feat: implement TextMarshaler and TextUnmarshaler for IntOrString

Implement text marshaling for IntOrString. This allows IntOrString to be
used as map keys when marshaling to/form JSON.

Signed-off-by: setrofim <setrofim@gmail.com>

Author: setrofim

int_or_string.go

@@ -171,3 +171,12 @@ func (o *IntOrString) UnmarshalJSON(data []byte) error {
 
 	return nil
 }
+
+func (o IntOrString) MarshalText() ([]byte, error) {
+	return []byte(o.String()), nil
+}
+
+func (o *IntOrString) UnmarshalText(data []byte) error {
+	*o = IntOrStringFromString(string(data))
+	return nil
+}

int_or_string_test.go

@@ -4,6 +4,7 @@
 package eat
 
 import (
+	"encoding/json"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -171,3 +172,19 @@ func TestIntOrString_misc(t *testing.T) {
 	ios = IntOrStringFromString("1")
 	assert.Equal(t, 1, ios.Int())
 }
+
+func TestIntOrString_JSON_key(t *testing.T) {
+	toEncode := map[IntOrString]any{
+		IntOrStringFromString("foo"): 1,
+	}
+
+	expectedJSON := `{"foo": 1}`
+	encoded, err := json.Marshal(toEncode)
+	assert.NoError(t, err)
+	assert.JSONEq(t, expectedJSON, string(encoded))
+
+	var decoded map[IntOrString]any
+	err = json.Unmarshal(encoded, &decoded)
+	assert.NoError(t, err)
+	assert.EqualValues(t, 1, int(decoded[IntOrStringFromString("foo")].(float64)))
+}