feat: add Date type

timex/date.go

@@ -0,0 +1,44 @@
+package timex
+
+import (
+	"encoding"
+	"fmt"
+	"time"
+)
+
+type Date struct {
+	Year  int
+	Month time.Month
+	Day   int
+}
+
+func NewDateFromTime(t time.Time) Date {
+	var d Date
+	d.Year, d.Month, d.Day = t.Date()
+	return d
+}
+
+func ParseDate(s string) (Date, error) {
+	t, err := time.Parse(time.DateOnly, s)
+	if err != nil {
+		return Date{}, err
+	}
+	return NewDateFromTime(t), nil
+}
+
+func (d Date) String() string {
+	return fmt.Sprintf("%04d-%02d-%02d", d.Year, d.Month, d.Day)
+}
+
+func (d Date) MarshalText() ([]byte, error) {
+	return []byte(d.String()), nil
+}
+
+func (d *Date) UnmarshalText(data []byte) error {
+	var err error
+	*d, err = ParseDate(string(data))
+	return err
+}
+
+var _ encoding.TextMarshaler = Date{}
+var _ encoding.TextUnmarshaler = &Date{}

timex/date_test.go

@@ -0,0 +1,42 @@
+package timex
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestParseDate(t *testing.T) {
+	tests := []struct {
+		str  string
+		want Date // if zero, expect an error
+	}{
+		{"1962-11-02", Date{1962, 11, 2}},
+		{"1962-12-31", Date{1962, 12, 31}},
+		{"0003-02-04", Date{3, 2, 4}},
+		{"999-01-26", Date{}},
+		{"", Date{}},
+		{"1962-01-02x", Date{}},
+	}
+
+	for _, tt := range tests {
+		got, err := ParseDate(tt.str)
+		assert.Equal(t, tt.want, got)
+		if got == (Date{}) {
+			assert.NotNil(t, err)
+		}
+	}
+}
+func TestMarshalJSON(t *testing.T) {
+	got, err := json.Marshal(Date{2023, 5, 4})
+	assert.Nil(t, err)
+	assert.Equal(t, `"2023-05-04"`, string(got))
+}
+
+func TestUnmarshalJSON(t *testing.T) {
+	var r Date
+	err := json.Unmarshal([]byte(`"2023-05-04"`), &r)
+	assert.Nil(t, err)
+	assert.Equal(t, Date{2023, 5, 4}, r)
+}