Represent serial numbers using SerialNumber struct

In a previous commit, we changed the serial number representation from a
string to an integer.  This made it easier to compare serial numbers,
but also introduced new problems:
- Serial numbers should be formatted consistently, for example as
  "{:#010x}".  It is hard to ensure this for an integer value.
- The format of the serial number may be subject to change.  Users
  should not rely too much on the u32 representation.

Therefore we introduce a new SerialNumber struct that represents a
serial number.  Currently it only stores a u32 value.  The following
traits and functions can be used to access its value:
- FromStr for string parsing
- ToString/Display for string formatting
- as_u32 to access the underlying integer value

1 files changed, 3 insertions, 3 deletions

diff --git a/tests/device.rs b/tests/device.rs
index 2989941..1669d9d 100644
--- a/tests/device.rs
+++ b/tests/device.rs
@@ -10,7 +10,7 @@ use std::{thread, time};
 use nitrokey::{
     Authenticate, CommandError, CommunicationError, Config, ConfigureOtp, Device, DeviceInfo,
     Error, GenerateOtp, GetPasswordSafe, LibraryError, OperationStatus, OtpMode, OtpSlotData,
-    Storage, VolumeMode, DEFAULT_ADMIN_PIN, DEFAULT_USER_PIN,
+    SerialNumber, Storage, VolumeMode, DEFAULT_ADMIN_PIN, DEFAULT_USER_PIN,
 };
 use nitrokey_test::test as test_device;
 
@@ -47,7 +47,7 @@ fn list_devices(_device: DeviceWrapper) {
                 nitrokey::Model::Pro => {
                     assert!(device.serial_number.is_some());
                     let serial_number = device.serial_number.unwrap();
-                    assert!(serial_number != 0);
+                    assert!(serial_number != SerialNumber::empty());
                 }
                 nitrokey::Model::Storage => {
                     assert_eq!(None, device.serial_number);
@@ -163,7 +163,7 @@ fn get_status(device: DeviceWrapper) {
 #[test_device]
 fn get_serial_number(device: DeviceWrapper) {
     let serial_number = unwrap_ok!(device.get_serial_number());
-    assert!(serial_number != 0);
+    assert!(serial_number != SerialNumber::empty());
 }
 
 #[test_device]