selftests: drv-net: validate the environment

Throw a slightly more helpful exception when env variables
are partially populated. Prior to this change we'd get
a dictionary key exception somewhere later on.
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20240425222341.309778-4-kuba@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/drivers/net/lib/py/env.py

@@ -88,6 +88,7 @@ class NetDrvEpEnv:
         self._ns_peer = None
 
         if "NETIF" in self.env:
+            self._check_env()
             self.dev = ip("link show dev " + self.env['NETIF'], json=True)[0]
 
             self.v4 = self.env.get("LOCAL_V4")
@@ -143,6 +144,30 @@ class NetDrvEpEnv:
         ip(f"-6 addr add dev {self._ns_peer.nsims[0].ifname} {self.nsim_v6_pfx}2/64 nodad", ns=self._netns)
         ip(f"   link set dev {self._ns_peer.nsims[0].ifname} up", ns=self._netns)
 
+    def _check_env(self):
+        vars_needed = [
+            ["LOCAL_V4", "LOCAL_V6"],
+            ["REMOTE_V4", "REMOTE_V6"],
+            ["REMOTE_TYPE"],
+            ["REMOTE_ARGS"]
+        ]
+        missing = []
+
+        for choice in vars_needed:
+            for entry in choice:
+                if entry in self.env:
+                    break
+            else:
+                missing.append(choice)
+        # Make sure v4 / v6 configs are symmetric
+        if ("LOCAL_V6" in self.env) != ("REMOTE_V6" in self.env):
+            missing.append(["LOCAL_V6", "REMOTE_V6"])
+        if ("LOCAL_V4" in self.env) != ("REMOTE_V4" in self.env):
+            missing.append(["LOCAL_V4", "REMOTE_V4"])
+        if missing:
+            raise Exception("Invalid environment, missing configuration:", missing,
+                            "Please see tools/testing/selftests/drivers/net/README.rst")
+
     def __enter__(self):
         return self