fix: Make fromJson* functions work when reading JSON from a String

lib/src/double_ratchet/double_ratchet.dart

@@ -94,11 +94,20 @@ class OmemoDoubleRatchet {
       ]
     }
     */
-    final mkSkipped = <SkippedKey, List<int>>{};
+    // NOTE: Dart has some issues with just casting a List<dynamic> to List<Map<...>>, as
-    for (final entry in data['mkskipped']! as List<Map<String, dynamic>>) {
+    //       such we need to convert the items by hand.
-      final key = SkippedKey.fromJson(entry);
+    final mkSkipped = Map<SkippedKey, List<int>>.fromEntries(
-      mkSkipped[key] = base64.decode(entry['key']! as String);
+      (data['mkskipped']! as List<dynamic>).map<MapEntry<SkippedKey, List<int>>>(
-    }
+        (entry) {
+          final map = entry as Map<String, dynamic>;
+          final key = SkippedKey.fromJson(map);
+          return MapEntry(
+            key,
+            base64.decode(map['key']! as String),
+          );
+        },
+      ),
+    );
     
     return OmemoDoubleRatchet(
       OmemoKeyPair.fromBytes(

lib/src/omemo/device.dart

@@ -49,14 +49,23 @@ class Device {
       ]
     }
     */
-    final opks = <int, OmemoKeyPair>{};
+    // NOTE: Dart has some issues with just casting a List<dynamic> to List<Map<...>>, as
-    for (final opk in data['opks']! as List<Map<String, dynamic>>) {
+    //       such we need to convert the items by hand.
-      opks[opk['id']! as int] = OmemoKeyPair.fromBytes(
+    final opks = Map<int, OmemoKeyPair>.fromEntries(
-        base64.decode(opk['public']! as String),
+      (data['opks']! as List<dynamic>).map<MapEntry<int, OmemoKeyPair>>(
-        base64.decode(opk['private']! as String),
+        (opk) {
-        KeyPairType.x25519,
+          final map = opk as Map<String, dynamic>;
-      );
+          return MapEntry(
-    }
+            map['id']! as int,
+            OmemoKeyPair.fromBytes(
+              base64.decode(map['public']! as String),
+              base64.decode(map['private']! as String),
+              KeyPairType.x25519,
+            ),
+          );
+        },
+      ),
+    );
 
     return Device(
       data['jid']! as String,

lib/src/omemo/sessionmanager.dart

@@ -37,10 +37,23 @@ class OmemoSessionManager {
 
   /// Deserialise the OmemoSessionManager from JSON data [data] that does not contain
   /// the ratchet sessions.
-  factory OmemoSessionManager.fromJsonWithoutSessions(Map<String, dynamic> data, Map<RatchetMapKey, OmemoDoubleRatchet> ratchetMap, TrustManager trustManager) {
+  factory OmemoSessionManager.fromJsonWithoutSessions(
+    Map<String, dynamic> data,
+    Map<RatchetMapKey, OmemoDoubleRatchet> ratchetMap,
+    TrustManager trustManager,
+  ) {
+    // NOTE: Dart has some issues with just casting a List<dynamic> to List<Map<...>>, as
+    //       such we need to convert the items by hand.
     return OmemoSessionManager(
       Device.fromJson(data['device']! as Map<String, dynamic>),
-      data['devices']! as Map<String, List<int>>,
+      (data['devices']! as Map<String, dynamic>).map<String, List<int>>(
+        (key, value) {
+          return MapEntry(
+            key,
+            (value as List<dynamic>).map<int>((i) => i as int).toList(),
+          );
+        }
+      ),
       ratchetMap,
       trustManager,
     );

test/serialisation_test.dart

@@ -3,6 +3,10 @@ import 'package:omemo_dart/omemo_dart.dart';
 import 'package:omemo_dart/src/trust/always.dart';
 import 'package:test/test.dart';
 
+Map<String, dynamic> jsonify(Map<String, dynamic> map) {
+  return jsonDecode(jsonEncode(map)) as Map<String, dynamic>;
+}
+
 void main() {
   test('Test serialising and deserialising the Device', () async {
     // Generate a random session
@@ -12,7 +16,7 @@ void main() {
       opkAmount: 1,
     );
     final oldDevice = await oldSession.getDevice();
-    final serialised = await oldDevice.toJson();
+    final serialised = jsonify(await oldDevice.toJson());
 
     final newDevice = Device.fromJson(serialised);
     expect(await oldDevice.equals(newDevice), true);
@@ -26,7 +30,7 @@ void main() {
       opkAmount: 1,
     );
     final oldDevice = await (await oldSession.getDevice()).replaceSignedPrekey();
-    final serialised = await oldDevice.toJson();
+    final serialised = jsonify(await oldDevice.toJson());
 
     final newDevice = Device.fromJson(serialised);
     expect(await oldDevice.equals(newDevice), true);
@@ -60,7 +64,7 @@ void main() {
       aliceMessage.encryptedKeys,
     );
     final aliceOld = aliceSession.getRatchet(bobJid, await bobSession.getDeviceId());
-    final aliceSerialised = await aliceOld.toJson();
+    final aliceSerialised = jsonify(await aliceOld.toJson());
     final aliceNew = OmemoDoubleRatchet.fromJson(aliceSerialised);
 
     expect(await aliceOld.equals(aliceNew), true);
@@ -85,7 +89,7 @@ void main() {
     );
 
     // Serialise and deserialise
-    final serialised = await oldSession.toJsonWithoutSessions();
+    final serialised = jsonify(await oldSession.toJsonWithoutSessions());
     final newSession = OmemoSessionManager.fromJsonWithoutSessions(
       serialised,
       // NOTE: At this point, we don't care about this attribute
@@ -99,42 +103,6 @@ void main() {
     expect(await oldSession.getDeviceMap(), await newSession.getDeviceMap());
   });
 
-  test('Test serialising and deserialising the BlindTrustBeforeVerificationTrustManager', () async {
-    // Caroline's BTBV manager
-    final btbv = MemoryBTBVTrustManager();
-    // Example data
-    const aliceJid = 'alice@some.server';
-    const bobJid = 'bob@other.server';
-    
-    // Caroline starts a chat a device from Alice
-    await btbv.onNewSession(aliceJid, 1);
-    expect(await btbv.isTrusted(aliceJid, 1), true);
-    expect(await btbv.isEnabled(aliceJid, 1), true);
-
-    // Caroline meets with Alice and verifies her fingerprint
-    await btbv.setDeviceTrust(aliceJid, 1, BTBVTrustState.verified);
-    expect(await btbv.isTrusted(aliceJid, 1), true);
-
-    // Alice adds a new device
-    await btbv.onNewSession(aliceJid, 2);
-    expect(await btbv.isTrusted(aliceJid, 2), false);
-    expect(btbv.getDeviceTrust(aliceJid, 2), BTBVTrustState.notTrusted);
-    expect(await btbv.isEnabled(aliceJid, 2), false);
-
-    // Caronline starts a chat with Bob but since they live far apart, Caroline cannot
-    // verify his fingerprint.
-    await btbv.onNewSession(bobJid, 3);
-
-    // Bob adds a new device
-    await btbv.onNewSession(bobJid, 4);
-    expect(await btbv.isTrusted(bobJid, 3), true);
-    expect(await btbv.isTrusted(bobJid, 4), true);
-    expect(btbv.getDeviceTrust(bobJid, 3), BTBVTrustState.blindTrust);
-    expect(btbv.getDeviceTrust(bobJid, 4), BTBVTrustState.blindTrust);
-    expect(await btbv.isEnabled(bobJid, 3), true);
-    expect(await btbv.isEnabled(bobJid, 4), true);
-  });
-
   test('Test serializing and deserializing RatchetMapKey', () {
     const test1 = RatchetMapKey('user@example.org', 1234);
     final result1 = RatchetMapKey.fromJsonKey(test1.toJsonKey());
@@ -160,21 +128,19 @@ void main() {
     await btbv.onNewSession(bobJid, 3);
     await btbv.onNewSession(bobJid, 4);
 
-    final managerJson = await btbv.toJson();
+    final serialized = jsonify(await btbv.toJson());
-    final managerString = jsonEncode(managerJson);
-    final managerPostJson = jsonDecode(managerString) as Map<String, dynamic>;
     final deviceList = BlindTrustBeforeVerificationTrustManager.deviceListFromJson(
-      managerPostJson,
+      serialized,
     );
     expect(btbv.devices, deviceList);
 
     final trustCache = BlindTrustBeforeVerificationTrustManager.trustCacheFromJson(
-      managerPostJson,
+      serialized,
     );
     expect(btbv.trustCache, trustCache);
 
     final enableCache = BlindTrustBeforeVerificationTrustManager.enableCacheFromJson(
-      managerPostJson,
+      serialized,
     );
     expect(btbv.enablementCache, enableCache);
   });