// 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) {
	const BufSize = 1000

	off := int64(0)

	// Rename struct fields that happen to be named Go keywords into
	// _{keyword}.  Create a map from C ident -> Go ident. The Go ident will
	// be mangled. Any existing identifier that already has the same name on
	// the C-side will cause the Go-mangled version to be prefixed with _.
	// (e.g. in a struct with fields '_type' and 'type', the latter would be
	// rendered as '__type' in Go).