Add fuzz tests for v1alpha5 conversion

Unlike the v1alpha6 and v1alpha7 tests, these only test if the
conversion causes a panic. It found 1 panic, which is also fixed here.

api/v1alpha5/conversion.go

@@ -456,6 +456,10 @@ func Convert_v1alpha5_Instance_To_v1beta1_BastionStatus(in *Instance, out *infra
 	out.State = infrav1.InstanceState(in.State)
 	out.IP = in.IP
 	out.FloatingIP = in.FloatingIP
+
+	if out.Resolved == nil {
+		out.Resolved = &infrav1.ResolvedMachineSpec{}
+	}
 	out.Resolved.ServerGroupID = in.ServerGroupID
 	return nil
 }
@@ -468,7 +472,9 @@ func Convert_v1beta1_BastionStatus_To_v1alpha5_Instance(in *infrav1.BastionStatu
 	out.State = InstanceState(in.State)
 	out.IP = in.IP
 	out.FloatingIP = in.FloatingIP
-	out.ServerGroupID = in.Resolved.ServerGroupID
+	if in.Resolved != nil {
+		out.ServerGroupID = in.Resolved.ServerGroupID
+	}
 	return nil
 }
 

api/v1alpha5/conversion_test.go

@@ -17,14 +17,20 @@ limitations under the License.
 package v1alpha5
 
 import (
+	"runtime/debug"
 	"testing"
 
 	"github.com/onsi/gomega"
+	"github.com/onsi/gomega/format"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	runtime "k8s.io/apimachinery/pkg/runtime"
+	runtimeserializer "k8s.io/apimachinery/pkg/runtime/serializer"
+	"k8s.io/client-go/kubernetes/scheme"
+	utilconversion "sigs.k8s.io/cluster-api/util/conversion"
 	ctrlconversion "sigs.k8s.io/controller-runtime/pkg/conversion"
 
 	infrav1 "sigs.k8s.io/cluster-api-provider-openstack/api/v1beta1"
+	testhelpers "sigs.k8s.io/cluster-api-provider-openstack/test/helpers"
 )
 
 func TestConvertFrom(t *testing.T) {
@@ -165,3 +171,69 @@ func TestConvert_v1alpha5_OpenStackClusterSpec_To_v1beta1_OpenStackClusterSpec(t
 		})
 	}
 }
+
+type convertiblePointer[T any] interface {
+	ctrlconversion.Convertible
+	*T
+}
+
+type hubPointer[T any] interface {
+	ctrlconversion.Hub
+	*T
+}
+
+func test_ObjectConvert[SP convertiblePointer[S], HP hubPointer[H], S, H any](tb testing.TB) {
+	tb.Helper()
+
+	fuzzerFuncs := func(_ runtimeserializer.CodecFactory) []interface{} {
+		return testhelpers.InfraV1FuzzerFuncs()
+	}
+	f := utilconversion.GetFuzzer(scheme.Scheme, fuzzerFuncs)
+	g := gomega.NewWithT(tb)
+
+	for i := 0; i < 10000; i++ {
+		var hub HP = new(H)
+		f.Fuzz(hub)
+		var spoke SP = new(S)
+
+		func() {
+			defer func() {
+				if r := recover(); r != nil {
+					tb.Errorf("PANIC! Down-converting:\n%s\n%s", format.Object(hub, 1), debug.Stack())
+					tb.FailNow()
+				}
+			}()
+			g.Expect(spoke.ConvertFrom(hub)).To(gomega.Succeed())
+		}()
+
+		spoke = new(S)
+		f.Fuzz(spoke)
+		hub = new(H)
+
+		func() {
+			defer func() {
+				if r := recover(); r != nil {
+					tb.Errorf("PANIC! Up-converting:\n%s\n%s", format.Object(spoke, 1), debug.Stack())
+					tb.FailNow()
+				}
+			}()
+			g.Expect(spoke.ConvertTo(hub)).To(gomega.Succeed())
+		}()
+	}
+}
+
+func Test_OpenStackClusterConvert(t *testing.T) {
+	test_ObjectConvert[*OpenStackCluster, *infrav1.OpenStackCluster](t)
+}
+
+func Test_OpenStackClusterTemplate(t *testing.T) {
+	test_ObjectConvert[*OpenStackClusterTemplate, *infrav1.OpenStackClusterTemplate](t)
+}
+
+func Test_OpenStackMachineConvert(t *testing.T) {
+	test_ObjectConvert[*OpenStackMachine, *infrav1.OpenStackMachine](t)
+}
+
+func Test_OpenStackMachineTemplateConvert(t *testing.T) {
+	test_ObjectConvert[*OpenStackMachineTemplate, *infrav1.OpenStackMachineTemplate](t)
+}