test: Verify routing preference 255 is inactive

Fixes #784

test/case/ietf_routing/Readme.adoc

@@ -17,3 +17,5 @@ include::ospf_bfd/Readme.adoc[]
 include::route_pref_ospf/Readme.adoc[]
 
 include::route_pref_dhcp/Readme.adoc[]
+
+include::route_pref_255/Readme.adoc[]

test/case/ietf_routing/ietf_routing.yaml

@@ -19,3 +19,6 @@
 
 - name: route_pref_dhcp
   case: route_pref_dhcp/test.py
+
+- name: route_pref_255
+  case: route_pref_255/test.py

test/case/ietf_routing/route_pref_255/Readme.adoc

@@ -0,0 +1,29 @@
+=== Route preference: Static Route Activation and Maximum Distance
+==== Description
+This test configures a device with a static route to a destination with 
+a moderate routing preference (254), verifying that it becomes active. 
+Then, the routing preference is increased to the maximum value (255), 
+which should prevent the route from becoming active.
+
+==== Topology
+ifdef::topdoc[]
+image::../../test/case/ietf_routing/route_pref_255/topology.svg[Route preference: Static Route Activation and Maximum Distance topology]
+endif::topdoc[]
+ifndef::topdoc[]
+ifdef::testgroup[]
+image::route_pref_255/topology.svg[Route preference: Static Route Activation and Maximum Distance topology]
+endif::testgroup[]
+ifndef::testgroup[]
+image::topology.svg[Route preference: Static Route Activation and Maximum Distance topology]
+endif::testgroup[]
+endif::topdoc[]
+==== Test sequence
+. Set up topology and attach to target DUTs
+. Configure targets with active static route
+. Verify that static route with preference 254 is active
+. Update static route preference to 255
+. Verify that high-preference static route (255) does not become active
+
+
+<<<
+

test/case/ietf_routing/route_pref_255/test.py

@@ -0,0 +1,118 @@
+#!/usr/bin/env python3
+"""
+Route preference: Static Route Activation and Maximum Distance
+
+This test configures a device with a static route to a destination with 
+a moderate routing preference (254), verifying that it becomes active. 
+Then, the routing preference is increased to the maximum value (255), 
+which should prevent the route from becoming active.
+"""
+
+import infamy
+import infamy.route as route
+from infamy.util import until, parallel
+
+def configure_interface(name, ip, prefix_length, forwarding=True):
+    return {
+        "name": name,
+        "enabled": True,
+        "ipv4": {
+            "forwarding": forwarding,
+            "address": [{"ip": ip, "prefix-length": prefix_length}]
+        }
+    }
+
+def config_target1_initial(target, data, link):
+    target.put_config_dicts({
+        "ietf-interfaces": {
+            "interfaces": {
+                "interface": [
+                    configure_interface(data, "192.168.10.1", 24),
+                    configure_interface(link, "192.168.50.1", 24)
+                ]
+            }
+        },
+        "ietf-routing": {
+            "routing": {
+                "control-plane-protocols": {
+                    "control-plane-protocol": [
+                        {
+                            "type": "infix-routing:static",
+                            "name": "default",
+                            "static-routes": {
+                                "ipv4": {
+                                    "route": [{
+                                        "destination-prefix": "192.168.20.0/24",
+                                        "next-hop": {"next-hop-address": "192.168.50.2"},
+                                        "route-preference": 254
+                                    }]
+                                }
+                            }
+                        }
+                    ]
+                }
+            }
+        }
+    })
+
+def config_target1_update(target):
+    target.put_config_dicts({
+        "ietf-routing": {
+            "routing": {
+                "control-plane-protocols": {
+                    "control-plane-protocol": [
+                        {
+                            "type": "infix-routing:static",
+                            "name": "default",
+                            "static-routes": {
+                                "ipv4": {
+                                    "route": [{
+                                        "destination-prefix": "192.168.20.0/24",
+                                        "next-hop": {"next-hop-address": "192.168.50.2"},
+                                        "route-preference": 255
+                                    }]
+                                }
+                            }
+                        }
+                    ]
+                }
+            }
+        }
+    })
+
+def config_target2(target, data, link):
+    target.put_config_dicts({
+        "ietf-interfaces": {
+            "interfaces": {
+                "interface": [
+                    configure_interface(data, "192.168.20.2", 24),
+                    configure_interface(link, "192.168.50.2", 24)
+                ]
+            }
+        }
+    })
+
+with infamy.Test() as test:
+    with test.step("Set up topology and attach to target DUTs"):
+        env = infamy.Env()
+        R1 = env.attach("R1", "mgmt")
+        R2 = env.attach("R2", "mgmt")
+
+    with test.step("Configure targets with active static route"):
+        _, R1data = env.ltop.xlate("R1", "data")
+        _, R1link = env.ltop.xlate("R1", "link")
+        _, R2data = env.ltop.xlate("R2", "data")
+        _, R2link = env.ltop.xlate("R2", "link")
+
+        parallel(config_target1_initial(R1, R1data, R1link), config_target2(R2, R2data, R2link))
+
+    with test.step("Verify that static route with preference 254 is active"):
+        until(lambda: route.ipv4_route_exist(R1, "192.168.20.0/24", proto="ietf-routing:static", active_check=True))
+
+    with test.step("Update static route preference to 255"):
+        config_target1_update(R1)
+
+    with test.step("Verify that high-preference static route (255) does not become active"):
+        until(lambda: not route.ipv4_route_exist(R1, "192.168.20.0/24", proto="ietf-routing:static", active_check=True))
+
+    test.succeed()

test/case/ietf_routing/route_pref_255/topology.dot

@@ -0,0 +1,38 @@
+graph "route-preference" {
+	layout="neato";
+	overlap="false";
+	esep="+20";
+	size=10
+
+        node [shape=record, fontname="DejaVu Sans Mono, Book"];
+	edge [color="cornflowerblue", penwidth="2", fontname="DejaVu Serif, Book"];
+
+	PC	
+	[
+		label="PC | { <mgmt1> mgmt1 | <data1> data1 |  <data2> data2 | <mgmt2> mgmt2 }",
+	    	pos="20,58!",
+	    	kind="controller",
+	];
+
+        R1 
+	[
+		label="{ <mgmt> mgmt | <data> data | <link> link } | R1",
+		pos="80,60!",
+		kind="infix",
+	];
+
+	R2 
+	[
+	    	label="{ <link> link | <data> data | <mgmt> mgmt } | R2",
+	    	pos="80,42!",
+	    	kind="infix",
+	];
+
+	PC:mgmt1 -- R1:mgmt [kind=mgmt, color="lightgray"]
+        PC:mgmt2 -- R2:mgmt [kind=mgmt, color="lightgray"]
+
+	PC:data1 -- R1:data  [color="black", headlabel="192.168.10.1/24", taillabel="192.168.10.11/24", fontcolor="black"]
+	PC:data2 -- R2:data  [color="black", headlabel="192.168.20.2/24", taillabel="192.168.20.22/24", fontcolor="black"]
+
+	R1:link -- R2:link  [headlabel="192.168.50.2/24", taillabel="192.168.50.1/24", labeldistance=1, fontcolor="black", color="black"]
+}