From 08236466c5b2871d860b0bbfdfa6a0774bda2e6f Mon Sep 17 00:00:00 2001
From: Stefano Avallone <stavallo@gmail.com>
Date: Thu, 24 Jul 2025 15:00:36 +0200
Subject: [PATCH] wifi: Make EMLSR link switch test more robust

Wait for one additional TimeStep before checking which link the main
PHY is switching to. We were waiting for a PHY slot to account for
backoff slot alignment, but this is not sufficient when channel access
is delayed by a whole PHY slot because the check is performed before
channel access is granted and the main PHY starts switching.
---
 src/wifi/test/wifi-emlsr-link-switch-test.cc | 24 +++++++++++---------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/src/wifi/test/wifi-emlsr-link-switch-test.cc b/src/wifi/test/wifi-emlsr-link-switch-test.cc
index f0b33865d..297923ca2 100644
--- a/src/wifi/test/wifi-emlsr-link-switch-test.cc
+++ b/src/wifi/test/wifi-emlsr-link-switch-test.cc
@@ -1677,18 +1677,20 @@ EmlsrSwitchMainPhyBackTest::MainPhySwitchInfoCallback(std::size_t index,
             m_staMacs[0]->GetDevice()->GetNode()->AddApplication(
                 GetApplication(UPLINK, 0, 1, 500, 4));
             // channel access can be obtained within a slot due to slot alignment
-            Simulator::Schedule(m_apMac->GetWifiPhy(m_linkIdForTid4)->GetSlot(), [=, this]() {
-                auto advEmlsrMgr =
-                    DynamicCast<AdvancedEmlsrManager>(m_staMacs[0]->GetEmlsrManager());
+            Simulator::Schedule(
+                m_apMac->GetWifiPhy(m_linkIdForTid4)->GetSlot() + TimeStep(1),
+                [=, this]() {
+                    auto advEmlsrMgr =
+                        DynamicCast<AdvancedEmlsrManager>(m_staMacs[0]->GetEmlsrManager());
 
-                NS_TEST_EXPECT_MSG_EQ(advEmlsrMgr->m_mainPhySwitchInfo.disconnected,
-                                      true,
-                                      "Expected the main PHY to be switching");
-                NS_TEST_EXPECT_MSG_EQ(
-                    +advEmlsrMgr->m_mainPhySwitchInfo.to,
-                    +(advEmlsrMgr->m_interruptSwitching ? m_linkIdForTid4 : m_mainPhyId),
-                    "Main PHY is switching to wrong link");
-            });
+                    NS_TEST_EXPECT_MSG_EQ(advEmlsrMgr->m_mainPhySwitchInfo.disconnected,
+                                          true,
+                                          "Expected the main PHY to be switching");
+                    NS_TEST_EXPECT_MSG_EQ(
+                        +advEmlsrMgr->m_mainPhySwitchInfo.to,
+                        +(advEmlsrMgr->m_interruptSwitching ? m_linkIdForTid4 : m_mainPhyId),
+                        "Test index " << +m_testIndex << ": Main PHY is switching to wrong link");
+                });
         });
         InsertEventsForQosTid4();
     };