Add runtime support for timestamp from Unix epoch (#358)

common/types/int.go

@@ -18,6 +18,7 @@ import (
 	"fmt"
 	"reflect"
 	"strconv"
+	"time"
 
 	"github.com/golang/protobuf/ptypes"
 
@@ -163,6 +164,13 @@ func (i Int) ConvertToType(typeVal ref.Type) ref.Val {
 		return Double(i)
 	case StringType:
 		return String(fmt.Sprintf("%d", int64(i)))
+	case TimestampType:
+		t := time.Unix(int64(i), 0)
+		ts, err := ptypes.TimestampProto(t)
+		if err != nil {
+			return NewErr(err.Error())
+		}
+		return Timestamp{Timestamp: ts}
 	case TypeType:
 		return IntType
 	}

common/types/int_test.go

@@ -18,6 +18,7 @@ import (
 	"math"
 	"reflect"
 	"testing"
+	"time"
 
 	"github.com/golang/protobuf/proto"
 	"github.com/golang/protobuf/ptypes"
@@ -178,6 +179,12 @@ func TestInt_ConvertToType(t *testing.T) {
 	if !IsError(Int(-4).ConvertToType(DurationType)) {
 		t.Error("Got duration, expected error.")
 	}
+	tm := time.Unix(946684800, 0)
+	ts, _ := ptypes.TimestampProto(tm)
+	celts := Timestamp{Timestamp: ts}
+	if !Int(946684800).ConvertToType(TimestampType).Equal(celts).(Bool) {
+		t.Error("unsuccessful type conversion to timestamp")
+	}
 }
 
 func TestInt_Divide(t *testing.T) {

interpreter/interpreter_test.go

@@ -390,6 +390,30 @@ var (
 				RepeatedInt32: []int32{0, 2},
 			},
 		},
+		{
+			name: "timestamp_eq_timestamp",
+			expr: `timestamp(0) == timestamp(0)`,
+		},
+		{
+			name: "timestamp_eq_timestamp",
+			expr: `timestamp(1) != timestamp(2)`,
+		},
+		{
+			name: "timestamp_lt_timestamp",
+			expr: `timestamp(0) < timestamp(1)`,
+		},
+		{
+			name: "timestamp_le_timestamp",
+			expr: `timestamp(2) <= timestamp(2)`,
+		},
+		{
+			name: "timestamp_gt_timestamp",
+			expr: `timestamp(1) > timestamp(0)`,
+		},
+		{
+			name: "timestamp_ge_timestamp",
+			expr: `timestamp(2) >= timestamp(2)`,
+		},
 		{
 			name: "string_to_timestamp",
 			expr: `timestamp('1986-04-26T01:23:40Z')`,