t.Run("uint16max-1_NoZip64", func(t *testing.T) {
		t.Parallel()
		if generatesZip64(t, gen(0xfffe)) {
			t.Error("unexpected zip64")
		}
	})
	// 16k records should make a zip64:
	t.Run("uint16max_Zip64", func(t *testing.T) {
		t.Parallel()
		if !generatesZip64(t, gen(0xffff)) {
			t.Error("expected zip64")
		}
	})
}

// suffixSaver is an io.Writer & io.ReaderAt that remembers the last 0