Add Optional Timezone to now()

Add support for an optional timezone argument to now().  Formatting the
returned time will use the specified timezone.

Author: cwarden

builtin/builtin.go

@@ -472,9 +472,20 @@ var Builtins = []*Function{
 	{
 		Name: "now",
 		Func: func(args ...any) (any, error) {
+			if len(args) == 1 {
+				timeZone := args[0].(string)
+				tz, err := time.LoadLocation(timeZone)
+				if err != nil {
+					return nil, err
+				}
+				return time.Now().In(tz), nil
+			}
 			return time.Now(), nil
 		},
-		Types: types(new(func() time.Time)),
+		Types: types(
+			new(func() time.Time),
+			new(func(string) time.Time),
+		),
 	},
 	{
 		Name: "duration",

builtin/builtin_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/agiledragon/gomonkey/v2"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
@@ -28,6 +29,12 @@ func TestBuiltin(t *testing.T) {
 		"PtrArrayWithNil": &ArrayWithNil,
 	}
 
+	// Monkey patch time.Now so we get a consistent timestamp
+	patches := gomonkey.ApplyFunc(time.Now, func() time.Time {
+		return time.Unix(946706400, 0)
+	})
+	defer patches.Reset()
+
 	var tests = []struct {
 		input string
 		want  any
@@ -110,6 +117,8 @@ func TestBuiltin(t *testing.T) {
 		{`toBase64("hello")`, "aGVsbG8="},
 		{`fromBase64("aGVsbG8=")`, "hello"},
 		{`now().Format("2006-01-02T15:04Z")`, time.Now().Format("2006-01-02T15:04Z")},
+		{`now("America/Chicago").Format("2006-01-02T15:04Z")`, "2000-01-01T00:00Z"},
+		{`now("Europe/Bratislava").Format("2006-01-02T15:04Z")`, "2000-01-01T07:00Z"},
 		{`duration("1h")`, time.Hour},
 		{`date("2006-01-02T15:04:05Z")`, time.Date(2006, 1, 2, 15, 4, 5, 0, time.UTC)},
 		{`date("2006.01.02", "2006.01.02")`, time.Date(2006, 1, 2, 0, 0, 0, 0, time.UTC)},

go.mod

@@ -2,7 +2,10 @@ module github.com/expr-lang/expr
 
 go 1.18
 
-require github.com/stretchr/testify v1.8.4
+require (
+	github.com/agiledragon/gomonkey/v2 v2.11.0
+	github.com/stretchr/testify v1.8.4
+)
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect

go.sum

@@ -1,9 +1,20 @@
+github.com/agiledragon/gomonkey/v2 v2.11.0 h1:5oxSgA+tC1xuGsrIorR+sYiziYltmJyEZ9qA25b6l5U=
+github.com/agiledragon/gomonkey/v2 v2.11.0/go.mod h1:ap1AmDzcVOAz1YpeJ3TCzIgstoaWLA6jbbgxfB4w2iY=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
+github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d/go.mod h1:OnSkiWE9lh6wB0YB77sQom3nweQdgAjqCqsofrRNTgc=
+github.com/smartystreets/goconvey v1.6.4/go.mod h1:syvi0/a8iFYH4r/RixwvyeAJjdLS9QV7WQ/tjFTllLA=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20190328211700-ab21143f2384/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=