mysql: began work on backend macro engine

pkg/tsdb/mysql/macros_test.go

@@ -0,0 +1,22 @@
+package mysql
+
+import (
+	"testing"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestMacroEngine(t *testing.T) {
+	Convey("MacroEngine", t, func() {
+
+		Convey("interpolate simple function", func() {
+			engine := &MySqlMacroEngine{}
+
+			sql, err := engine.Interpolate("select $__time(time_column)")
+			So(err, ShouldBeNil)
+
+			So(sql, ShouldEqual, "select UNIX_TIMESTAMP(time_column) as time_sec")
+		})
+
+	})
+}