base64urlblob.go

package main

import "encoding/base64"

type Base64URLBlob []byte

var b64 = base64.URLEncoding

func (b Base64URLBlob) MarshalJSON() ([]byte, error) {
	dst := make([]byte, b64.EncodedLen(len(b))+2)
	dst[0], dst[len(dst)-1] = '"', '"'
	b64.Encode(dst[1:], []byte(b))
	return dst, nil
}

func (b *Base64URLBlob) UnmarshalJSON(p []byte) error {
	if len(p) < 2 {
		return nil
	}

	// Handle double quotes
	if p[0] == '"' && p[len(p)-1] == '"' {
		p = p[1 : len(p)-1]
	}

	dst := make([]byte, b64.DecodedLen(len(p)))
	n, err := b64.Decode(dst, p)
	if err != nil {
		return err
	}

	*b = Base64URLBlob(dst[:n])
	return nil
}

base64urlblob_test.go

package main

import (
	"encoding/json"
	"testing"
	"testing/quick"
)

// Base64URLBlob and its methods (MarshalJSON and UnmarshalJSON) are assumed to be defined here.

// checkConsistency ensures that marshaling and then unmarshaling a Base64URLBlob results in the original blob.
func checkConsistency(b Base64URLBlob) bool {
	marshaled, err := json.Marshal(b)
	if err != nil {
		return false
	}

	var unmarshaled Base64URLBlob
	err = json.Unmarshal(marshaled, &unmarshaled)
	if err != nil {
		return false
	}

	// Check if original and unmarshaled are the same
	return string(b) == string(unmarshaled)
}

// TestBase64URLBlobConsistency uses quickcheck to test the consistency of Base64URLBlob's marshal and unmarshal methods.
func TestBase64URLBlobConsistency(t *testing.T) {
	if err := quick.Check(checkConsistency, nil); err != nil {
		t.Error(err)
	}
}