test(agentcompat): add process supervision harness

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

integration/agentcompat/internal/process/fd_path_test.go

@@ -0,0 +1,30 @@
+//go:build linux
+
+package process
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestProcessHasOpenPathTogglesWithDescriptorLifecycle(t *testing.T) {
+	// Given
+	path := filepath.Join(t.TempDir(), "dashboard.sqlite-journal")
+	require.NoError(t, os.WriteFile(path, []byte("journal"), 0o600))
+	file, err := os.Open(path)
+	require.NoError(t, err)
+
+	// When
+	held, err := ProcessHasOpenPath(os.Getpid(), path)
+	require.NoError(t, err)
+	require.NoError(t, file.Close())
+	released, err := ProcessHasOpenPath(os.Getpid(), path)
+
+	// Then
+	require.NoError(t, err)
+	require.True(t, held)
+	require.False(t, released)
+}