add a test and improve a test

src/olm/account/mod.rs

@@ -533,7 +533,7 @@ impl Account {
         pickle.try_into()
     }
 
-    #[cfg(fuzzing)]
+    #[cfg(any(fuzzing, test))]
     #[doc(hidden)]
     pub fn from_decrypted_dehydrated_device(
         pickle: &[u8],
@@ -1459,6 +1459,7 @@ mod test {
     fn decrypt_with_dehydrated_device() -> Result<()> {
         let mut alice = Account::new();
         let bob = Account::new();
+        let carol = Account::new();
 
         alice.generate_one_time_keys(alice.max_number_of_one_time_keys());
         alice.generate_fallback_key();
@@ -1477,8 +1478,20 @@ mod test {
                 .1,
         );
 
+        let mut carol_session = carol.create_outbound_session(
+            SessionConfig::version_1(),
+            alice.curve25519_key(),
+            *alice
+                .fallback_key()
+                .iter()
+                .next()
+                .context("Failed getting alice's fallback key, which should never happen here.")?
+                .1,
+        );
+
         let message = "It's a secret to everybody";
-        let olm_message = bob_session.encrypt(message);
+        let bob_olm_message = bob_session.encrypt(message);
+        let carol_olm_message = carol_session.encrypt(message);
 
         let mut alice_rehydrated = Account::from_dehydrated_device(
             &alice_dehydrated_result.ciphertext,
@@ -1487,7 +1500,7 @@ mod test {
         )
         .expect("Should be able to rehydrate device");
 
-        if let OlmMessage::PreKey(m) = olm_message {
+        if let OlmMessage::PreKey(m) = bob_olm_message {
             let InboundCreationResult { session: alice_session, plaintext } =
                 alice_rehydrated.create_inbound_session(bob.curve25519_key(), &m)?;
 
@@ -1497,6 +1510,16 @@ mod test {
             panic!("Expected a pre-key message");
         }
 
+        if let OlmMessage::PreKey(m) = carol_olm_message {
+            let InboundCreationResult { session: alice_session, plaintext } =
+                alice_rehydrated.create_inbound_session(carol.curve25519_key(), &m)?;
+
+            assert_eq!(alice_session.session_id(), carol_session.session_id());
+            assert_eq!(message.as_bytes(), plaintext);
+        } else {
+            panic!("Expected a pre-key message");
+        }
+
         Ok(())
     }
 
@@ -1559,4 +1582,21 @@ mod test {
 
         Ok(())
     }
+
+    #[test]
+    fn decrypted_dehydration_cycle() {
+        use dehydrated_device::Pickle;
+
+        let alice = Account::new();
+
+        let mut encoded = Vec::<u8>::new();
+        let pickle = Pickle::from(&alice);
+        let size = pickle.encode(&mut encoded).expect("Should dehydrate");
+        assert_eq!(size, encoded.len());
+
+        let account =
+            Account::from_decrypted_dehydrated_device(&encoded).expect("Should rehydrate account");
+
+        assert_eq!(alice.identity_keys(), account.identity_keys());
+    }
 }