
+	Convey("SqlEngine", t, func() {
+		Convey("Given row values with time columns when converting them", func() {
+			dt := time.Date(2018, 3, 14, 21, 20, 6, 527e6, time.UTC)
+			fixtures := make([]interface{}, 8)
+			fixtures[0] = dt
+			fixtures[1] = dt.Unix() * 1000
+			fixtures[2] = dt.Unix()
+			fixtures[3] = float64(dt.Unix() * 1000)
+			fixtures[4] = float64(dt.Unix())
+
+			var nilDt *time.Time
+			var nilInt64 *int64
+			var nilFloat64 *float64
+			fixtures[5] = nilDt
+			fixtures[6] = nilInt64
+			fixtures[7] = nilFloat64
+
+			for i := range fixtures {
+				ConvertSqlTimeColumnToEpochMs(fixtures, i)
+			}
+
+			Convey("Should convert sql time columns to epoch time in ms ", func() {
+				expected := float64(dt.Unix() * 1000)
+				So(fixtures[0].(float64), ShouldEqual, expected)
+				So(fixtures[1].(int64), ShouldEqual, expected)
+				So(fixtures[2].(int64), ShouldEqual, expected)
+				So(fixtures[3].(float64), ShouldEqual, expected)
+				So(fixtures[4].(float64), ShouldEqual, expected)
+
+				So(fixtures[5], ShouldBeNil)
+				So(fixtures[6], ShouldBeNil)
+				So(fixtures[7], ShouldBeNil)
+			})
+		})
+	})
+}