diff --git a/Test/Tests/RealtimeClientChannelTests.swift b/Test/Tests/RealtimeClientChannelTests.swift
index 3db6ca63d..e4d7d0b30 100644
--- a/Test/Tests/RealtimeClientChannelTests.swift
+++ b/Test/Tests/RealtimeClientChannelTests.swift
@@ -4785,4 +4785,18 @@ class RealtimeClientChannelTests: XCTestCase {
             }
         }
     }
+    
+    // CP2
+    func test__140__attributes_of_ChannelProperties_consist_of_attachSerial_and_channelSerial() throws {
+        let test = Test()
+        let client = ARTRealtime(options: try AblyTests.commonAppSetup(for: test))
+        defer { client.dispose(); client.close() }
+        let channel = client.channels.get(test.uniqueChannelName())
+        XCTAssertNil(channel.properties.attachSerial)
+        XCTAssertNil(channel.properties.channelSerial)
+        channel.internal.attachSerial = "foo"
+        channel.internal.channelSerial = "bar"
+        XCTAssertEqual(channel.properties.attachSerial, "foo")
+        XCTAssertEqual(channel.properties.channelSerial, "bar")
+    }
 }