[nexus] add test 5.1.3 Router Address Reallocation (openthread#12365)

Adds a new Nexus test case for 'Router Address Reallocation – DUT attaches
to new partition' (5.1.3) as specified in the test specification.

Summary of changes:
- Implemented Nexus test 5.1.3:
    - Added test_5_1_3.cpp: Sets up a Leader, Router_1 (DUT), and Router_2
      topology. Uses AllowList to dynamically control connectivity,
      verifying that Router_1 reattaches to a new partition formed by
      Router_2 after the original Leader is removed. Uses direct core
      method calls and avoids magic numbers.
    - Added verify_5_1_3.py: PCAP verification script for test 5.1.3,
      ensuring MLE Parent Requests, Child ID Requests, and Address Solicit
      messages follow the specification.
- Updated build and execution scripts:
    - Modified CMakeLists.txt to build the new 5.1.3 test executable.
    - Updated run_nexus_tests.sh to include 5.1.3 in the default test list.

Author: jwhui

tests/nexus/CMakeLists.txt

@@ -115,6 +115,7 @@ endmacro()
 
 ot_nexus_test(5_1_1)
 ot_nexus_test(5_1_2)
+ot_nexus_test(5_1_3)
 ot_nexus_test(border_agent)
 ot_nexus_test(border_agent_tracker)
 ot_nexus_test(discover_scan)

tests/nexus/run_nexus_tests.sh

@@ -50,6 +50,7 @@ NEXUS_BIN_DIR="${BUILD_DIR}/tests/nexus"
 DEFAULT_TESTS=(
     "5_1_1"
     "5_1_2"
+    "5_1_3"
 )
 
 # Use provided arguments or the default test list

tests/nexus/test_5_1_3.cpp

@@ -0,0 +1,239 @@
+/*
+ *  Copyright (c) 2026, The OpenThread Authors.
+ *  All rights reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions are met:
+ *  1. Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *  3. Neither the name of the copyright holder nor the
+ *     names of its contributors may be used to endorse or promote products
+ *     derived from this software without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *  POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+
+#include "platform/nexus_core.hpp"
+#include "platform/nexus_node.hpp"
+
+namespace ot {
+namespace Nexus {
+
+/**
+ * Time to advance for a node to form a network and become leader, in milliseconds.
+ */
+static constexpr uint32_t kFormNetworkTime = 13 * 1000;
+
+/**
+ * Time to advance for a node to join as a child and upgrade to a router, in milliseconds.
+ */
+static constexpr uint32_t kAttachToRouterTime = 200 * 1000;
+
+/**
+ * Maximum value for Partition ID.
+ */
+static constexpr uint32_t kMaxPartitionId = 0xffffffff;
+
+/**
+ * Network ID Timeout for Router_2, in seconds.
+ */
+static constexpr uint8_t kRouter2NetworkIdTimeout = 100;
+
+/**
+ * Network ID Timeout for Router_1 (DUT), in seconds.
+ */
+static constexpr uint8_t kRouter1NetworkIdTimeout = 120;
+
+/**
+ * Time to wait for Router_2 to time out and become leader, in milliseconds.
+ */
+static constexpr uint32_t kRouter2TimeoutWaitTime = (kRouter2NetworkIdTimeout + 20) * 1000;
+
+/**
+ * Total time to wait for Router_1 (DUT) to time out and reattach, in milliseconds.
+ * This accounts for the 120s timeout plus a small buffer for state transitions.
+ */
+static constexpr uint32_t kRouter1TotalTimeoutWaitTime = (kRouter1NetworkIdTimeout + 20) * 1000;
+
+/**
+ * Incremental time to advance for Router_1 (DUT) reattachment, in milliseconds.
+ */
+static constexpr uint32_t kRouter1TimeoutWaitTime = kRouter1TotalTimeoutWaitTime - kRouter2TimeoutWaitTime;
+
+void Test5_1_3(void)
+{
+    /**
+     * 5.1.3 Router Address Reallocation – DUT attaches to new partition
+     *
+     * 5.1.3.1 Topology
+     * - Set Partition ID on Leader to max value
+     * - Set Router_2 NETWORK_ID_TIMEOUT to 110 seconds (10 seconds faster than default). If the DUT uses a timeout
+     *   faster than default, timing may need to be adjusted.
+     *
+     * 5.1.3.2 Purpose & Description
+     * The purpose of this test case is to verify that after the removal of the Leader from the network, the DUT will
+     * first attempt to reattach to the original partition (P1), and then attach to a new partition (P2).
+     *
+     * Spec Reference                             | V1.1 Section    | V1.3.0 Section
+     * -------------------------------------------|-----------------|-----------------
+     * Router ID Management / Router ID Assignment | 5.9.9 / 5.9.10  | 5.9.9 / 5.9.10
+     */
+
+    Core nexus;
+
+    Node &leader  = nexus.CreateNode();
+    Node &router1 = nexus.CreateNode();
+    Node &router2 = nexus.CreateNode();
+
+    leader.SetName("LEADER");
+    router1.SetName("ROUTER_1");
+    router2.SetName("ROUTER_2");
+
+    nexus.AdvanceTime(0);
+
+    Instance::SetLogLevel(kLogLevelInfo);
+
+    /**
+     * Step 1: Router_2
+     * - Description: Harness configures the NETWORK ID TIMEOUT to be 110 seconds.
+     * - Pass Criteria: N/A
+     */
+    router2.Get<Mle::Mle>().SetNetworkIdTimeout(kRouter2NetworkIdTimeout);
+
+    /**
+     * Step 2: All
+     * - Description: Verify topology is formed correctly
+     * - Pass Criteria: N/A
+     */
+
+    /** Use AllowList feature to restrict the topology. */
+    leader.AllowList(router1);
+    router1.AllowList(leader);
+
+    leader.AllowList(router2);
+    router2.AllowList(leader);
+
+    router1.AllowList(router2);
+    router2.AllowList(router1);
+
+    leader.Get<Mle::Mle>().SetPreferredLeaderPartitionId(kMaxPartitionId);
+    leader.Form();
+    nexus.AdvanceTime(kFormNetworkTime);
+    VerifyOrQuit(leader.Get<Mle::Mle>().IsLeader());
+
+    router1.Join(leader);
+    nexus.AdvanceTime(kAttachToRouterTime);
+    VerifyOrQuit(router1.Get<Mle::Mle>().IsRouter());
+
+    router2.Join(leader);
+    nexus.AdvanceTime(kAttachToRouterTime);
+    VerifyOrQuit(router2.Get<Mle::Mle>().IsRouter());
+
+    /**
+     * Step 3: Leader
+     * - Description: Harness silently powers-off the Leader
+     * - Pass Criteria: N/A
+     */
+    leader.Get<Mle::Mle>().Stop();
+
+    /**
+     * Step 4: Router_2
+     * - Description: Times out after 110 seconds and automatically creates a new partition (P2) with itself as the
+     *   Leader of P2
+     * - Pass Criteria: N/A
+     */
+    nexus.AdvanceTime(kRouter2TimeoutWaitTime);
+    VerifyOrQuit(router2.Get<Mle::Mle>().IsLeader());
+
+    /**
+     * Step 5: Router_1 (DUT)
+     * - Description: Times out after 120 seconds and automatically attempts to reattach to original partition (P1)
+     * - Pass Criteria:
+     *   - The DUT MUST attempt to reattach to its original partition (P1) by sending a MLE Parent Request with an IP
+     *     Hop Limit of 255 to the Link-Local All-Routers multicast address (FF02::2).
+     *   - The following TLVs MUST be present in the MLE Parent Request:
+     *     - Challenge TLV
+     *     - Mode TLV
+     *     - Scan Mask TLV (MUST have E and R flags set)
+     *     - Version TLV
+     *   - The DUT MUST make two separate attempts to reconnect to its original partition (P1) in this manner.
+     */
+    nexus.AdvanceTime(kRouter1TimeoutWaitTime);
+
+    /**
+     * Step 6: Router_1 (DUT)
+     * - Description: Automatically attempts to attach to any other partition
+     * - Pass Criteria:
+     *   - The DUT MUST attempt to attach to any other partition within range by sending a MLE Parent Request.
+     *   - The following TLVs MUST be present in the MLE Parent Request:
+     *     - Challenge TLV
+     *     - Mode TLV
+     *     - Scan Mask TLV
+     *     - Version TLV
+     */
+
+    /**
+     * Step 7: Router_1 (DUT)
+     * - Description: Automatically attaches to Router_2’s partition (P2)
+     * - Pass Criteria:
+     *   - The DUT MUST send a properly formatted Child ID Request to Router_2.
+     *   - The following TLVs MUST be present in the Child ID Request:
+     *     - Link-layer Frame Counter TLV
+     *     - Mode TLV
+     *     - Response TLV
+     *     - Timeout TLV
+     *     - TLV Request TLV
+     *     - Version TLV
+     *     - MLE Frame Counter TLV (optional)
+     *   - The following TLV MUST NOT be present in the Child ID Request:
+     *     - Address Registration TLV
+     */
+
+    /**
+     * Step 8: Router_1 (DUT)
+     * - Description: Automatically sends Address Solicit Request
+     * - Pass Criteria:
+     *   - The DUT MUST send an Address Solicit Request.
+     *   - Ensure the Address Solicit Request is properly formatted:
+     *     - CoAP Request URI: coap://[<leader address>]:MM/a/as
+     *     - CoAP Payload:
+     *       - MAC Extended Address TLV
+     *       - Status TLV
+     *       - RLOC16 TLV (optional)
+     */
+    nexus.AdvanceTime(kAttachToRouterTime);
+    VerifyOrQuit(router1.Get<Mle::Mle>().IsRouter());
+
+    /**
+     * Step 9: Router_2
+     * - Description: Automatically responds with Address Solicit Response Message
+     * - Pass Criteria: N/A
+     */
+
+    nexus.SaveTestInfo("test_5_1_3.json");
+}
+
+} // namespace Nexus
+} // namespace ot
+
+int main(void)
+{
+    ot::Nexus::Test5_1_3();
+    printf("All tests passed\n");
+    return 0;
+}