Added time.Time isEmpty check (go-ozzo#48)

* Added time.Time isEmpty check

* improved Required test

* improved Required test

Author: kfreiman

minmax_test.go

@@ -54,6 +54,7 @@ func TestMin(t *testing.T) {
 		{"t4.5", date20000601, true, date20000601, "must be greater than 2000-06-01 00:00:00 +0000 UTC"},
 		{"t4.6", date20000601, true, 1, "cannot convert int to time.Time"},
 		{"t4.7", struct{}{}, false, 1, "type not supported: struct {}"},
+		{"t4.8", date0, false, date20000601, ""},
 	}
 
 	for _, test := range tests {

required_test.go

@@ -6,13 +6,15 @@ package validation
 
 import (
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 )
 
 func TestRequired(t *testing.T) {
 	s1 := "123"
 	s2 := ""
+	var time1 time.Time
 	tests := []struct {
 		tag   string
 		value interface{}
@@ -23,6 +25,7 @@ func TestRequired(t *testing.T) {
 		{"t3", &s1, ""},
 		{"t4", &s2, "cannot be blank"},
 		{"t5", nil, "cannot be blank"},
+		{"t6", time1, "cannot be blank"},
 	}
 
 	for _, test := range tests {

util.go

@@ -9,6 +9,7 @@ import (
 	"errors"
 	"fmt"
 	"reflect"
+	"time"
 )
 
 var (
@@ -115,6 +116,11 @@ func IsEmpty(value interface{}) bool {
 			return true
 		}
 		return IsEmpty(v.Elem().Interface())
+	case reflect.Struct:
+		v, ok := value.(time.Time)
+		if ok && v.IsZero() {
+			return true
+		}
 	}
 
 	return false

util_test.go

@@ -6,6 +6,7 @@ package validation
 
 import (
 	"testing"
+	"time"
 
 	"database/sql"
 
@@ -196,6 +197,8 @@ func TestIsEmpty(t *testing.T) {
 	var s2 = "a"
 	var s3 *string
 	s4 := struct{}{}
+	time1 := time.Now()
+	var time2 time.Time
 	tests := []struct {
 		tag   string
 		value interface{}
@@ -251,6 +254,11 @@ func TestIsEmpty(t *testing.T) {
 		// struct
 		{"t9.1", s4, false},
 		{"t9.2", &s4, false},
+		// time.Time
+		{"t10.1", time1, false},
+		{"t10.2", &time1, false},
+		{"t10.3", time2, true},
+		{"t10.4", &time2, true},
 	}
 
 	for _, test := range tests {