From 199f791885764c1736178a1132f08706efef8410 Mon Sep 17 00:00:00 2001
From: Tristan Swadell <tswadell@google.com>
Date: Thu, 21 May 2020 17:04:56 -0700
Subject: [PATCH] Add runtime support for timestamp from Unix epoch (#358)

---
 common/types/int.go             |  8 ++++++++
 common/types/int_test.go        |  7 +++++++
 interpreter/interpreter_test.go | 24 ++++++++++++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/common/types/int.go b/common/types/int.go
index c36accc1..8c586f59 100644
--- a/common/types/int.go
+++ b/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
 	}
diff --git a/common/types/int_test.go b/common/types/int_test.go
index 8c569163..95ccc347 100644
--- a/common/types/int_test.go
+++ b/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) {
diff --git a/interpreter/interpreter_test.go b/interpreter/interpreter_test.go
index 756b113a..8438ec0f 100644
--- a/interpreter/interpreter_test.go
+++ b/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')`,