tests: add a test for snapctl is-connected --pid

tests/main/snapctl-is-connected-pid/task.yaml

@@ -0,0 +1,37 @@
+summary: Ensure that "snapctl is-connected --pid" works.
+
+prepare: |
+  #shellcheck source=tests/lib/snaps.sh
+  . "$TESTSLIB"/snaps.sh
+  install_local test-snap1
+  install_local test-snap2
+
+execute: |
+  echo "The test-snap1 service is running"
+  systemctl is-active snap.test-snap1.svc.service
+
+  svc_pid=$(systemctl show --property=MainPID snap.test-snap1.svc.service | cut -d = -f 2)
+
+  echo "Plugs and slots are initially disconnected"
+  not test-snap2.snapctl is-connected bar-plug
+  not test-snap2.snapctl is-connected foo-slot
+
+  echo "Disconnected interfaces are not connected to a snap process"
+  not test-snap2.snapctl is-connected --pid "$svc_pid" bar-plug
+  not test-snap2.snapctl is-connected --pid "$svc_pid" foo-slot
+
+  echo "Disconnected interfaces are not connected to non-snap process"
+  not test-snap2.snapctl is-connected --pid 1 bar-plug
+  not test-snap2.snapctl is-connected --pid 1 foo-slot
+
+  echo "Connect interfaces"
+  snap connect test-snap1:foo-plug test-snap2:foo-slot
+  snap connect test-snap2:bar-plug test-snap1:bar-slot
+
+  echo "Connected interfaces report as connected to snap process"
+  test-snap2.snapctl is-connected --pid "$svc_pid" bar-plug
+  test-snap2.snapctl is-connected --pid "$svc_pid" foo-slot
+
+  echo "Interfaces still not connected to non-snap process"
+  not test-snap2.snapctl is-connected --pid 1 bar-plug
+  not test-snap2.snapctl is-connected --pid 1 foo-slot

tests/main/snapctl-is-connected-pid/test-snap1/bin/service.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+
+echo "service running"
+exec sleep infinity

tests/main/snapctl-is-connected-pid/test-snap1/meta/snap.yaml

@@ -0,0 +1,21 @@
+name: test-snap1
+version: 1
+summary: First test snap
+
+plugs:
+  foo-plug:
+    interface: content
+    content: foo
+    target: $SNAP_COMMON/foo
+
+slots:
+  bar-slot:
+    interface: content
+    content: bar
+    read:
+      - $SNAP
+
+apps:
+  svc:
+    command: bin/service.sh
+    daemon: simple

tests/main/snapctl-is-connected-pid/test-snap2/bin/run-snapctl.sh

@@ -0,0 +1,2 @@
+#!/bin/sh
+exec snapctl "$@"

tests/main/snapctl-is-connected-pid/test-snap2/meta/snap.yaml

@@ -0,0 +1,20 @@
+name: test-snap2
+version: 1
+summary: Second test snap
+
+plugs:
+  bar-plug:
+    interface: content
+    content: bar
+    target: $SNAP_COMMON/bar
+
+slots:
+  foo-slot:
+    interface: content
+    content: foo
+    read:
+      - $SNAP
+
+apps:
+  snapctl:
+    command: bin/run-snapctl.sh