feat: Implement a BTBV TrustManager

test/trust_test.dart

@@ -0,0 +1,36 @@
+import 'package:omemo_dart/omemo_dart.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('Test the Blind Trust Before Verification TrustManager', () async {
+    // Caroline's BTBV manager
+    final btbv = BlindTrustBeforeVerificationTrustManager();
+    // 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);
+
+    // 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);
+
+    // 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);
+  });
+}