func (ident DockerConfigEntry) MarshalJSON() ([]byte, error) {
	toEncode := dockerConfigEntryWithAuth{ident.Username, ident.Password, ident.Email, ""}
	toEncode.Auth = encodeDockerConfigFieldAuth(ident.Username, ident.Password)

	return json.Marshal(toEncode)
}

// decodeDockerConfigFieldAuth deserializes the "auth" field from dockercfg into a

		{
			input:    base64.RawStdEncoding.EncodeToString([]byte("foo:bar")),
			username: "foo",
			password: "bar",
		},

		// the input is encoded with encodeDockerConfigFieldAuth (standard encoding)
		{
			input:    encodeDockerConfigFieldAuth("foo", "bar"),
			username: "foo",
			password: "bar",
		},

		// good base64 data, but no colon separating username & password
		{
			input: "cGFudHM=",