b := NewReaderSize(strings.NewReader("hello world"), BufSize)
	// Does it recognize itself?
	b1 := NewReaderSize(b, BufSize)
	if b1 != b {
		t.Error("NewReaderSize did not detect underlying Reader")
	}
	// Does it wrap if existing buffer is too small?
	b2 := NewReaderSize(b, 2*BufSize)
	if b2 == b {
		t.Error("NewReaderSize did not enlarge buffer")
	}
}

func TestNewWriterSizeIdempotent(t *testing.T) {

	// to _cgoCheckPointer, as done in checkIndex and checkAddr.
	//
	// When the function argument is a conversion to unsafe.Pointer,
	// we unwrap the conversion before checking the pointer,
	// and then wrap again when calling C.f. This lets us check
	// the real type of the pointer in some cases. See issue #25941.
	//
	// When the call to C.f is deferred, we use an additional function

*/
package gmp

/*
#cgo LDFLAGS: -lgmp
#include <gmp.h>
#include <stdlib.h>

// gmp 5.0.0+ changed the type of the 3rd argument to mp_bitcnt_t,
// so, to support older versions, we wrap these two functions.
void _mpz_mul_2exp(mpz_ptr a, mpz_ptr b, unsigned long n) {
	mpz_mul_2exp(a, b, n);
}
void _mpz_div_2exp(mpz_ptr a, mpz_ptr b, unsigned long n) {
	mpz_div_2exp(a, b, n);
}
*/
import "C"