add test for unpairing request message

ts/session/messages/outgoing/content/data/DeviceUnlinkMessage.ts

@@ -8,6 +8,10 @@ export class DeviceUnlinkMessage extends DataMessage {
   }
 
   protected dataProto(): SignalService.DataMessage {
-    throw new Error('Not implemented');
+    const flags = SignalService.DataMessage.Flags.UNPAIRING_REQUEST;
+
+    return new SignalService.DataMessage({
+      flags,
+    });
   }
 }

ts/test/session/messages/DeviceUnlinkMessage_test.ts

@@ -0,0 +1,30 @@
+// tslint:disable: no-implicit-dependencies
+import { assert} from 'chai';
+import { beforeEach} from 'mocha';
+
+import { DeviceUnlinkMessage } from '../../../session/messages/outgoing';
+import { SignalService } from '../../../protobuf';
+
+describe('DeviceUnlinkMessage', () => {
+    let message: DeviceUnlinkMessage;
+    beforeEach(() => {
+        message = new DeviceUnlinkMessage(Date.now(), '123456');
+    });
+
+    it('content of just the UNPAIRING_REQUEST flag set', () => {
+        const plainText = message.plainTextBuffer();
+        const decoded = SignalService.Content.decode(plainText).toJSON();
+
+        const expected = {
+            dataMessage: {
+                flags: SignalService.DataMessage.Flags.UNPAIRING_REQUEST,
+            },
+        };
+
+        assert.deepEqual(decoded, expected);
+    });
+
+    it('ttl of 4 days', () => {
+        assert.equal(message.ttl(), 4 * 24 * 60 * 60 * 1000);
+    });
+});