Ensure atomicity when removing last registered session owner

1 files changed, 2 insertions, 1 deletions

diff --git a/messagebus/src/test/java/com/yahoo/messagebus/network/NetworkMultiplexerTest.java b/messagebus/src/test/java/com/yahoo/messagebus/network/NetworkMultiplexerTest.java
index 60da1b49d90..57ded9f750d 100644
--- a/messagebus/src/test/java/com/yahoo/messagebus/network/NetworkMultiplexerTest.java
+++ b/messagebus/src/test/java/com/yahoo/messagebus/network/NetworkMultiplexerTest.java
@@ -43,7 +43,8 @@ public class NetworkMultiplexerTest {
             fail("Illegal to register same session multiple times with the same owner");
         }
         catch (IllegalArgumentException expected) {
-            assertEquals("Session 's1' with owner 'mock owner' already registered with this", expected.getMessage());
+            assertEquals("Session 's1' with owner 'mock owner' already registered with network multiplexer with owners: [mock owner], sessions: {s1=[mock owner]} and destructible: false",
+                         expected.getMessage());
         }
         assertEquals(Set.of("s1"), net.registered);