policy: Fix capture full state with simple line

For capture like `default-gw: override me with the cache`, nmstate
should store the full state to `default-gw`.

Example file created and will be used for unit tests.

Signed-off-by: Gris Ge <[email protected]>

examples/policy/capture_all/current.yml

@@ -0,0 +1,21 @@
+---
+routes:
+  running:
+    - destination: 0.0.0.0/0
+      next-hop-interface: eth1
+      next-hop-address: 192.0.2.1
+  config:
+    - destination: 0.0.0.0/0
+      next-hop-interface: eth1
+      next-hop-address: 192.0.2.1
+interfaces:
+  - name: eth1
+    type: ethernet
+    state: up
+    mac-address: 1c:c1:0c:32:3b:ff
+    ipv4:
+      enabled: true
+      dhcp: false
+      address:
+        - ip: 192.0.2.251
+          prefix-length: 24

examples/policy/capture_all/expected.yml

@@ -0,0 +1,23 @@
+---
+routes:
+  config:
+    - destination: 0.0.0.0/0
+      next-hop-interface: br1
+      next-hop-address: 192.0.2.1
+interfaces:
+  - name: br1
+    description: Linux bridge with base interface as a port
+    type: linux-bridge
+    state: up
+    ipv4:
+      enabled: true
+      dhcp: false
+      address:
+        - ip: 192.0.2.251
+          prefix-length: 24
+    bridge:
+      options:
+        stp:
+          enabled: false
+      port:
+        - name: eth1

examples/policy/capture_all/policy.yml

@@ -0,0 +1,25 @@
+---
+capture:
+  default-gw: override me with the cache
+  base-iface: >-
+    interfaces.name == capture.default-gw.routes.running.0.next-hop-interface
+  base-iface-routes: >-
+    routes.running.next-hop-interface ==
+    capture.default-gw.routes.running.0.next-hop-interface
+  bridge-routes: >-
+    capture.base-iface-routes | routes.running.next-hop-interface:="br1"
+desiredState:
+  interfaces:
+    - bridge:
+        options:
+          stp:
+            enabled: false
+        port:
+          - name: "{{ capture.base-iface.interfaces.0.name }}"
+      description: Linux bridge with base interface as a port
+      ipv4: "{{ capture.base-iface.interfaces.0.ipv4 }}"
+      name: br1
+      state: up
+      type: linux-bridge
+  routes:
+    config: "{{ capture.bridge-routes.routes.running }}"

rust/src/lib/policy/capture.rs

@@ -192,7 +192,8 @@ impl NetworkCaptureCommand {
                     )
                 });
             } else {
-                return Ok(NetworkState::new());
+                // User just want to store full state to a new name
+                return Ok(input);
             }
         }