test(storage): add out-of-bounds chown coverage for go code and script

plugins/storage/subcommands_test.go

@@ -0,0 +1,17 @@
+package storage
+
+import (
+	"testing"
+
+	. "github.com/onsi/gomega"
+)
+
+func TestResolveChownIDRejectsOutOfBoundsValues(t *testing.T) {
+	RegisterTestingT(t)
+
+	for _, chownFlag := range []string{"-1", "65536", "100000", "231072", "abc", "1.5", ""} {
+		_, err := ResolveChownID(chownFlag)
+		Expect(err).To(HaveOccurred(), "expected %q to be rejected", chownFlag)
+		Expect(err.Error()).To(ContainSubstring("Unsupported chown permissions"))
+	}
+}