From 9f7b0d8f0c876d8a1d5da98397bf64c9ab964097 Mon Sep 17 00:00:00 2001
From: Maximilian Bosch <maximilian@mbosch.me>
Date: Fri, 24 Jun 2022 09:58:40 +0200
Subject: [PATCH] nixos/systemd-networkd-vrf: check routing tables via `ip
 --json`

The original implementation did a simple string-comparison against the
output of `ip route`. This is problematic because

* if the details in the string-output change, the test breaks. This is
  less likely with JSON because the relevant values (i.e. destination,
  interface etc) aren't supposed to be changed.
* this is causing issues with formatters[1][2].

[1] #161703
[2] #154818
---
 nixos/tests/systemd-networkd-vrf.nix | 50 ++++++++++++++++++----------
 1 file changed, 32 insertions(+), 18 deletions(-)

diff --git a/nixos/tests/systemd-networkd-vrf.nix b/nixos/tests/systemd-networkd-vrf.nix
index 3839a49375d..3c18f788e92 100644
--- a/nixos/tests/systemd-networkd-vrf.nix
+++ b/nixos/tests/systemd-networkd-vrf.nix
@@ -138,18 +138,18 @@ in {
   };
 
   testScript = ''
-    def compare_tables(expected, actual):
-        assert (
-            expected == actual
-        ), """
-        Routing tables don't match!
-        Expected:
-          {}
-        Actual:
-          {}
-        """.format(
-            expected, actual
-        )
+    import json
+
+    def compare(raw_json, to_compare):
+        data = json.loads(raw_json)
+        assert len(raw_json) >= len(to_compare)
+        for i, row in enumerate(to_compare):
+            actual = data[i]
+            assert len(row.keys()) > 0
+            for key, value in row.items():
+                assert value == actual[key], f"""
+                  In entry {i}, value {key}: got: {actual[key]}, expected {value}
+                """
 
 
     start_all()
@@ -178,14 +178,28 @@ in {
     # Check that networkd properly configures the main routing table
     # and the routing tables for the VRF.
     with subtest("check vrf routing tables"):
-        compare_tables(
-            client_ipv4_table, client.succeed("ip -4 route list | head -n2").strip()
+        compare(
+            client.succeed("ip --json -4 route list"),
+            [
+                {"dst": "192.168.1.2", "dev": "vrf1", "metric": 100},
+                {"dst": "192.168.2.3", "dev": "vrf2", "metric": 100}
+            ]
         )
-        compare_tables(
-            vrf1_table, client.succeed("ip -4 route list table 23 | head -n4").strip()
+        compare(
+            client.succeed("ip --json -4 route list table 23"),
+            [
+                {"dst": "192.168.1.0/24", "dev": "eth1", "prefsrc": "192.168.1.1"},
+                {"type": "local", "dst": "192.168.1.1", "dev": "eth1", "prefsrc": "192.168.1.1"},
+                {"type": "broadcast", "dev": "eth1", "prefsrc": "192.168.1.1", "dst": "192.168.1.255"}
+            ]
         )
-        compare_tables(
-            vrf2_table, client.succeed("ip -4 route list table 42 | head -n4").strip()
+        compare(
+            client.succeed("ip --json -4 route list table 42"),
+            [
+                {"dst": "192.168.2.0/24", "dev": "eth2", "prefsrc": "192.168.2.1"},
+                {"type": "local", "dst": "192.168.2.1", "dev": "eth2", "prefsrc": "192.168.2.1"},
+                {"type": "broadcast", "dev": "eth2", "prefsrc": "192.168.2.1", "dst": "192.168.2.255"}
+            ]
         )
 
     # Ensure that other nodes are reachable via ICMP through the VRF.