func TestIntReading(t *testing.T) {
	intStrs := [...]string{"0", "1", "+100", "-982", "8223372036854775808", "-5N", "-0N"}
	ints := [...]int64{0, 1, 100, -982, 8223372036854775808, -5, 0}
	for i, istr := range intStrs {
		var n int64
		err := UnmarshalString(istr, &n)
		if err != nil {
			t.Errorf("int64 '%s' failed, but expected success", istr)
		} else if n != ints[i] {
			t.Errorf("int64 '%s' was decoded to %d, but expected %d", istr, n, ints[i])
		}
	}
}
your basic unit tests.. unfinished, probably.
package edn
import (
	"fmt"
	"math/big"
	"reflect"
	"strings"
	"testing"
)